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@xxxxxxxxxxxxx>
Reviewed-by: Steven Price <steven.price@xxxxxxx>
> ---
> 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");
> }
