linux-kernel - Re: [PATCH] drm/panfrost: increase readl_relaxed_poll

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Date:   Fri, 9 Oct 2020 16:54:19 +0100
From:   Steven Price <steven.price@....com>
To:     Christian Hewitt <christianshewitt@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/panfrost: increase readl_relaxed_poll_timeout values

On 08/10/2020 15:17, Christian Hewitt wrote:
> Amlogic SoC devices report the following errors frequently causing excessive
> dmesg log spam and early log rotataion, although the errors appear to be
> harmless as everything works fine:
> 
> [    7.202702] panfrost ffe40000.gpu: error powering up gpu L2
> [    7.203760] panfrost ffe40000.gpu: error powering up gpu shader
> 
> ARM staff have advised increasing the timeout values to eliminate the errors
> in most normal scenarios, and testing with several different G31/G52 devices
> shows 20000 to be a reliable value.
> 
> Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
> Suggested-by: Steven Price <steven.price@....com>
> Signed-off-by: Christian Hewitt <christianshewitt@...il.com>

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

I'll push this to drm-misc-next-fixes so it should coincide with the 
Bifrost support already in drm-misc-next.

Steve

> ---
>   drivers/gpu/drm/panfrost/panfrost_gpu.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> index e1b2a3376624..2aae636f1cf5 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> @@ -325,13 +325,13 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev)
>   	/* Just turn on everything for now */
>   	gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present);
>   	ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO,
> -		val, val == pfdev->features.l2_present, 100, 1000);
> +		val, val == pfdev->features.l2_present, 100, 20000);
>   	if (ret)
>   		dev_err(pfdev->dev, "error powering up gpu L2");
>   
>   	gpu_write(pfdev, SHADER_PWRON_LO, pfdev->features.shader_present);
>   	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO,
> -		val, val == pfdev->features.shader_present, 100, 1000);
> +		val, val == pfdev->features.shader_present, 100, 20000);
>   	if (ret)
>   		dev_err(pfdev->dev, "error powering up gpu shader");
>   
>