From c6c352371c1ce486a62f4eb92e545b05cfcef76b Mon Sep 17 00:00:00 2001 From: Harro Haan Date: Mon, 1 Mar 2010 17:38:37 +0100 Subject: [PATCH] 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 Acked-by: Harro Haan Tested-by: Remy Bohmer Acked-by: Andrew Victor Cc: David Brownell Signed-off-by: Russell King --- drivers/usb/gadget/at91_udc.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c index 12ac9cd32a07..df1bae9b048e 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; } -- 2.39.5