Re: [PATCH v2 3/3] drm/panfrost: Stay in the threaded MMU IRQ handler until we've handled all IRQs

On 05/02/2021 11:17, 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.

v2:

• Rework the loop to avoid a goto

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

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

---

drivers/gpu/drm/panfrost/panfrost_mmu.c | 26 +++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index 21e552d1ac71..0581186ebfb3 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -578,22 +578,20 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data) { struct panfrost_device *pfdev = data; u32 status = mmu_read(pfdev, MMU_INT_RAWSTAT);

• int i, ret;

• int ret;

• for (i = 0; status; i++) {

• u32 mask = BIT(i) | BIT(i + 16);
  

• while (status) {

• u32 as = ffs(status | (status >> 16)) - 1;
  

• u32 mask = BIT(as) | BIT(as + 16);
  

  u64 addr; u32 fault_status; u32 exception_type; u32 access_type; u32 source_id;

• if (!(status & mask))
  

• 	continue;
  

• fault_status = mmu_read(pfdev, AS_FAULTSTATUS(i));
  

• addr = mmu_read(pfdev, AS_FAULTADDRESS_LO(i));
  

• addr |= (u64)mmu_read(pfdev, AS_FAULTADDRESS_HI(i)) << 32;
  

• fault_status = mmu_read(pfdev, AS_FAULTSTATUS(as));
  

• addr = mmu_read(pfdev, AS_FAULTADDRESS_LO(as));
  

• addr |= (u64)mmu_read(pfdev, AS_FAULTADDRESS_HI(as)) << 32;
  
  

  /* decode the fault status */ exception_type = fault_status & 0xFF;

@@ -604,8 +602,8 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data)

/* Page fault only */
ret = -1;

• if ((status & mask) == BIT(i) && (exception_type & 0xF8) == 0xC0)
  

• 	ret = panfrost_mmu_map_fault_addr(pfdev, i, addr);
  

• if ((status & mask) == BIT(as) && (exception_type & 0xF8) == 0xC0)
  

• 	ret = panfrost_mmu_map_fault_addr(pfdev, as, addr);
  
  

  if (ret) /* terminal fault, print info about the fault */

@@ -617,7 +615,7 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data) "exception type 0x%X: %s\n" "access type 0x%X: %s\n" "source id 0x%X\n",

• 		i, addr,
  

• 		as, addr,
  	"TODO",
  	fault_status,
  	(fault_status & (1 << 10) ? "DECODER FAULT" : "SLAVE FAULT"),
  

@@ -626,6 +624,10 @@ static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data) source_id);

status &= ~mask;

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

• if (!status)
  

• 	status = mmu_read(pfdev, MMU_INT_RAWSTAT);
  

  }

  mmu_write(pfdev, MMU_INT_MASK, ~0);