06bdfcdb13
At chipidea revision 2.40a, there is a below errata: 9000531823 B2-Medium Adding a dTD to a Primed Endpoint May Not Get Recognized Title: Adding a dTD to a Primed Endpoint May Not Get Recognized Impacted Configuration: All device mode configurations. Description: There is an issue with the add dTD tripwire semaphore (ATDTW bit in USBCMD register) that can cause the controller to ignore a dTD that is added to a primed endpoint. When this happens, the software can read the tripwire bit and the status bit at '1' even though the endpoint is unprimed. After executing a dTD, the device controller endpoint state machine executes a final read of the dTD terminate bit to check if the application added a dTD to the linked list at the last moment. This read is done in the finpkt_read_latest_next_td (44) state. After the read is performed, if the terminate bit is still set, the state machine moves to unprime the endpoint. The decision to unprime the endpoint is done in the checkqh_decision (59) state, based on the value of the terminate bit. Before reaching the checkqh_decision state, the state machine traverses the writeqhtd_status (57), writeqh_status (56), and release_prime_mask (42) states. As shown in the waveform, the ep_addtd_tripwire_clr signal is not set to clear the tripwire bit in these states. Workaround: The software must implement a periodic poll cycle, and check for each dTD pending on execution (Active = 1), if the enpoint is primed. It can do this by reading the corresponding bits in the ENDPTPRIME and ENDPTSTAT registers. If these bits are read at 0, the software needs to re-prime the endpoint by writing 1 to the corresponding bit in the ENDPTPRIME register. This can be done for every microframe, every frame or with a larger interval, depending on the urgency of transfer execution for the application. Tested-by: Stefan Agner <stefan@agner.ch> Signed-off-by: Peter Chen <peter.chen@freescale.com> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| gadget | ||
| host | ||
| image | ||
| isp1760 | ||
| misc | ||
| mon | ||
| musb | ||
| phy | ||
| renesas_usbhs | ||
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| storage | ||
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| README | ||
| 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 ("hub_wq").
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.