diff options
| author | Harro Haan <hrhaan@gmail.com> | 2010-03-01 17:54:55 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2010-05-05 10:15:05 +0200 |
| commit | 762253741942d8ddbaca1c1ee62d7ed57544332b (patch) | |
| tree | 752b1aa44843cafbbdf953e3d72ab46a88e032cc /drivers/usb/gadget/at91_udc.c | |
| parent | ARM: 6092/1: atmel_serial: support for RS485 communications (diff) | |
| download | linux-762253741942d8ddbaca1c1ee62d7ed57544332b.tar.xz linux-762253741942d8ddbaca1c1ee62d7ed57544332b.zip | |
ARM: 5966/1: at91_udc HW glitch
Add some delay to avoid reading CSR TXCOUNT too early after
updating it.
For more info about this HW glitch see:
http://lists.arm.linux.org.uk/lurker/message/20090325.150843.f515c02f.en.html
http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20100129/10ba0f8b/attachment.el
http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20100203/09cdb3b4/attachment.el
http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20100203/08b5b249/attachment.el
First applied: "Fix soft lockup in at91 udc driver"
http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=5965
Signed-off-by: Anti Sullin <anti.sullin@artecdesign.ee>
Signed-off-by: Harro Haan <hrhaan@gmail.com>
Acked-by: Remy Bohmer <linux@bohmer.net>
Acked-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'drivers/usb/gadget/at91_udc.c')
| -rw-r--r-- | drivers/usb/gadget/at91_udc.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c index 12ac9cd32a07..b3bd22ef82ba 100644 --- a/drivers/usb/gadget/at91_udc.c +++ b/drivers/usb/gadget/at91_udc.c @@ -366,6 +366,13 @@ rescan: if (is_done) done(ep, req, 0); else if (ep->is_pingpong) { + /* + * One dummy read to delay the code because of a HW glitch: + * CSR returns bad RXCOUNT when read too soon after updating + * RX_DATA_BK flags. + */ + csr = __raw_readl(creg); + bufferspace -= count; buf += count; goto rescan; |