From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
To: Chen-Yu Tsai <wenst@chromium.org>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
Matthias Brugger <matthias.bgg@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Chun-Jie Chen <chun-jie.chen@mediatek.com>,
Miles Chen <miles.chen@mediatek.com>,
linux-clk@vger.kernel.org, devicetree@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 4/4] clk: mediatek: mt8183: Add clk mux notifier for MFG mux
Date: Mon, 23 May 2022 12:05:20 +0200 [thread overview]
Message-ID: <29641040-f6f1-a3c1-cad4-96911c8e38a8@collabora.com> (raw)
In-Reply-To: <20220523085923.1430470-5-wenst@chromium.org>
Il 23/05/22 10:59, Chen-Yu Tsai ha scritto:
> When the MFG PLL clock, which is upstream of the MFG clock, is changed,
> the downstream clock and consumers need to be switched away from the PLL
> over to a stable clock to avoid glitches.
>
> This is done through the use of the newly added clk mux notifier. The
> notifier is set on the mux itself instead of the upstream PLL, but in
> practice this works, as the rate change notifitcations are propogated
> throughout the sub-tree hanging off the PLL. Just before rate changes,
> the MFG mux is temporarily and transparently switched to the 26 MHz
> main crystal. After the rate change, the mux is switched back.
>
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
prev parent reply other threads:[~2022-05-23 10:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 8:59 [PATCH v2 0/4] clk: mediatek: mt8183: Fix GPU/MFG clock rate changing Chen-Yu Tsai
2022-05-23 8:59 ` [PATCH v2 1/4] arm64: dts: mt8183: Fix Mali GPU clock Chen-Yu Tsai
2022-05-23 10:04 ` AngeloGioacchino Del Regno
2022-05-23 8:59 ` [PATCH v2 2/4] clk: mediatek: mt8183: mfgcfg: Propagate rate changes to parent Chen-Yu Tsai
2022-05-23 10:04 ` AngeloGioacchino Del Regno
2022-05-23 8:59 ` [PATCH v2 3/4] clk: mediatek: mux: add clk notifier functions Chen-Yu Tsai
2022-05-23 10:04 ` AngeloGioacchino Del Regno
2022-05-23 10:20 ` Chen-Yu Tsai
2022-05-23 8:59 ` [PATCH v2 4/4] clk: mediatek: mt8183: Add clk mux notifier for MFG mux Chen-Yu Tsai
2022-05-23 10:05 ` AngeloGioacchino Del Regno [this message]
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