linux/drivers/usb
Sebastian Andrzej Siewior a655f481d8 usb: musb: musb_cppi41: handle pre-mature TX complete interrupt
The TX-complete interrupt of the CPPI41 on AM335x fires too early.
Adding a loop and counting how long it takes until the
MUSB_TXCSR_TXPKTRDY bit is cleared I see
FS:
|musb-hdrc musb-hdrc.0.auto: configure ep1/80 packet_sz=64, mode=0, dma_addr=0xadc54002, len=1514 is_tx=1
|cppi41_dma_callback() 74 loops
|musb-hdrc musb-hdrc.0.auto: configure ep1/80 packet_sz=64, mode=0, dma_addr=0xadcd8802, len=1514 is_tx=1
|cppi41_dma_callback() 66 loops
|musb-hdrc musb-hdrc.0.auto: configure ep1/80 packet_sz=64, mode=0, dma_addr=0xadcd8002, len=1514 is_tx=1
|cppi41_dma_callback() 136 loops
|musb-hdrc musb-hdrc.0.auto: configure ep1/80 packet_sz=64, mode=0, dma_addr=0xadf55802, len=1514 is_tx=1
|cppi41_dma_callback() 136 loops

avg: 110 - 150us

HS:
|musb-hdrc musb-hdrc.0.auto: configure ep1/80 packet_sz=512, mode=0, dma_addr=0xaca6f002, len=1514 is_tx=1
|cppi41_dma_callback() 0 loops
|musb-hdrc musb-hdrc.0.auto: configure ep1/80 packet_sz=512, mode=0, dma_addr=0xadd6f802, len=1514 is_tx=1
|cppi41_dma_callback() 2 loops
|musb-hdrc musb-hdrc.0.auto: configure ep1/80 packet_sz=512, mode=0, dma_addr=0xadd6f002, len=1514 is_tx=1
|cppi41_dma_callback() 13 loops

avg: 2us

for the same test case. One loop means a udelay(1). The delay seems to
depend on the packet size. On HS the bit is always cleared for small
packet sizes while on FS it is never the case, it mostly around 110us.
This testing has been performed with g_ether (musb as device) and using BULK
transfers.

INTR transfers are way more fun: during init the gadget sends a INT
packet to the host and cppi41 says "transfer done" shortly after. The
MUSB_TXCSR_TXPKTRDY bit is set even seconds later. The reason is that the host
did not try to receive it, it does so after the interface (on host side) has
been configured. Until this happens, that packet remains in musb's FIFO.

To fix this, two things are done:
- No DMA transfers for INT based endpoints. These transfer are usually
  very small and rare so it is likely better to skip the DMA engine and
  stuff the four bytes directly into the FIFO
- on HS we poll up to 25us and hope that bit goes away. If not we setup
  a hrtimer to poll for it. The 140us delay is a rule of thumb. In FS
  the command
  | ping 10.10.10.10 -c1 -s65130
  creates about 44 1514bytes transfers. About 19 of them need a second
  timer to complete.

Reported-by: Bin Liu <b-liu@ti.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
2013-11-25 10:54:14 -06:00
..
atm usbatm: Fix dynamic_debug / ratelimited atm_dbg and atm_rldbg macros 2013-10-29 16:50:52 -07:00
c67x00 tree-wide: use reinit_completion instead of INIT_COMPLETION 2013-11-15 09:32:21 +09:00
chipidea Merge branch 'for-linus-dma-masks' of git://git.linaro.org/people/rmk/linux-arm 2013-11-14 07:55:21 +09:00
class usb: cdc-wdm: ignore speed change notifications 2013-10-29 17:02:41 -07:00
core More ACPI and power management updates for 3.13-rc1 2013-11-20 13:25:04 -08:00
dwc3 Merge branch 'for-linus-dma-masks' of git://git.linaro.org/people/rmk/linux-arm 2013-11-14 07:55:21 +09:00
early USB: ehci-dbgp: drop dead code. 2013-09-26 16:25:21 -07:00
gadget usb: gadget: fix pxa25x compilation problems 2013-11-25 10:25:58 -06:00
host Merge branch 'for-linus-dma-masks' of git://git.linaro.org/people/rmk/linux-arm 2013-11-14 07:55:21 +09:00
image USB: regroup all depends on USB within an if USB block 2013-04-09 16:49:07 -07:00
misc usb: usbtest: support container id descriptor test 2013-10-30 10:15:41 -07:00
mon USB: regroup all depends on USB within an if USB block 2013-04-09 16:49:07 -07:00
musb usb: musb: musb_cppi41: handle pre-mature TX complete interrupt 2013-11-25 10:54:14 -06:00
phy usb: phy: generic: fix a compiler warning 2013-11-25 10:25:59 -06:00
renesas_usbhs Remove GENERIC_HARDIRQ config option 2013-09-13 15:09:52 +02:00
serial tree-wide: use reinit_completion instead of INIT_COMPLETION 2013-11-15 09:32:21 +09:00
storage usb-storage: add quirk for mandatory READ_CAPACITY_16 2013-10-16 13:32:04 -07:00
wusbcore usb: wusbcore: change WA_SEGS_MAX to a legal value 2013-10-29 16:44:49 -07:00
Kconfig usb: Move definition of USB_EHCI_BIG_ENDIAN_MMIO et al. out side of the ifs. 2013-08-12 12:18:38 -07:00
Makefile usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
README
usb-common.c usb: common: introduce of_usb_get_maximum_speed() 2013-07-29 13:56:46 +03:00
usb-skeleton.c USB: usb-skeleton.c: add retry for nonblocking read 2013-07-25 12:01:13 -07:00

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.