Two cpufreq notifiers CPUFREQ_RESUMECHANGE and CPUFREQ_SUSPENDCHANGE have
not been used for some time, so remove them to clean up code a bit.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Extend the driver to with support for SCIx device tree bindings. A
minimal set of features is supported, additional properties can be added
later should the need to describe more device features arise.
Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The fields are not used anymore by board files, remove them.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The field isn't set by any board, remote it.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Computing the baud rate register value requires knowledge of the
hardware sampling rate. This information is currently encoded in a baud
rate calculation algorithm ID passed through platform data. However, it
can be derived from the port type directly in most cases.
Compute the sampling rate internally in the driver if the baud rate
calculation algorithm ID isn't specified, and allow platforms to
override the sampling rate through platform data in special cases (this
is only required for SCIFA ports on sh7723 and sh7724, the reason needs
to be investigated).
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The overrun bit index is a property of the hardware. It's currently
computed based on a different and unrelated hardware property, the baud
rate calculation algorithm. Compute it using hardware identification
information only.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The driver requests at initialization time GPIOs passed through platform
data. No platform makes use of this feature, remove it.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
None of the fields is ever set by board code, and both of them are set
in the driver at probe time. Move them out of struct plat_sci_port to
struct sci_port.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Memory and IRQ resources are currently passed to the driver through
platform data. Support passing them through the standard platform
resources mechanism instead. This deprecates platform data resources.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The IRQ number can't be modified by the user as the port is fixed.
There's no need to check the new IRQ number as it will be ignored by the
core.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The base address, IRQ and baud rate generator parent clock rate can't be
changed by userspace. Mark the port as fixed.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The driver checks if the interrupt number is greater than nr_irqs and
returns an error in that case. The same check is already performed by
the caller, remove it.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Rewrite the baud rate register value calculations in easier to read
forms. The computed value isn't modified.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Turn clk_enable() and clk_disable() calls into clk_prepare_enable() and
clk_disable_unprepare() to get ready for the migration to the common
clock framework.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Magnus Damm <damm@opensource.se>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
The break timer accesses hardware registers and thus requires the port
to be enabled. It currently ensures this by enabling the port at the
beginning of the timer handler, and disabling it at the end. However,
the enable/disable operations call the runtime PM sync functions, which
are not allowed in atomic context. The current situation is thus broken.
This change relies on non-atomic code to enable/disable the port. The
break timer will only be started from the IRQ handler, which already
runs with the port enabled. We just need to ensure that the port won't
be disabled with the timer running, and that's easily done by just
cancelling the timer in the port disable function.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Magnus Damm <damm@opensource.se>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Use the %zu and %pad printk specifiers to print size_t and dma_addr_t
variables, and cast pointers to uintptr_t instead of unsigned int where
applicable. This fixes warnings on platforms where pointers and/or
dma_addr_t have a different size than int.
Cc: linux-serial@vger.kernel.org
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Use the wrapper function for retrieving the platform data instead of
accessing dev->platform_data directly
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use the wrapper function for retrieving the platform data instead of
accessing dev->platform_data directly.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This change addresses two warnings that are flagged by gcc relating to
potential access to the ssr and cks variables while they are uninitialised.
I have addressed this by initialising the values to
the defaults present in sci_baud_calc_hscif().
It is my analysis that cks is always initialised if used
but that without this change ssr may be accessed while uninitialised.
The code altered by this patch was introduced by commit
f303b364b4 ("serial: sh-sci: HSCIF support").
Reported-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Adds support for "High Speed Serial Communications Interface with FIFO",
essentially a SCIF with 128-byte FIFOs and more accurate baud rate
generator.
Signed-off-by: Ulrich Hecht <ulrich.hecht@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.
Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.
IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.
Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.
tty_insert_flip_char is the next one to proceed. This one is used all
over the code, so the patch is huge.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty pointer in
many call sites. Only tty_port will be needed and hence no more
tty_port_tty_get calls in those paths.
Here we start with tty_buffer_request_room.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CONFIG_HOTPLUG is going away as an option so __devinit is no longer
needed.
Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Cc: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Lucas Tavares <lucaskt@linux.vnet.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Tony Prisk <linux@prisktech.co.nz>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the previous commit, console write function (serial_console_write)
is changed to disable SCI interrupts while printing console strings.
This introduces possible race cases in the serial startup / shutdown
functions on SMP systems.
This patch fixes the sh-sci in the same way as commit 9ec1882df2
(tty: serial: imx: console write routing is unsafe on SMP, from
Xinyu Chen <xinyu.chen@freescale.com>, 2012-08-27) did.
There could be several consumers of the console,
* the kernel printk
* the init process using /dev/kmsg to call printk to show log
* shell, which opens /dev/console and writes with sys_write()
The shell goes into the normal UART open() and write() system calls,
while the other two go into the console operations. The open() call
invokes serial startup function (sci_startup), which will write to
the SCSCR register (to enable or disable SCI interrupts) without any
locking. This will conflict with the console serial function.
Add spinlock protections in sci_startup() and sci_shutdown() properly.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Symptom:
When entering the suspend with Android logcat running, printk() call
gets stuck and never returns. The issue can be observed at printk()s
on nonboot CPUs when going to offline with their interrupts disabled,
and never seen at boot CPU (core0 in our case).
Details:
serial_console_write() lacks of appropriate spinlock handling.
In SMP systems, as long as sci_transmit_chars() is being processed
at one CPU core, serial_console_write() can stuck at the other CPU
core(s), when it tries to access to the same serial port _without_
a proper locking. serial_console_write() waits for the transmit FIFO
getting empty, while sci_transmit_chars() writes data to the FIFO.
In general, peripheral interrupts are routed to boot CPU (core0) by
Linux ARM standard affinity settings. SCI(F) interrupts are handled
by core0, so sci_transmit_chars() is processed on core0 as well.
When logcat is running, it writes enormous log data to the kernel at
every moment, forever. So core0 can repeatedly continue to process
sci_transmit_chars() in its interrupt handler, which eventually makes
the other CPU core(s) stuck at serial_console_write().
Looking at serial/8250.c, this is a known console write lockup issue
with SMP kernels. Fix the sh-sci driver in the same way 8250.c does.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
About FIFO count, there are two variants of SCIFs which show
a) TX count in upper, RX count in lower byte of FDR register
b) TX count in TFDR register, RX count in RFDR register
Common SCIFB regmap in current source code is defined as "a".
At least 7372 and 73a0 HW manual say their SICFB are "b".
This patch alters the definition to "b", considering the current
one has come from a mistake. The reason is as follows.
The flag SCIFB sh-sci driver means it has 256 byte FIFO.
The count is from 0(empty) to 256(full), that makes 9-bit.
Because FDR is 16-bit register, it can not hold two 9-bits.
That's why, SCIFB can not be "a".
Signed-off-by: Takashi Yoshii <takashi.yoshii.zj@renesas.com>
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Current mask 0xff to SCTFDR/RFDR damages SCIFB, because the
registers on SCIFB have 9-bit data (0 to 256).
This patch changes the mask according to port->fifosize.
Though I'm not sure if the mask is really needed (I don't know if
there are variants which have non-zero upper bits), it is safer.
Signed-off-by: Takashi Yoshii <takashi.yoshii.zj@renesas.com>
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Support prescaler 1/16 and 1/64, in addition to current 1 and 1/4.
Supporting below 2400bps was dropped long time ago in mainline.
Since then, setting lower rate has been resulting in erroneous
register value, without indicating any errors through API.
This patch adds more prescaler to support lower rates again.
This still doesn't check range, but we won't hit the case because
even 50bps at 48MHz clock is now supported.
Signed-off-by: Takashi Yoshii <takashi.yoshii.zj@renesas.com>
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit 1ba7622094 (serial: sh-sci: console Runtime PM support,
from Magnus Damm <damm@opensource.se>, 2011-08-03), tried to support
console runtime PM, but unfortunately it didn't work for us for some
reason. We did not investigated further at that time, instead would
like to propose a different approach.
In Linux tty/serial world, to get console PM work properly, a serial
client driver does not have to maintain .runtime_suspend()/..resume()
calls itself, but can leave console power power management handling to
the serial core driver.
This patch moves the sh-sci driver in that direction.
Notes:
* There is room to optimize console runtime PM more aggressively by
maintaining additional local runtime PM calls, but as a first step
having .pm() operation would suffice.
* We still have a couple of direct calls to sci_port_enable/..disable
left in the driver. We have to live with them, because they're out
of serial core's help.
Signed-off-by: Teppei Kamijou <teppei.kamijou.yb@renesas.com>
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This partially reverts commit 1ba7622094 (serial: sh-sci: console
Runtime PM support, from Magnus Damm <damm@opensource.se>, 2011-08-03).
The generic 'serial_core' can take care of console PM maintenance,
so all (or at least the first thing) we have to do to get console PM
work properly, is to implement uart_ops ->pm() operation in the sh-sci
serial client driver.
This patch partially reverts the commit above, but leaving sci_reset()
change in place, because sci_reset() is already part of another commit
(73c3d53f38 serial: sh-sci: Avoid FIFO clear for MCE toggle.).
A revised version of console PM support follows next.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 5a50a01bf0 (sh-sci / PM: Use power.irq_safe, from
Rafael J. Wysocki <rjw@sisk.pl>, 2011-08-24).
In order to get console PM work properly, we should implement uart_ops
->pm() operation, rather than sprinkle band-ading runtime PM calls in
the driver.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 048be431e4 (sh-sci / PM: Avoid deadlocking runtime
PM, from Rafael J. Wysocki <rjw@sisk.pl>, 2012-03-09).
In order to get console PM work properly, we should implement uart_ops
->pm() operation, rather than sprinkle band-ading runtime PM calls in
the driver.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It was already pointed out how to fix these cases before the offending
patches were merged, but unsurprisingly, that didn't happen. As this
change is entirely superfluous to begin with, simply shut things up by
casting everything away.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
A recent commit:
commit d6fa5a4e7a
Author: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
serial: sh-sci: prepare for conversion to the shdma base library
is not sufficient to update the sh-sci driver to the new shdma driver
layout. This caused compilation breakage, when CONFIG_SERIAL_SH_SCI_DMA
is enabled. This patch trivially fixes the problem by updating the DMA
descriptor manipulation code.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Pull slave-dmaengine update from Vinod Koul:
"This time we have a new dmaengine driver from the tegra folks. Also
we have Guennadi's cleanup of sh drivers which incudes a library for
sh drivers. And the usual odd fixes in bunch of drivers and some nice
cleanup of dw_dmac from Andy."
Fix up conflicts in drivers/mmc/host/sh_mmcif.c
* 'next' of git://git.infradead.org/users/vkoul/slave-dma: (46 commits)
dmaengine: Cleanup logging messages
mmc: sh_mmcif: switch to the new DMA channel allocation and configuration
dma: sh: provide a migration path for slave drivers to stop using .private
dma: sh: use an integer slave ID to improve API compatibility
dmaengine: shdma: prepare to stop using struct dma_chan::private
sh: remove unused DMA device pointer from SIU platform data
ASoC: siu: don't use DMA device for channel filtering
dmaengine: shdma: (cosmetic) simplify a static function
dmaengine: at_hdmac: add a few const qualifiers
dw_dmac: use 'u32' for LLI structure members, not dma_addr_t
dw_dmac: mark dwc_dump_lli inline
dma: mxs-dma: Export missing symbols from mxs-dma.c
dma: shdma: convert to the shdma base library
ASoC: fsi: prepare for conversion to the shdma base library
usb: renesas_usbhs: prepare for conversion to the shdma base library
ASoC: siu: prepare for conversion to the shdma base library
serial: sh-sci: prepare for conversion to the shdma base library
mmc: sh_mobile_sdhi: prepare for conversion to the shdma base library
mmc: sh_mmcif: remove unneeded struct sh_mmcif_dma, prepare to shdma conversion
dma: shdma: prepare for conversion to the shdma base library
...
The driver supports a maximum number of ports configurable at compile
time. Make sure the probe() method fails when registering a port that
exceeds the maximum instead of returning success without registering the
port.
This fixes a crash at system suspend time, when the driver tried to
suspend a non-registered port using the UART core.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
When probing fails, the driver must not try to cleanup resources that
have not been initialized. Fix this.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
In doing the evt2irq() + muxed vector conversion for various port types
it became apparent that some of the legacy port types will presently
error out due to the irq requesting logic attempting to acquire the
non-existent BRI IRQ. This adds some sanity checks to the request/free
path to ensure that non-existence of a source in itself is not an error.
This should restore functionality for legacy PORT_SCI ports.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This updates the earlier break_ctl support regardless of regtype so long
as the requisite SCSPTR exists. This is the same approach used by
sci_init_pins() for providing a generic solution now that we're able to
detect register capabilities on a per-port basis.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
SCIF modules which have SCSPTR can output the break signal. Now that we
have a way of determining port features/capabilities, add trivial break
control via SCSPTR support. Tested on sh7757lcr.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Follows the 8250 change for pretty much the same rationale.
See commit "serial: use serial_port_in/out vs serial_in/out in 8250".
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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Merge tag 'sh-for-linus' of git://github.com/pmundt/linux-sh
Pull SuperH updates from Paul Mundt.
* tag 'sh-for-linus' of git://github.com/pmundt/linux-sh: (25 commits)
sh: Support I/O space swapping where needed.
sh: use set_current_blocked() and block_sigmask()
sh: no need to reset handler if SA_ONESHOT
sh: intc: Fix up section mismatch for intc_ack_data
sh: select ARCH_DISCARD_MEMBLOCK.
sh: Consolidate duplicate _32/_64 unistd definitions.
sh: ecovec: switch SDHI controllers to card polling
sh: Avoid exporting unimplemented syscalls.
sh: add platform_device for RSPI in setup-sh7757
SH: pci-sh7780: enable big-endian operation.
serial: sh-sci: fix a race of DMA submit_tx on transfer
sh: dma: Collect up CHCR of SH7763, SH7764, SH7780 and SH7785
sh: dma: Collect up CHCR of SH7723 and SH7730
sh/next: Fix build fail by asm/system.h in asm/bitops.h
arch/sh/drivers/dma/{dma-g2,dmabrg}.c: ensure arguments to request_irq and free_irq are compatible
sh: cpufreq: Wire up scaling_available_freqs support.
sh: cpufreq: notify about rate rounding fallback.
sh: cpufreq: Support CPU clock frequency table.
sh: cpufreq: struct device lookup from CPU topology.
sh: cpufreq: percpu struct clk accounting.
...
Pull slave-dmaengine update from Vinod Koul:
"This includes the cookie cleanup by Russell, the addition of context
parameter for dmaengine APIs, more arm dmaengine driver cleanup by
moving code to dmaengine, this time for imx by Javier and pl330 by
Boojin along with the usual driver fixes."
Fix up some fairly trivial conflicts with various other cleanups.
* 'next' of git://git.infradead.org/users/vkoul/slave-dma: (67 commits)
dmaengine: imx: fix the build failure on x86_64
dmaengine: i.MX: Fix merge of cookie branch.
dmaengine: i.MX: Add support for interleaved transfers.
dmaengine: imx-dma: use 'dev_dbg' and 'dev_warn' for messages.
dmaengine: imx-dma: remove 'imx_dmav1_baseaddr' and 'dma_clk'.
dmaengine: imx-dma: remove unused arg of imxdma_sg_next.
dmaengine: imx-dma: remove internal structure.
dmaengine: imx-dma: remove 'resbytes' field of 'internal' structure.
dmaengine: imx-dma: remove 'in_use' field of 'internal' structure.
dmaengine: imx-dma: remove sg member from internal structure.
dmaengine: imx-dma: remove 'imxdma_setup_sg_hw' function.
dmaengine: imx-dma: remove 'imxdma_config_channel_hw' function.
dmaengine: imx-dma: remove 'imxdma_setup_mem2mem_hw' function.
dmaengine: imx-dma: remove dma_mode member of internal structure.
dmaengine: imx-dma: remove data member from internal structure.
dmaengine: imx-dma: merge old dma-v1.c with imx-dma.c
dmaengine: at_hdmac: add slave config operation
dmaengine: add context parameter to prep_slave_sg and prep_dma_cyclic
dmaengine/dma_slave: introduce inline wrappers
dma: imx-sdma: Treat firmware messages as warnings instead of erros
...
When DMA is enabled, sh-sci transfer begins with
uart_start()
sci_start_tx()
if (cookie_tx < 0) schedule_work()
Then, starts DMA when wq scheduled, -- (A)
process_one_work()
work_fn_rx()
cookie_tx = desc->submit_tx()
And finishes when DMA transfer ends, -- (B)
sci_dma_tx_complete()
async_tx_ack()
cookie_tx = -EINVAL
(possible another schedule_work())
This A to B sequence is not reentrant, since controlling variables
(for example, cookie_tx above) are not queues nor lists. So, they
must be invoked as A B A B..., otherwise results in kernel crash.
To ensure the sequence, sci_start_tx() seems to test if cookie_tx < 0
(represents "not used") to call schedule_work().
But cookie_tx will not be set (to a cookie, also means "used") until
in the middle of work queue scheduled function work_fn_tx().
This gap between the test and set allows the breakage of the sequence
under the very frequently call of uart_start().
Another gap between async_tx_ack() and another schedule_work() results
in the same issue, too.
This patch introduces a new condition "cookie_tx == 0" just to mark
it is "busy" and assign it within spin-locked region to fill the gaps.
Signed-off-by: Takashi Yoshii <takashi.yoshii.zj@renesas.com>
Reviewed-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: stable@vger.kernel.org
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
