From: Matt Reimer Date: Thu, 8 Jun 2006 21:46:48 +0000 (+0100) Subject: [ARM] 3546/1: PATCH: subtle lost interrupts bug on i.MX X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e2f04e18941dbd3826901540a0be03f1728f8822;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git [ARM] 3546/1: PATCH: subtle lost interrupts bug on i.MX Patch from Matt Reimer There is a subtle bug in the GPIO interrupt status register handling in arch/arm/mach-imx/irq.c:imx_gpio_ack_irq(). The documentation states that a 1 should be written to the relevant bit to acknowledge a GPIO interrupt, but that is not what the code does. The problem is that the |= writes back 1s for all the *other* interrupts represented in the register, so interrupts could get lost. For example, if interrupts are pending for GPIO B10 and B12, ISR_B would have the value 0x00001400. Then when the interrupt code handles GPIO B10, it eventually calls imx_gpio_ack_irq(IRQ_GPIOB(10)), which effectively does this: ISR_B |= 1 << 10; with the result that (0x00001400 | 0x00000400) is written, clearing the interrupt status bits for *both* GPIO B10 and B12. The fix is to write 1s only for the interrupts we want to clear. The same problem seems to be occurring in the DMA code; this patch does not address those issues. Acked-by: Sascha Hauer Signed-off-by: Matt Reimer Signed-off-by: Russell King --- diff --git a/arch/arm/mach-imx/irq.c b/arch/arm/mach-imx/irq.c index eeb8a6d4a399..a5de5f1da9f2 100644 --- a/arch/arm/mach-imx/irq.c +++ b/arch/arm/mach-imx/irq.c @@ -127,7 +127,7 @@ static void imx_gpio_ack_irq(unsigned int irq) { DEBUG_IRQ("%s: irq %d\n", __FUNCTION__, irq); - ISR(IRQ_TO_REG(irq)) |= 1 << ((irq - IRQ_GPIOA(0)) % 32); + ISR(IRQ_TO_REG(irq)) = 1 << ((irq - IRQ_GPIOA(0)) % 32); } static void