Re: [PATCH 3/3] drm/panfrost: Stay in the threaded MMU IRQ handler until we've handled all IRQs

On Mon, Feb 1, 2021 at 2:21 AM Boris Brezillon boris.brezillon@collabora.com wrote:

Doing a hw-irq -> threaded-irq round-trip is counter-productive, stay in the threaded irq handler as long as we can.

Signed-off-by: Boris Brezillon boris.brezillon@collabora.com

drivers/gpu/drm/panfrost/panfrost_mmu.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index 21e552d1ac71..65bc20628c4e 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -580,6 +580,8 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data) u32 status = mmu_read(pfdev, MMU_INT_RAWSTAT); int i, ret;

+again:

•   for (i = 0; status; i++) {
            u32 mask = BIT(i) | BIT(i + 16);
            u64 addr;
  

@@ -628,6 +630,11 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data) status &= ~mask; }

•   /* If we received new MMU interrupts, process them before returning. */
  

•   status = mmu_read(pfdev, MMU_INT_RAWSTAT);
  

•   if (status)
  

•           goto again;
  

Can't we avoid the goto? Change the for loop like this:

i = 0; while (status = mmu_read(pfdev, MMU_INT_RAWSTAT)) { ...

i++; if (i == 16) i = 0; }

    mmu_write(pfdev, MMU_INT_MASK, ~0);
    return IRQ_HANDLED;

};

2.26.2