linux-kernel - Re: [PATCH] drm/panfrost: Really power off GPU cores in panfrost_gpu_power

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Message-ID: <7928524a-b581-483b-b1a1-6ffd719ce650@arm.com>
Date:   Wed, 8 Nov 2023 13:20:00 +0000
From:   Steven Price <steven.price@....com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        boris.brezillon@...labora.com
Cc:     robh@...nel.org, 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, wenst@...omium.org,
        kernel@...labora.com
Subject: Re: [PATCH] drm/panfrost: Really power off GPU cores in
 panfrost_gpu_power_off()

On 02/11/2023 14:15, AngeloGioacchino Del Regno wrote:
> The layout of the registers {TILER,SHADER,L2}_PWROFF_LO, used to request
> powering off cores, is the same as the {TILER,SHADER,L2}_PWRON_LO ones:
> this means that in order to request poweroff of cores, we are supposed
> to write a bitmask of cores that should be powered off!
> This means that the panfrost_gpu_power_off() function has always been
> doing nothing.
> 
> Fix powering off the GPU by writing a bitmask of the cores to poweroff
> to the relevant PWROFF_LO registers and then check that the transition
> (from ON to OFF) has finished by polling the relevant PWRTRANS_LO
> registers.
> 
> While at it, in order to avoid code duplication, move the core mask
> logic from panfrost_gpu_power_on() to a new panfrost_get_core_mask()
> function, used in both poweron and poweroff.
> 
> Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

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

Thanks,

Steve