linux-kernel - Re: [PATCH V2 1/2] arm64: dts: imx8mp: Fix SDMA2/3 clocks

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Message-ID: <CAOMZO5Cw5bFD3U6KXkuobUCmZbjYsL_=gZobeKFXGQo55aA+Vg@mail.gmail.com>
Date:   Tue, 15 Aug 2023 22:57:57 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Adam Ford <aford173@...il.com>
Cc:     linux-arm-kernel@...ts.infradead.org, aford@...conembedded.com,
        Lucas Stach <l.stach@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 1/2] arm64: dts: imx8mp: Fix SDMA2/3 clocks

Hi Adam,

On Tue, Aug 15, 2023 at 8:11 PM Adam Ford <aford173@...il.com> wrote:
>
> A previous patch to remove the Audio clocks from the main clock node

Nit: Instead of referring to "A previous patch", it would be clearer
to explicitly
refer to the actual commit.

> was intended to force people to setup the audio PLL clocks per board
> instead of having a common set of rates since not all boards may use
> the various audio PLL clocks for audio devices.
>
> Unfortunately, with this parenting removed, the SDMA2 and SDMA3
> clocks were slowed to 24MHz because the SDMA2/3 clocks are controlled
> via the audio_blk_ctrl which is clocked from IMX8MP_CLK_AUDIO_ROOT,
> and that clock is enabled by pgc_audio.
>
> Per the TRM, "The SDMA2/3 target frequency is 400MHz IPG and 400MHz
> AHB, always 1:1 mode, to make sure there is enough throughput for all
> the audio use cases."
>
> Instead of cluttering the clock node, place the clock rate and parent
> information into the pgc_audio node.
>
> With the parenting and clock rates restored for  IMX8MP_CLK_AUDIO_AHB,
> and IMX8MP_CLK_AUDIO_AXI_SRC, it appears the SDMA2 and SDMA3 run at
> 400MHz again.
>
> Fixes: 16c984524862 ("arm64: dts: imx8mp: don't initialize audio clocks from CCM node")
> Signed-off-by: Adam Ford <aford173@...il.com>
> Reviewed-by: Lucas Stach <l.stach@...gutronix.de>

Reviewed-by: Fabio Estevam <festevam@...il.com>