On Mon, 1 Feb 2021 13:24:00 +0000 Steven Price steven.price@arm.com wrote:
On 01/02/2021 12:59, Boris Brezillon wrote:
On Mon, 1 Feb 2021 12:13:49 +0000 Steven Price steven.price@arm.com 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@collabora.com
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.
I think I'll just queue everything to misc-next and let the stable maintainers backport the fixes (no one complained about this issue so far).
Thanks,
Steve
Regardless:
Reviewed-by: Steven Price steven.price@arm.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;- mmu_write(pfdev, MMU_INT_MASK, ~0); return IRQ_HANDLED; };