linux-kernel - Re: [PATCH v4 1/3] drm/panfrost: Ignore core_mask for poweroff and disable PWRTRANS irq

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Message-ID: <4c70768c-c127-4577-9170-51857e657d19@samsung.com>
Date:   Mon, 4 Dec 2023 17:05:16 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        boris.brezillon@...labora.com
Cc:     robh@...nel.org, steven.price@....com,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com, krzysztof.kozlowski@...aro.org
Subject: Re: [PATCH v4 1/3] drm/panfrost: Ignore core_mask for poweroff and
 disable PWRTRANS irq

On 04.12.2023 12:42, AngeloGioacchino Del Regno wrote:
> Some SoCs may be equipped with a GPU containing two core groups
> and this is exactly the case of Samsung's Exynos 5422 featuring
> an ARM Mali-T628 MP6 GPU: the support for this GPU in Panfrost
> is partial, as this driver currently supports using only one
> core group and that's reflected on all parts of it, including
> the power on (and power off, previously to this patch) function.
>
> The issue with this is that even though executing the soft reset
> operation should power off all cores unconditionally, on at least
> one platform we're seeing a crash that seems to be happening due
> to an interrupt firing which may be because we are calling power
> transition only on the first core group, leaving the second one
> unchanged, or because ISR execution was pending before entering
> the panfrost_gpu_power_off() function and executed after powering
> off the GPU cores, or all of the above.
>
> Finally, solve this by:
>   - Avoid to enable the power transition interrupt on reset; and
>   - Ignoring the core_mask and ask the GPU to poweroff both core groups
>
> Fixes: 22aa1a209018 ("drm/panfrost: Really power off GPU cores in panfrost_gpu_power_off()")
> Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
> Reviewed-by: Steven Price <steven.price@....com>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>


Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>


> ---
>   drivers/gpu/drm/panfrost/panfrost_gpu.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
>
> ...

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland