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fca8892ae5
We uncovered a limitation of this core WRT to the Link Layer Compliance Suite's TD7.06. On that test, host will start a GetDescriptor(DEVICE) standard request, but it will do so only on the SETUP phase, meaning there will *NOT* be any DATA or STATUS phases. The idea of the test is to verify robustness of the IP WRT framing errors, so the test will send a sequence of different SETUP_DPs each with a different framing error and the Suite expects us to be able to receive all SETUP_DPs with no timeouts. This core, has the ability to tell us which phase the host is expecting before we start it. Whenever we receive a TP or DP when no transfers are cached on the internal IP's caches, the IP will generate a XferNotReady event with status informing us (in case of physical ep0/ep1) if it's related to DATA or STATUS phases - SETUP phase is expected to be prestarted. Because we're always waiting for XferNotReady events for DATA and STATUS phases, we will never be able to know that the Host wants to start another SETUP phase instead, which will render us "not compliant" with TD7.06. In order to "fix" the problem we must not rely on XferNotReady events for the DATA phase and try to always pre-start DATA transfers on physical endpoints 0 and 1. If host goes back to SETUP phase from DATA phase we will receive a XferComplete for that phase with TRB's status set to SETUP_PENDING, which is only useful for printing a debugging log as the core expects us to still go through to the STATUS phase, initiate a CONTROL_STATUS TRB just so it completes right away and, only then, we go back to the pending SETUP phase. SNPS has decided to modify the programming model of the core so that on-demand DATA phases will not be supported anymore. Note that this limitation does not affect 2-stage transfers, meaning that if TD7.06 would start a 2-stage transfer instead of a 3-stage transfer, we would receive a "fake" XferNotReady(STATUS) which would complete right after being initiated with SETUP_PENDING status. Other endpoints are also not affected, so we can still use on-demand transfers on Bulk/Isoc/Interrupt endpoints. Signed-off-by: Felipe Balbi <balbi@ti.com> |
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| gadget | ||
| host | ||
| image | ||
| misc | ||
| mon | ||
| musb | ||
| otg | ||
| phy | ||
| renesas_usbhs | ||
| serial | ||
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| wusbcore | ||
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| Makefile | ||
| README | ||
| usb-common.c | ||
| usb-skeleton.c | ||
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("khubd").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.