linux_dsm_epyc7002/drivers/tty
Philipp Puschmann 76c38d30fe serial: imx: adapt rx buffer and dma periods
Using only 4 DMA periods for UART RX is very few if we have a high
frequency of small transfers - like in our case using Bluetooth with
many small packets via UART - causing many dma transfers but in each
only filling a fraction of a single buffer. Such a case may lead to
the situation that DMA RX transfer is triggered but no free buffer is
available. When this happens dma channel ist stopped - with the patch
"dmaengine: imx-sdma: fix dma freezes" temporarily only - with the
possible consequences that:
with disabled hw flow control:
  If enough data is incoming on UART port the RX FIFO runs over and
  characters will be lost. What then happens depends on upper layer.

with enabled hw flow control:
  If enough data is incoming on UART port the RX FIFO reaches a level
  where CTS is deasserted and remote device sending the data stops.
  If it fails to stop timely the i.MX' RX FIFO may run over and data
  get lost. Otherwise it's internal TX buffer may getting filled to
  a point where it runs over and data is again lost. It depends on
  the remote device how this case is handled and if it is recoverable.

Obviously we want to avoid having no free buffers available. So we
decrease the size of the buffers and increase their number and the
total buffer size.

Signed-off-by: Philipp Puschmann <philipp.puschmann@emlix.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://lore.kernel.org/r/20190923135916.1212-1-philipp.puschmann@emlix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-04 14:46:13 +02:00
..
hvc tty: hvcs: Fix odd use of strlcpy 2019-09-04 12:43:44 +02:00
ipwireless tty: add SPDX identifiers to Kconfig and Makefiles 2019-04-04 18:48:43 +02:00
serdev tty: add SPDX identifiers to Kconfig and Makefiles 2019-04-04 18:48:43 +02:00
serial serial: imx: adapt rx buffer and dma periods 2019-10-04 14:46:13 +02:00
vt vt: Grab console_lock around con_is_bound in show_bind 2019-07-25 13:47:35 +02:00
amiserial.c kill TIOCSERGSTRUCT 2018-10-13 00:50:53 -04:00
cyclades.c cyclades: switch to ->[sg]et_serial() 2018-10-13 00:50:30 -04:00
ehv_bytechan.c tty: Convert to using %pOFn instead of device_node.name 2018-09-18 16:07:25 +02:00
goldfish.c headers: separate linux/mod_devicetable.h from linux/platform_device.h 2018-07-07 17:52:26 +02:00
isicom.c tty/isicom: remove redundant assignment to variable word_count 2019-09-04 12:43:44 +02:00
Kconfig docs: serial: move it to the driver-api 2019-07-15 11:03:03 -03:00
Makefile tty: Add NULL TTY driver 2019-04-16 15:21:34 +02:00
mips_ejtag_fdc.c
moxa.c moxa: switch to ->[sg]et_serial() 2018-10-13 00:50:32 -04:00
moxa.h
mxser.c mxser: switch to ->[sg]et_serial() 2018-10-13 00:50:32 -04:00
mxser.h
n_gsm.c tty: n_gsm: avoid recursive locking with async port hangup 2019-09-04 12:43:56 +02:00
n_hdlc.c tty/n_hdlc: mark expected switch fall-through 2019-02-14 10:49:19 +01:00
n_null.c
n_r3964.c tty: Don't block on IO when ldisc change is pending 2018-12-05 12:16:33 +01:00
n_tracerouter.c
n_tracesink.c
n_tracesink.h
n_tty.c n_tty: check for negative and zero space return from tty_write_room 2019-04-16 15:21:33 +02:00
nozomi.c tty: nozomi: Use dev_get_drvdata 2019-09-04 12:43:44 +02:00
pty.c Revert "tty: pty: Fix race condition between release_one_tty and pty_write" 2019-03-29 15:47:40 +01:00
rocket_int.h
rocket.c TTY/Serial patches for 5.2-rc1 2019-05-08 10:07:28 -07:00
rocket.h tty: rocket: Remove RCPK_GET_STRUCT ioctl 2019-04-25 11:58:56 +02:00
synclink_gt.c synclink_gt(): fix compat_ioctl() 2018-10-13 00:50:52 -04:00
synclink.c tty/synclink: remove ISA support 2019-02-12 08:51:33 +01:00
synclinkmp.c synclink: reduce pointless checks in ->ioctl() 2018-10-13 00:50:43 -04:00
sysrq.c panic: avoid the extra noise dmesg 2019-05-14 19:52:51 -07:00
tty_audit.c audit: join tty records to their syscall 2019-02-07 21:33:54 -05:00
tty_baudrate.c termios, tty/tty_baudrate.c: fix buffer overrun 2018-11-08 03:36:45 -08:00
tty_buffer.c tty: increase the default flip buffer limit to 2*640K 2019-01-30 12:03:58 +01:00
tty_io.c drivers: Introduce device lookup variants by device type 2019-07-30 13:07:42 +02:00
tty_ioctl.c move compat handling of tty ioctls to tty_compat_ioctl() 2018-09-14 11:12:17 -04:00
tty_jobctrl.c tty: fix read of tty->pgrp outside of ctrl_lock 2019-03-28 01:28:23 +09:00
tty_ldisc.c proc/sysctl: add shared variables for range check 2019-07-18 17:08:07 -07:00
tty_ldsem.c tty/ldsem, locking/rwsem: Add missing ACQUIRE to read_failed sleep loop 2019-07-25 15:39:24 +02:00
tty_mutex.c
tty_port.c Revert "tty: fix NULL pointer issue when tty_port ops is not set" 2019-04-16 15:21:34 +02:00
ttynull.c tty: Add NULL TTY driver 2019-04-16 15:21:34 +02:00
vcc.c tty: fix up a few remaining files without SPDX identifiers 2019-04-04 18:48:43 +02:00