On 01/02/2021 08:21, Boris Brezillon wrote:

When a fault is handled it will unblock the GPU which will continue executing its shader and might fault almost immediately on a different page. If we clear interrupts after handling the fault we might miss new faults, so clear them before.

Cc: stable@vger.kernel.org Fixes: 187d2929206e ("drm/panfrost: Add support for GPU heap allocations") Signed-off-by: Boris Brezillon boris.brezillon@collabora.com

Good catch (although this oddly rings a bell - so perhaps it was me you discussed it with before)

Reviewed-by: Steven Price steven.price@arm.com

---

drivers/gpu/drm/panfrost/panfrost_mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index 7c1b3481b785..904d63450862 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -593,6 +593,8 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data) access_type = (fault_status >> 8) & 0x3; source_id = (fault_status >> 16);

• mmu_write(pfdev, MMU_INT_CLEAR, mask);
  

• /* Page fault only */ ret = -1; if ((status & mask) == BIT(i) && (exception_type & 0xF8) == 0xC0)

@@ -616,8 +618,6 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data) access_type, access_type_name(pfdev, fault_status), source_id);

• mmu_write(pfdev, MMU_INT_CLEAR, mask);
  

• status &= ~mask; }