[PATCH v3 0/5] drm/panthor: Misc fixes

[PATCH v3 0/5] drm/panthor: Misc fixes

[Boris Brezillon]

Hello,

This is a collection of fixes for bugs found while working on adding
JM support to panthor. Those are not particularly tied to JM support
and are worth having regardless.

Note that the last two don't have Fixes tag because they fix issues
we can't really hit with the current implementation (no fault
handling, and no shared irq line).

Changelog available in each patch if you're interested.

Regards,

Boris

Boris Brezillon (5):
  drm/panthor: Fix GPU_COHERENCY_ACE[_LITE] definitions
  drm/panthor: Call panthor_gpu_coherency_init() after PM resume()
  drm/panthor: Update panthor_mmu::irq::mask when needed
  drm/panthor: Let IRQ handlers clear the interrupts themselves
  drm/panthor: Don't update MMU_INT_MASK in panthor_mmu_irq_handler()

 drivers/gpu/drm/panthor/panthor_device.c | 8 ++++----
 drivers/gpu/drm/panthor/panthor_device.h | 2 --
 drivers/gpu/drm/panthor/panthor_fw.c     | 2 ++
 drivers/gpu/drm/panthor/panthor_gpu.c    | 2 ++
 drivers/gpu/drm/panthor/panthor_mmu.c    | 9 ++++++++-
 drivers/gpu/drm/panthor/panthor_regs.h   | 4 ++--
 6 files changed, 18 insertions(+), 9 deletions(-)

-- 
2.49.0

[PATCH v3 1/5] drm/panthor: Fix GPU_COHERENCY_ACE[_LITE] definitions

[Boris Brezillon]

GPU_COHERENCY_ACE and GPU_COHERENCY_ACE_LITE definitions have been
swapped.

Changes in v2:
- New patch

Changes in v3:
- Add Steve's R-b

Reported-by: Liviu Dudau <liviu.dudau@arm.com>
Fixes: 546b366600ef ("drm/panthor: Add GPU register definitions")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
---
 drivers/gpu/drm/panthor/panthor_regs.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_regs.h b/drivers/gpu/drm/panthor/panthor_regs.h
index b7b3b3add166..a7a323dc5cf9 100644
--- a/drivers/gpu/drm/panthor/panthor_regs.h
+++ b/drivers/gpu/drm/panthor/panthor_regs.h
@@ -133,8 +133,8 @@
 #define GPU_COHERENCY_PROT_BIT(name)			BIT(GPU_COHERENCY_  ## name)
 
 #define GPU_COHERENCY_PROTOCOL				0x304
-#define   GPU_COHERENCY_ACE				0
-#define   GPU_COHERENCY_ACE_LITE			1
+#define   GPU_COHERENCY_ACE_LITE			0
+#define   GPU_COHERENCY_ACE				1
 #define   GPU_COHERENCY_NONE				31
 
 #define MCU_CONTROL					0x700
-- 
2.49.0

Re: [PATCH v3 1/5] drm/panthor: Fix GPU_COHERENCY_ACE[_LITE] definitions

[Liviu Dudau]

On Fri, Apr 04, 2025 at 10:09:29AM +0200, Boris Brezillon wrote:
> GPU_COHERENCY_ACE and GPU_COHERENCY_ACE_LITE definitions have been
> swapped.
> 
> Changes in v2:
> - New patch
> 
> Changes in v3:
> - Add Steve's R-b
> 
> Reported-by: Liviu Dudau <liviu.dudau@arm.com>
> Fixes: 546b366600ef ("drm/panthor: Add GPU register definitions")
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> Reviewed-by: Steven Price <steven.price@arm.com>

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Best regards,
Liviu

> ---
>  drivers/gpu/drm/panthor/panthor_regs.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_regs.h b/drivers/gpu/drm/panthor/panthor_regs.h
> index b7b3b3add166..a7a323dc5cf9 100644
> --- a/drivers/gpu/drm/panthor/panthor_regs.h
> +++ b/drivers/gpu/drm/panthor/panthor_regs.h
> @@ -133,8 +133,8 @@
>  #define GPU_COHERENCY_PROT_BIT(name)			BIT(GPU_COHERENCY_  ## name)
>  
>  #define GPU_COHERENCY_PROTOCOL				0x304
> -#define   GPU_COHERENCY_ACE				0
> -#define   GPU_COHERENCY_ACE_LITE			1
> +#define   GPU_COHERENCY_ACE_LITE			0
> +#define   GPU_COHERENCY_ACE				1
>  #define   GPU_COHERENCY_NONE				31
>  
>  #define MCU_CONTROL					0x700
> -- 
> 2.49.0
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

[PATCH v3 2/5] drm/panthor: Call panthor_gpu_coherency_init() after PM resume()

[Boris Brezillon]

When the device is coherent, panthor_gpu_coherency_init() will read
GPU_COHERENCY_FEATURES to make sure the GPU supports the ACE-Lite
coherency protocol, which will fail if the clocks/power-domains are
not enabled when the read is done. Move the
panthor_gpu_coherency_init() call after the device has been resumed
to prevent that.

Changes in v2:
- Add Liviu's R-b

Changes in v3:
- Add Steve's R-b

Fixes: dd7db8d911a1 ("drm/panthor: Explicitly set the coherency mode")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
---
 drivers/gpu/drm/panthor/panthor_device.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index a9da1d1eeb70..c73c1608d6e6 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -171,10 +171,6 @@ int panthor_device_init(struct panthor_device *ptdev)
 	struct page *p;
 	int ret;
 
-	ret = panthor_gpu_coherency_init(ptdev);
-	if (ret)
-		return ret;
-
 	init_completion(&ptdev->unplug.done);
 	ret = drmm_mutex_init(&ptdev->base, &ptdev->unplug.lock);
 	if (ret)
@@ -247,6 +243,10 @@ int panthor_device_init(struct panthor_device *ptdev)
 	if (ret)
 		goto err_rpm_put;
 
+	ret = panthor_gpu_coherency_init(ptdev);
+	if (ret)
+		return ret;
+
 	ret = panthor_mmu_init(ptdev);
 	if (ret)
 		goto err_unplug_gpu;
-- 
2.49.0

[PATCH v3 3/5] drm/panthor: Update panthor_mmu::irq::mask when needed

[Boris Brezillon]

When we clear the faulty bits in the AS mask, we also need to update
the panthor_mmu::irq::mask field otherwise our IRQ handler won't get
called again until the GPU is reset.

Changes in v2:
- Add Liviu's R-b

Changes in v3:
- Add Steve's R-b

Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 12a02e28f50f..7cca97d298ea 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -781,6 +781,7 @@ int panthor_vm_active(struct panthor_vm *vm)
 	if (ptdev->mmu->as.faulty_mask & panthor_mmu_as_fault_mask(ptdev, as)) {
 		gpu_write(ptdev, MMU_INT_CLEAR, panthor_mmu_as_fault_mask(ptdev, as));
 		ptdev->mmu->as.faulty_mask &= ~panthor_mmu_as_fault_mask(ptdev, as);
+		ptdev->mmu->irq.mask |= panthor_mmu_as_fault_mask(ptdev, as);
 		gpu_write(ptdev, MMU_INT_MASK, ~ptdev->mmu->as.faulty_mask);
 	}
 
-- 
2.49.0

[PATCH v3 4/5] drm/panthor: Let IRQ handlers clear the interrupts themselves

[Boris Brezillon]

MMU handler needs to be in control of the job interrupt clears because
clearing the interrupt also unblocks the writer/reader that triggered
the fault, and we don't want it to be unblocked until we've had a chance
to process the IRQ.

Since clearing the clearing is just one line, let's make it explicit
instead of doing it in the generic code path.

Note that this commit changes the existing behavior in that the MMU
COMPLETED irqs are no longer cleared, which is fine because they are
masked, so we're not risking an interrupt flood.

Changes in v3:
- Mention the fact we no longer clear MMU COMPLETED irqs
- Add Liviu's R-b

Changes in v2:
- Move the MMU_INT_CLEAR around

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
---
 drivers/gpu/drm/panthor/panthor_device.h | 2 --
 drivers/gpu/drm/panthor/panthor_fw.c     | 2 ++
 drivers/gpu/drm/panthor/panthor_gpu.c    | 2 ++
 drivers/gpu/drm/panthor/panthor_mmu.c    | 7 +++++++
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index da6574021664..4c27b6d85f46 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -383,8 +383,6 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
 		if (!status)									\
 			break;									\
 												\
-		gpu_write(ptdev, __reg_prefix ## _INT_CLEAR, status);				\
-												\
 		__handler(ptdev, status);							\
 		ret = IRQ_HANDLED;								\
 	}											\
diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index 0f52766a3120..446bb377b953 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -1008,6 +1008,8 @@ static void panthor_fw_init_global_iface(struct panthor_device *ptdev)
 
 static void panthor_job_irq_handler(struct panthor_device *ptdev, u32 status)
 {
+	gpu_write(ptdev, JOB_INT_CLEAR, status);
+
 	if (!ptdev->fw->booted && (status & JOB_INT_GLOBAL_IF))
 		ptdev->fw->booted = true;
 
diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
index 671049020afa..32d678a0114e 100644
--- a/drivers/gpu/drm/panthor/panthor_gpu.c
+++ b/drivers/gpu/drm/panthor/panthor_gpu.c
@@ -150,6 +150,8 @@ static void panthor_gpu_init_info(struct panthor_device *ptdev)
 
 static void panthor_gpu_irq_handler(struct panthor_device *ptdev, u32 status)
 {
+	gpu_write(ptdev, GPU_INT_CLEAR, status);
+
 	if (status & GPU_IRQ_FAULT) {
 		u32 fault_status = gpu_read(ptdev, GPU_FAULT_STATUS);
 		u64 address = ((u64)gpu_read(ptdev, GPU_FAULT_ADDR_HI) << 32) |
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 7cca97d298ea..0ba76982d45b 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -1710,6 +1710,13 @@ static void panthor_mmu_irq_handler(struct panthor_device *ptdev, u32 status)
 			access_type, access_type_name(ptdev, fault_status),
 			source_id);
 
+		/* We don't handle VM faults at the moment, so let's just clear the
+		 * interrupt and let the writer/reader crash.
+		 * Note that COMPLETED irqs are never cleared, but this is fine
+		 * because they are always masked.
+		 */
+		gpu_write(ptdev, MMU_INT_CLEAR, mask);
+
 		/* Ignore MMU interrupts on this AS until it's been
 		 * re-enabled.
 		 */
-- 
2.49.0

Re: [PATCH v3 4/5] drm/panthor: Let IRQ handlers clear the interrupts themselves

[Steven Price]

On 04/04/2025 09:09, Boris Brezillon wrote:
> MMU handler needs to be in control of the job interrupt clears because
> clearing the interrupt also unblocks the writer/reader that triggered
> the fault, and we don't want it to be unblocked until we've had a chance
> to process the IRQ.
> 
> Since clearing the clearing is just one line, let's make it explicit
> instead of doing it in the generic code path.
> 
> Note that this commit changes the existing behavior in that the MMU
> COMPLETED irqs are no longer cleared, which is fine because they are
> masked, so we're not risking an interrupt flood.
> 
> Changes in v3:
> - Mention the fact we no longer clear MMU COMPLETED irqs

Thanks!

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

> - Add Liviu's R-b
> 
> Changes in v2:
> - Move the MMU_INT_CLEAR around
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
> ---
>  drivers/gpu/drm/panthor/panthor_device.h | 2 --
>  drivers/gpu/drm/panthor/panthor_fw.c     | 2 ++
>  drivers/gpu/drm/panthor/panthor_gpu.c    | 2 ++
>  drivers/gpu/drm/panthor/panthor_mmu.c    | 7 +++++++
>  4 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> index da6574021664..4c27b6d85f46 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.h
> +++ b/drivers/gpu/drm/panthor/panthor_device.h
> @@ -383,8 +383,6 @@ static irqreturn_t panthor_ ## __name ## _irq_threaded_handler(int irq, void *da
>  		if (!status)									\
>  			break;									\
>  												\
> -		gpu_write(ptdev, __reg_prefix ## _INT_CLEAR, status);				\
> -												\
>  		__handler(ptdev, status);							\
>  		ret = IRQ_HANDLED;								\
>  	}											\
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 0f52766a3120..446bb377b953 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -1008,6 +1008,8 @@ static void panthor_fw_init_global_iface(struct panthor_device *ptdev)
>  
>  static void panthor_job_irq_handler(struct panthor_device *ptdev, u32 status)
>  {
> +	gpu_write(ptdev, JOB_INT_CLEAR, status);
> +
>  	if (!ptdev->fw->booted && (status & JOB_INT_GLOBAL_IF))
>  		ptdev->fw->booted = true;
>  
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
> index 671049020afa..32d678a0114e 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -150,6 +150,8 @@ static void panthor_gpu_init_info(struct panthor_device *ptdev)
>  
>  static void panthor_gpu_irq_handler(struct panthor_device *ptdev, u32 status)
>  {
> +	gpu_write(ptdev, GPU_INT_CLEAR, status);
> +
>  	if (status & GPU_IRQ_FAULT) {
>  		u32 fault_status = gpu_read(ptdev, GPU_FAULT_STATUS);
>  		u64 address = ((u64)gpu_read(ptdev, GPU_FAULT_ADDR_HI) << 32) |
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index 7cca97d298ea..0ba76982d45b 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -1710,6 +1710,13 @@ static void panthor_mmu_irq_handler(struct panthor_device *ptdev, u32 status)
>  			access_type, access_type_name(ptdev, fault_status),
>  			source_id);
>  
> +		/* We don't handle VM faults at the moment, so let's just clear the
> +		 * interrupt and let the writer/reader crash.
> +		 * Note that COMPLETED irqs are never cleared, but this is fine
> +		 * because they are always masked.
> +		 */
> +		gpu_write(ptdev, MMU_INT_CLEAR, mask);
> +
>  		/* Ignore MMU interrupts on this AS until it's been
>  		 * re-enabled.
>  		 */

[PATCH v3 5/5] drm/panthor: Don't update MMU_INT_MASK in panthor_mmu_irq_handler()

[Boris Brezillon]

Interrupts are automatically unmasked in
panthor_mmu_irq_threaded_handler() when the handler returns. Unmasking
prematurely might generate spurious interrupts if the IRQ line is
shared.

Changes in v2:
- New patch

Changes in v3:
- Add R-bs

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 0ba76982d45b..dc173c6edde0 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -1721,7 +1721,6 @@ static void panthor_mmu_irq_handler(struct panthor_device *ptdev, u32 status)
 		 * re-enabled.
 		 */
 		ptdev->mmu->irq.mask = new_int_mask;
-		gpu_write(ptdev, MMU_INT_MASK, new_int_mask);
 
 		if (ptdev->mmu->as.slots[as].vm)
 			ptdev->mmu->as.slots[as].vm->unhandled_fault = true;
-- 
2.49.0

Re: [PATCH v3 0/5] drm/panthor: Misc fixes

[Boris Brezillon]

On Fri,  4 Apr 2025 10:09:28 +0200
Boris Brezillon <boris.brezillon@collabora.com> wrote:

> Hello,
> 
> This is a collection of fixes for bugs found while working on adding
> JM support to panthor. Those are not particularly tied to JM support
> and are worth having regardless.
> 
> Note that the last two don't have Fixes tag because they fix issues
> we can't really hit with the current implementation (no fault
> handling, and no shared irq line).
> 
> Changelog available in each patch if you're interested.
> 
> Regards,
> 
> Boris
> 
> Boris Brezillon (5):
>   drm/panthor: Fix GPU_COHERENCY_ACE[_LITE] definitions
>   drm/panthor: Call panthor_gpu_coherency_init() after PM resume()
>   drm/panthor: Update panthor_mmu::irq::mask when needed
>   drm/panthor: Let IRQ handlers clear the interrupts themselves
>   drm/panthor: Don't update MMU_INT_MASK in panthor_mmu_irq_handler()

Queued to drm-misc-next.

> 
>  drivers/gpu/drm/panthor/panthor_device.c | 8 ++++----
>  drivers/gpu/drm/panthor/panthor_device.h | 2 --
>  drivers/gpu/drm/panthor/panthor_fw.c     | 2 ++
>  drivers/gpu/drm/panthor/panthor_gpu.c    | 2 ++
>  drivers/gpu/drm/panthor/panthor_mmu.c    | 9 ++++++++-
>  drivers/gpu/drm/panthor/panthor_regs.h   | 4 ++--
>  6 files changed, 18 insertions(+), 9 deletions(-)
>