diff mbox series

[v2,2/6] drm/panfrost: Tighten polling for soft reset and power on

Message ID 20231102142643.75288-3-angelogioacchino.delregno@collabora.com
State New
Headers
Series drm/panfrost: Turn off clocks and regulators in PM |

Commit Message

AngeloGioacchino Del Regno Nov. 2, 2023, 2:26 p.m. UTC 
  In many cases, soft reset takes more than 1 microsecond, but definitely
less than 10; moreover in the poweron flow, tilers, shaders and l2 will
become ready (each) in less than 10 microseconds as well.

Even in the cases (at least on my platforms, rarely) in which those take
more than 10 microseconds, it's very unlikely to see both soft reset and
poweron to take more than 70 microseconds.

Shorten the polling delay to 10 microseconds to consistently reduce the
runtime resume time of the GPU.

As an indicative example, measurements taken on a MediaTek MT8195 SoC

Average runtime resume time in nanoseconds before this commit:
GDM, user selection up/down:            88435ns
GDM, Text Entry (typing user/password): 91489ns
GNOME Desktop, idling, GKRELLM running: 73200ns

After this commit:

GDM: user selection up/down:            26690ns
GDM: Text Entry (typing user/password): 27917ns
GNOME Desktop, idling, GKRELLM running:	25304ns

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_gpu.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Steven Price Nov. 8, 2023, 3:44 p.m. UTC | #1 
On 02/11/2023 14:26, AngeloGioacchino Del Regno wrote:
> In many cases, soft reset takes more than 1 microsecond, but definitely
> less than 10; moreover in the poweron flow, tilers, shaders and l2 will
> become ready (each) in less than 10 microseconds as well.
> 
> Even in the cases (at least on my platforms, rarely) in which those take
> more than 10 microseconds, it's very unlikely to see both soft reset and
> poweron to take more than 70 microseconds.
> 
> Shorten the polling delay to 10 microseconds to consistently reduce the
> runtime resume time of the GPU.
> 
> As an indicative example, measurements taken on a MediaTek MT8195 SoC
> 
> Average runtime resume time in nanoseconds before this commit:
> GDM, user selection up/down:            88435ns
> GDM, Text Entry (typing user/password): 91489ns
> GNOME Desktop, idling, GKRELLM running: 73200ns
> 
> After this commit:
> 
> GDM: user selection up/down:            26690ns
> GDM: Text Entry (typing user/password): 27917ns
> GNOME Desktop, idling, GKRELLM running:	25304ns
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

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

> ---
>  drivers/gpu/drm/panfrost/panfrost_gpu.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> index 7e9e2cf26e4d..e264e8c2252d 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> @@ -63,7 +63,7 @@ int panfrost_gpu_soft_reset(struct panfrost_device *pfdev)
>  
>  	gpu_write(pfdev, GPU_CMD, GPU_CMD_SOFT_RESET);
>  	ret = readl_relaxed_poll_timeout(pfdev->iomem + GPU_INT_RAWSTAT,
> -		val, val & GPU_IRQ_RESET_COMPLETED, 100, 10000);
> +		val, val & GPU_IRQ_RESET_COMPLETED, 10, 10000);
>  	if (ret) {
>  		dev_err(pfdev->dev, "gpu soft reset timed out, attempting hard reset\n");
>  
> @@ -403,7 +403,7 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev)
>  	gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present & core_mask);
>  	ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO,
>  		val, val == (pfdev->features.l2_present & core_mask),
> -		100, 20000);
> +		10, 20000);
>  	if (ret)
>  		dev_err(pfdev->dev, "error powering up gpu L2");
>  
> @@ -411,13 +411,13 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev)
>  		  pfdev->features.shader_present & core_mask);
>  	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO,
>  		val, val == (pfdev->features.shader_present & core_mask),
> -		100, 20000);
> +		10, 20000);
>  	if (ret)
>  		dev_err(pfdev->dev, "error powering up gpu shader");
>  
>  	gpu_write(pfdev, TILER_PWRON_LO, pfdev->features.tiler_present);
>  	ret = readl_relaxed_poll_timeout(pfdev->iomem + TILER_READY_LO,
> -		val, val == pfdev->features.tiler_present, 100, 1000);
> +		val, val == pfdev->features.tiler_present, 10, 1000);
>  	if (ret)
>  		dev_err(pfdev->dev, "error powering up gpu tiler");
>  }
diff mbox series

Patch

diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
index 7e9e2cf26e4d..e264e8c2252d 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
@@ -63,7 +63,7 @@  int panfrost_gpu_soft_reset(struct panfrost_device *pfdev)
 
 	gpu_write(pfdev, GPU_CMD, GPU_CMD_SOFT_RESET);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + GPU_INT_RAWSTAT,
-		val, val & GPU_IRQ_RESET_COMPLETED, 100, 10000);
+		val, val & GPU_IRQ_RESET_COMPLETED, 10, 10000);
 	if (ret) {
 		dev_err(pfdev->dev, "gpu soft reset timed out, attempting hard reset\n");
 
@@ -403,7 +403,7 @@  void panfrost_gpu_power_on(struct panfrost_device *pfdev)
 	gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present & core_mask);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO,
 		val, val == (pfdev->features.l2_present & core_mask),
-		100, 20000);
+		10, 20000);
 	if (ret)
 		dev_err(pfdev->dev, "error powering up gpu L2");
 
@@ -411,13 +411,13 @@  void panfrost_gpu_power_on(struct panfrost_device *pfdev)
 		  pfdev->features.shader_present & core_mask);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO,
 		val, val == (pfdev->features.shader_present & core_mask),
-		100, 20000);
+		10, 20000);
 	if (ret)
 		dev_err(pfdev->dev, "error powering up gpu shader");
 
 	gpu_write(pfdev, TILER_PWRON_LO, pfdev->features.tiler_present);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + TILER_READY_LO,
-		val, val == pfdev->features.tiler_present, 100, 1000);
+		val, val == pfdev->features.tiler_present, 10, 1000);
 	if (ret)
 		dev_err(pfdev->dev, "error powering up gpu tiler");
 }