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From:   Jernej =?utf-8?B?xaBrcmFiZWM=?= <jernej.skrabec@gmail.com>
To:     Maxime Ripard <mripard@kernel.org>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>, Chen-Yu Tsai <wens@csie.org>,
        Samuel Holland <samuel@sholland.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Roman Beranek <me@crly.cz>
Cc:     Frank Oltmanns <frank@oltmanns.dev>,
        Icenowy Zheng <icenowy@aosc.io>, Ondrej Jirman <megi@xff.cz>,
        devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev,
        linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/4] clk: sunxi-ng: a64: force select PLL_MIPI in TCON0 mux
Date:   Wed, 10 May 2023 20:43:29 +0200
Message-ID: <5674988.DvuYhMxLoT@jernej-laptop>
In-Reply-To: <20230505052110.67514-2-me@crly.cz>
References: <20230505052110.67514-1-me@crly.cz> <20230505052110.67514-2-me@crly.cz>
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Dne petek, 05. maj 2023 ob 07:21:07 CEST je Roman Beranek napisal(a):
> TCON0's source clock can be fed from either PLL_MIPI, or PLL_VIDEO0(2X),
> however MIPI DSI output only seems to work when PLL_MIPI is selected and
> thus the choice must be hardcoded in.
> 
> Currently, this driver can't propagate rate change from N-K-M clocks
> (such as PLL_MIPI) upwards. This prevents PLL_VIDEO0 from participating
> in setting of the TCON0 data clock rate, limiting the precision with
> which a target pixel clock can be matched.
> 
> For outputs with fixed TCON0 divider, that is DSI and LVDS, the dotclock
> can deviate up to 8% off target.
> 
> Signed-off-by: Roman Beranek <me@crly.cz>

Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Best regards,
Jernej