On 01/02/2021 12:59, Boris Brezillon wrote:
On Mon, 1 Feb 2021 12:13:49 +0000
Steven Price <steven.price@xxxxxxx> wrote:
On 01/02/2021 08:21, Boris Brezillon 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@xxxxxxxxxxxxx>
Looks fine to me, but I'm interested to know if you actually saw a
performance improvement. Back-to-back MMU faults should (hopefully) be
fairly uncommon.
I actually didn't check the perf improvement or the actual number of
back-to-back MMU faults, but
dEQP-GLES31.functional.draw_indirect.compute_interop.large.drawelements_combined_grid_1000x1000_drawcount_5000
seemed to generate a few of those, so I thought it'd be good to
optimize that case given how trivial it is.
Fair enough! I was just a little concerned that Panfrost was somehow
provoking enough interrupts that this was a measurable performance
improvement.
I assume you'll push these to drm-misc-next (/fixes) as appropriate.
Thanks,
Steve
Regardless:
Reviewed-by: Steven Price <steven.price@xxxxxxx>
---
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;
+
mmu_write(pfdev, MMU_INT_MASK, ~0);
return IRQ_HANDLED;
};
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