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[PATCH 2/3] drm/panthor: Explicitly set the coherency mode

Akash Goel posted 3 patches 1 month ago
There is a newer version of this series
[PATCH 2/3] drm/panthor: Explicitly set the coherency mode
Posted by Akash Goel 1 month ago 
This commit fixes the potential misalignment between the value of device
tree property "dma-coherent" and default value of COHERENCY_ENABLE
register.
Panthor driver didn't explicitly program the COHERENCY_ENABLE register
with the desired coherency mode. The default value of COHERENCY_ENABLE
register is implementation defined, so it may not be always aligned with
the "dma-coherent" property value.
The commit also checks the COHERENCY_FEATURES register to confirm that
the coherency protocol is actually supported or not.

Signed-off-by: Akash Goel <akash.goel@arm.com>
---
 drivers/gpu/drm/panthor/panthor_device.c | 22 +++++++++++++++++++++-
 drivers/gpu/drm/panthor/panthor_gpu.c    |  9 +++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 4082c8f2951d..984615f4ed27 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -22,6 +22,24 @@
 #include "panthor_regs.h"
 #include "panthor_sched.h"
 
+static int panthor_gpu_coherency_init(struct panthor_device *ptdev)
+{
+	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
+
+	if (!ptdev->coherent)
+		return 0;
+
+	/* Check if the ACE-Lite coherency protocol is actually supported by the GPU.
+	 * ACE protocol has never been supported for command stream frontend GPUs.
+	 */
+	if ((gpu_read(ptdev, GPU_COHERENCY_FEATURES) &
+		      GPU_COHERENCY_PROT_BIT(ACE_LITE)))
+		return 0;
+
+	drm_err(&ptdev->base, "Coherency not supported by the device");
+	return -ENOTSUPP;
+}
+
 static int panthor_clk_init(struct panthor_device *ptdev)
 {
 	ptdev->clks.core = devm_clk_get(ptdev->base.dev, NULL);
@@ -156,7 +174,9 @@ int panthor_device_init(struct panthor_device *ptdev)
 	struct page *p;
 	int ret;
 
-	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
+	ret = panthor_gpu_coherency_init(ptdev);
+	if (ret)
+		return ret;
 
 	init_completion(&ptdev->unplug.done);
 	ret = drmm_mutex_init(&ptdev->base, &ptdev->unplug.lock);
diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
index 5251d8764e7d..1e24f08a519a 100644
--- a/drivers/gpu/drm/panthor/panthor_gpu.c
+++ b/drivers/gpu/drm/panthor/panthor_gpu.c
@@ -77,6 +77,12 @@ static const struct panthor_model gpu_models[] = {
 	 GPU_IRQ_RESET_COMPLETED | \
 	 GPU_IRQ_CLEAN_CACHES_COMPLETED)
 
+static void panthor_gpu_coherency_set(struct panthor_device *ptdev)
+{
+	gpu_write(ptdev, GPU_COHERENCY_PROTOCOL,
+		ptdev->coherent ? GPU_COHERENCY_PROT_BIT(ACE_LITE) : GPU_COHERENCY_NONE);
+}
+
 static void panthor_gpu_init_info(struct panthor_device *ptdev)
 {
 	const struct panthor_model *model;
@@ -365,6 +371,9 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev)
 			      hweight64(ptdev->gpu_info.shader_present));
 	}
 
+	/* Set the desired coherency mode before the power up of L2 */
+	panthor_gpu_coherency_set(ptdev);
+
 	return panthor_gpu_power_on(ptdev, L2, 1, 20000);
 }
 
-- 
2.25.1
Re: [PATCH 2/3] drm/panthor: Explicitly set the coherency mode
Posted by Steven Price 1 month ago 
On 24/10/2024 15:54, Akash Goel wrote:
> This commit fixes the potential misalignment between the value of device
> tree property "dma-coherent" and default value of COHERENCY_ENABLE
> register.
> Panthor driver didn't explicitly program the COHERENCY_ENABLE register
> with the desired coherency mode. The default value of COHERENCY_ENABLE
> register is implementation defined, so it may not be always aligned with
> the "dma-coherent" property value.
> The commit also checks the COHERENCY_FEATURES register to confirm that
> the coherency protocol is actually supported or not.
> 
> Signed-off-by: Akash Goel <akash.goel@arm.com>

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

> ---
>  drivers/gpu/drm/panthor/panthor_device.c | 22 +++++++++++++++++++++-
>  drivers/gpu/drm/panthor/panthor_gpu.c    |  9 +++++++++
>  2 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index 4082c8f2951d..984615f4ed27 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -22,6 +22,24 @@
>  #include "panthor_regs.h"
>  #include "panthor_sched.h"
>  
> +static int panthor_gpu_coherency_init(struct panthor_device *ptdev)
> +{
> +	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
> +
> +	if (!ptdev->coherent)
> +		return 0;
> +
> +	/* Check if the ACE-Lite coherency protocol is actually supported by the GPU.
> +	 * ACE protocol has never been supported for command stream frontend GPUs.
> +	 */
> +	if ((gpu_read(ptdev, GPU_COHERENCY_FEATURES) &
> +		      GPU_COHERENCY_PROT_BIT(ACE_LITE)))
> +		return 0;
> +
> +	drm_err(&ptdev->base, "Coherency not supported by the device");
> +	return -ENOTSUPP;
> +}
> +
>  static int panthor_clk_init(struct panthor_device *ptdev)
>  {
>  	ptdev->clks.core = devm_clk_get(ptdev->base.dev, NULL);
> @@ -156,7 +174,9 @@ int panthor_device_init(struct panthor_device *ptdev)
>  	struct page *p;
>  	int ret;
>  
> -	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
> +	ret = panthor_gpu_coherency_init(ptdev);
> +	if (ret)
> +		return ret;
>  
>  	init_completion(&ptdev->unplug.done);
>  	ret = drmm_mutex_init(&ptdev->base, &ptdev->unplug.lock);
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
> index 5251d8764e7d..1e24f08a519a 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -77,6 +77,12 @@ static const struct panthor_model gpu_models[] = {
>  	 GPU_IRQ_RESET_COMPLETED | \
>  	 GPU_IRQ_CLEAN_CACHES_COMPLETED)
>  
> +static void panthor_gpu_coherency_set(struct panthor_device *ptdev)
> +{
> +	gpu_write(ptdev, GPU_COHERENCY_PROTOCOL,
> +		ptdev->coherent ? GPU_COHERENCY_PROT_BIT(ACE_LITE) : GPU_COHERENCY_NONE);
> +}
> +
>  static void panthor_gpu_init_info(struct panthor_device *ptdev)
>  {
>  	const struct panthor_model *model;
> @@ -365,6 +371,9 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev)
>  			      hweight64(ptdev->gpu_info.shader_present));
>  	}
>  
> +	/* Set the desired coherency mode before the power up of L2 */
> +	panthor_gpu_coherency_set(ptdev);
> +
>  	return panthor_gpu_power_on(ptdev, L2, 1, 20000);
>  }
>
Re: [PATCH 2/3] drm/panthor: Explicitly set the coherency mode
Posted by Liviu Dudau 1 month ago 
On Thu, Oct 24, 2024 at 03:54:31PM +0100, Akash Goel wrote:
> This commit fixes the potential misalignment between the value of device
> tree property "dma-coherent" and default value of COHERENCY_ENABLE
> register.
> Panthor driver didn't explicitly program the COHERENCY_ENABLE register
> with the desired coherency mode. The default value of COHERENCY_ENABLE
> register is implementation defined, so it may not be always aligned with
> the "dma-coherent" property value.
> The commit also checks the COHERENCY_FEATURES register to confirm that
> the coherency protocol is actually supported or not.
> 
> Signed-off-by: Akash Goel <akash.goel@arm.com>

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

Best regards,
Liviu

> ---
>  drivers/gpu/drm/panthor/panthor_device.c | 22 +++++++++++++++++++++-
>  drivers/gpu/drm/panthor/panthor_gpu.c    |  9 +++++++++
>  2 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index 4082c8f2951d..984615f4ed27 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -22,6 +22,24 @@
>  #include "panthor_regs.h"
>  #include "panthor_sched.h"
>  
> +static int panthor_gpu_coherency_init(struct panthor_device *ptdev)
> +{
> +	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
> +
> +	if (!ptdev->coherent)
> +		return 0;
> +
> +	/* Check if the ACE-Lite coherency protocol is actually supported by the GPU.
> +	 * ACE protocol has never been supported for command stream frontend GPUs.
> +	 */
> +	if ((gpu_read(ptdev, GPU_COHERENCY_FEATURES) &
> +		      GPU_COHERENCY_PROT_BIT(ACE_LITE)))
> +		return 0;
> +
> +	drm_err(&ptdev->base, "Coherency not supported by the device");
> +	return -ENOTSUPP;
> +}
> +
>  static int panthor_clk_init(struct panthor_device *ptdev)
>  {
>  	ptdev->clks.core = devm_clk_get(ptdev->base.dev, NULL);
> @@ -156,7 +174,9 @@ int panthor_device_init(struct panthor_device *ptdev)
>  	struct page *p;
>  	int ret;
>  
> -	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
> +	ret = panthor_gpu_coherency_init(ptdev);
> +	if (ret)
> +		return ret;
>  
>  	init_completion(&ptdev->unplug.done);
>  	ret = drmm_mutex_init(&ptdev->base, &ptdev->unplug.lock);
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
> index 5251d8764e7d..1e24f08a519a 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -77,6 +77,12 @@ static const struct panthor_model gpu_models[] = {
>  	 GPU_IRQ_RESET_COMPLETED | \
>  	 GPU_IRQ_CLEAN_CACHES_COMPLETED)
>  
> +static void panthor_gpu_coherency_set(struct panthor_device *ptdev)
> +{
> +	gpu_write(ptdev, GPU_COHERENCY_PROTOCOL,
> +		ptdev->coherent ? GPU_COHERENCY_PROT_BIT(ACE_LITE) : GPU_COHERENCY_NONE);
> +}
> +
>  static void panthor_gpu_init_info(struct panthor_device *ptdev)
>  {
>  	const struct panthor_model *model;
> @@ -365,6 +371,9 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev)
>  			      hweight64(ptdev->gpu_info.shader_present));
>  	}
>  
> +	/* Set the desired coherency mode before the power up of L2 */
> +	panthor_gpu_coherency_set(ptdev);
> +
>  	return panthor_gpu_power_on(ptdev, L2, 1, 20000);
>  }
>  
> -- 
> 2.25.1
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯
Re: [PATCH 2/3] drm/panthor: Explicitly set the coherency mode
Posted by Boris Brezillon 1 month ago 
On Thu, 24 Oct 2024 15:54:31 +0100
Akash Goel <akash.goel@arm.com> wrote:

> This commit fixes the potential misalignment between the value of device
> tree property "dma-coherent" and default value of COHERENCY_ENABLE
> register.
> Panthor driver didn't explicitly program the COHERENCY_ENABLE register
> with the desired coherency mode. The default value of COHERENCY_ENABLE
> register is implementation defined, so it may not be always aligned with
> the "dma-coherent" property value.
> The commit also checks the COHERENCY_FEATURES register to confirm that
> the coherency protocol is actually supported or not.
> 
> Signed-off-by: Akash Goel <akash.goel@arm.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/gpu/drm/panthor/panthor_device.c | 22 +++++++++++++++++++++-
>  drivers/gpu/drm/panthor/panthor_gpu.c    |  9 +++++++++
>  2 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index 4082c8f2951d..984615f4ed27 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -22,6 +22,24 @@
>  #include "panthor_regs.h"
>  #include "panthor_sched.h"
>  
> +static int panthor_gpu_coherency_init(struct panthor_device *ptdev)
> +{
> +	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
> +
> +	if (!ptdev->coherent)
> +		return 0;
> +
> +	/* Check if the ACE-Lite coherency protocol is actually supported by the GPU.
> +	 * ACE protocol has never been supported for command stream frontend GPUs.
> +	 */
> +	if ((gpu_read(ptdev, GPU_COHERENCY_FEATURES) &
> +		      GPU_COHERENCY_PROT_BIT(ACE_LITE)))
> +		return 0;
> +
> +	drm_err(&ptdev->base, "Coherency not supported by the device");
> +	return -ENOTSUPP;
> +}
> +
>  static int panthor_clk_init(struct panthor_device *ptdev)
>  {
>  	ptdev->clks.core = devm_clk_get(ptdev->base.dev, NULL);
> @@ -156,7 +174,9 @@ int panthor_device_init(struct panthor_device *ptdev)
>  	struct page *p;
>  	int ret;
>  
> -	ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
> +	ret = panthor_gpu_coherency_init(ptdev);
> +	if (ret)
> +		return ret;
>  
>  	init_completion(&ptdev->unplug.done);
>  	ret = drmm_mutex_init(&ptdev->base, &ptdev->unplug.lock);
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
> index 5251d8764e7d..1e24f08a519a 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -77,6 +77,12 @@ static const struct panthor_model gpu_models[] = {
>  	 GPU_IRQ_RESET_COMPLETED | \
>  	 GPU_IRQ_CLEAN_CACHES_COMPLETED)
>  
> +static void panthor_gpu_coherency_set(struct panthor_device *ptdev)
> +{
> +	gpu_write(ptdev, GPU_COHERENCY_PROTOCOL,
> +		ptdev->coherent ? GPU_COHERENCY_PROT_BIT(ACE_LITE) : GPU_COHERENCY_NONE);
> +}
> +
>  static void panthor_gpu_init_info(struct panthor_device *ptdev)
>  {
>  	const struct panthor_model *model;
> @@ -365,6 +371,9 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev)
>  			      hweight64(ptdev->gpu_info.shader_present));
>  	}
>  
> +	/* Set the desired coherency mode before the power up of L2 */
> +	panthor_gpu_coherency_set(ptdev);
> +
>  	return panthor_gpu_power_on(ptdev, L2, 1, 20000);
>  }
>

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