[PATCH 2/3] aspeed-video: clear spurious interrupt bits unconditionally
joel at jms.id.au
Tue Dec 22 15:47:37 AEDT 2020
On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev at bewilderbeest.net> wrote:
> Instead of testing and conditionally clearing them one by one, we can
> instead just unconditionally clear them all at once.
> Signed-off-by: Zev Weiss <zev at bewilderbeest.net>
I had a poke at the assembly and it looks like GCC is clearing the
bits unconditionally anyway, so removing the tests provides no change.
Combining them is a good further optimization.
Reviewed-by: Joel Stanley <joel at jms.id.au>
A question unrelated to this patch: Do you know why the driver doesn't
clear the status bits in the interrupt handler? I would expect it to
write the value of sts back to the register to ack the pending
> drivers/media/platform/aspeed-video.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
> diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c
> index eb02043532e3..218aae3be809 100644
> --- a/drivers/media/platform/aspeed-video.c
> +++ b/drivers/media/platform/aspeed-video.c
> @@ -558,6 +558,14 @@ static void aspeed_video_irq_res_change(struct aspeed_video *video, ulong delay)
> schedule_delayed_work(&video->res_work, delay);
> + * Interrupts that we don't use but have to explicitly ignore because the
> + * hardware asserts them even when they're disabled in the VE_INTERRUPT_CTRL
> + * register.
> + */
> +#define VE_SPURIOUS_IRQS \
> + (VE_INTERRUPT_CAPTURE_COMPLETE | VE_INTERRUPT_FRAME_COMPLETE)
> static irqreturn_t aspeed_video_irq(int irq, void *arg)
> struct aspeed_video *video = arg;
> @@ -630,15 +638,8 @@ static irqreturn_t aspeed_video_irq(int irq, void *arg)
> - /*
> - * CAPTURE_COMPLETE and FRAME_COMPLETE interrupts come even when these
> - * are disabled in the VE_INTERRUPT_CTRL register so clear them to
> - * prevent unnecessary interrupt calls.
> - */
> - if (sts & VE_INTERRUPT_CAPTURE_COMPLETE)
> - sts &= ~VE_INTERRUPT_CAPTURE_COMPLETE;
> - if (sts & VE_INTERRUPT_FRAME_COMPLETE)
> - sts &= ~VE_INTERRUPT_FRAME_COMPLETE;
> + /* Squash known bogus interrupts */
> + sts &= ~VE_SPURIOUS_IRQS;
> if (sts)
> dev_err_ratelimited(video->dev, "unexpected interrupt asserted:"
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