From 762253741942d8ddbaca1c1ee62d7ed57544332b Mon Sep 17 00:00:00 2001 From: Harro Haan Date: Mon, 1 Mar 2010 17:54:55 +0100 Subject: 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 Signed-off-by: Harro Haan Acked-by: Remy Bohmer Acked-by: Andrew Victor Signed-off-by: Russell King --- drivers/usb/gadget/at91_udc.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'drivers') 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; -- cgit v1.2.3