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authorHarro Haan <hrhaan@gmail.com>2010-03-01 17:38:37 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-03-29 17:36:04 +0100
commitc6c352371c1ce486a62f4eb92e545b05cfcef76b (patch)
tree23720c8ff4d431c809d670759bf10f43f78f60ff /drivers/usb
parentfd522a8dec11a08b5fdd23982193808e268be19e (diff)
ARM: 5965/1: Fix soft lockup in at91 udc driver
Fix a potential soft lockup in the AT91 UDC driver by ensuring that the UDC clock is enabled inside the interrupt handler. If the UDC clock is not enabled then the UDC registers cannot be written to and the interrupt cannot be cleared or masked. Note that this patch (and other parts of the existing AT91 UDC driver) is potentially racy for preempt-rt kernels, but is okay for mainline. For more info see: http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20100203/09cdb3b4/attachment.el http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20100203/8443a1e4/attachment.el Signed-off-by: Ryan Mallon <ryan@bluewatersys.com> Acked-by: Harro Haan <hrhaan@gmail.com> Tested-by: Remy Bohmer <linux@bohmer.net> Acked-by: Andrew Victor <avictor.za@gmail.com> Cc: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/gadget/at91_udc.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c
index 12ac9cd32a0..df1bae9b048 100644
--- a/drivers/usb/gadget/at91_udc.c
+++ b/drivers/usb/gadget/at91_udc.c
@@ -1370,6 +1370,12 @@ static irqreturn_t at91_udc_irq (int irq, void *_udc)
{
struct at91_udc *udc = _udc;
u32 rescans = 5;
+ int disable_clock = 0;
+
+ if (!udc->clocked) {
+ clk_on(udc);
+ disable_clock = 1;
+ }
while (rescans--) {
u32 status;
@@ -1458,6 +1464,9 @@ static irqreturn_t at91_udc_irq (int irq, void *_udc)
}
}
+ if (disable_clock)
+ clk_off(udc);
+
return IRQ_HANDLED;
}