linux-kernel - Re: [PATCH 4/5] drm/panfrost: add amlogic reset quirk callback

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Message-ID: <20200908191010.GB10568@kevin>
Date:   Tue, 8 Sep 2020 15:10:10 -0400
From:   Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     robh@...nel.org, tomeu.vizoso@...labora.com, steven.price@....com,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH 4/5] drm/panfrost: add amlogic reset quirk callback

> Since the documentation of the GPU cores are not public, we do not know what does these
> values, but they permit having a fully functional GPU running with Panfrost.

Since this is Amlogic magic, not specifically GPU, I'd rephrase this as
"Since the Amlogic's integration of the GPU cores with the SoC is not
publicly documented..."

> +	/*
> +	 * The Amlogic integrated Mali-T820, Mali-G31 & Mali-G52 needs
> +	 * these undocumented bits to be set in order to operate
> +	 * correctly.
> +	 * These GPU_PWR registers contains:
> +	 * "device-specific power control value"
> +	 */

PWR_OVERRIDE1 is the Amlogic specific value.

Per the name, for PWR_KEY, I'd do add "#define GPU_PWR_KEY_UNLOCK
0x2968A819" in panfrost-gpu.h so it's clear which value is which.

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