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authorHarro Haan <hrhaan@gmail.com>2010-03-01 17:54:55 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-05-05 09:15:05 +0100
commit762253741942d8ddbaca1c1ee62d7ed57544332b (patch)
tree752b1aa44843cafbbdf953e3d72ab46a88e032cc /drivers/usb/gadget
parente8faff7330a3501eafc9bfe5f4f15af444be29f5 (diff)
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')
-rw-r--r--drivers/usb/gadget/at91_udc.c7
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;