linux-kernel - Re: [PATCH v2 09/13] drm/sun4i: hdmi: Add support for controller hardware variants

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Date:   Tue, 26 Sep 2017 12:01:50 +0200
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Mark Brown <broonie@...nel.org>, David Airlie <airlied@...ux.ie>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 09/13] drm/sun4i: hdmi: Add support for controller
 hardware variants

On Tue, Sep 26, 2017 at 06:59:15AM +0000, Chen-Yu Tsai wrote:
> The HDMI controller found in earlier Allwinner SoCs have slight
> differences between the A10, A10s, and the A31:
> 
>   - Need different initial values for the PLL related registers
> 
>   - Different behavior of the DDC and TMDS clocks
> 
>   - Different register layout for the DDC portion
> 
>   - Separate DDC parent clock on the A31
> 
>   - Explicit reset control
> 
> For the A31, the HDMI TMDS clock has a different value offset for
> the divider. The HDMI DDC block is different from the one in the
> other SoCs. As far as the DDC clock goes, it has no pre-divider,
> as it is clocked from a slower parent clock, not the TMDS clock.
> The divider offset from the register value is different. And the
> clock control register is at a different offset.
> 
> A new variant data structure is created to store pointers to the
> above functions, structures, and the different initial values.
> Another flag notates whether there is a separate DDC parent clock.
> If not, the TMDS clock is passed to the DDC clock create function,
> as before.
> 
> Regmap fields are used to deal with the different register layout
> of the DDC block.
> 
> Signed-off-by: Chen-Yu Tsai <wens@...e.org>

Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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