linux-kernel - Re: [PATCH v7 09/43] drm/mediatek: mtk_dpi: Explicitly manage TVD clock in power on/off

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Message-ID: <CAAOTY__zrRM9oyDtuDAzJ+ddOU2as2-vy9FkGs_Wzqjo_==RvA@mail.gmail.com>
Date: Sun, 2 Mar 2025 22:05:50 +0800
From: Chun-Kuang Hu <chunkuang.hu@...nel.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: chunkuang.hu@...nel.org, p.zabel@...gutronix.de, airlied@...il.com, 
	simona@...ll.ch, maarten.lankhorst@...ux.intel.com, mripard@...nel.org, 
	tzimmermann@...e.de, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	matthias.bgg@...il.com, ck.hu@...iatek.com, jitao.shi@...iatek.com, 
	jie.qiu@...iatek.com, junzhi.zhao@...iatek.com, 
	dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, kernel@...labora.com, 
	dmitry.baryshkov@...aro.org, lewis.liao@...iatek.com, 
	ives.chenjh@...iatek.com, tommyyl.chen@...iatek.com, 
	jason-jh.lin@...iatek.com
Subject: Re: [PATCH v7 09/43] drm/mediatek: mtk_dpi: Explicitly manage TVD
 clock in power on/off

Hi, Angelo:

AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com> 於
2025年2月17日 週一 下午11:49寫道：
>
> In preparation for adding support for MT8195's HDMI reserved
> DPI, add calls to clk_prepare_enable() / clk_disable_unprepare()
> for the TVD clock: in this particular case, the aforementioned
> clock is not (and cannot be) parented to neither pixel or engine
> clocks hence it won't get enabled automatically by the clock
> framework.
>
> Please note that on all of the currently supported MediaTek
> platforms, the TVD clock is always a parent of either pixel or
> engine clocks, and this means that the common clock framework
> is already enabling this clock before the children.
> On such platforms, this commit will only increase the refcount
> of the TVD clock without any functional change.

Applied to mediatek-drm-next [1], thanks.

[1] https://web.git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next

Regards,
Chun-Kuang.

>
> Reviewed-by: CK Hu <ck.hu@...iatek.com>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index e12dc73ed79c..ee952785866c 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -499,6 +499,7 @@ static void mtk_dpi_power_off(struct mtk_dpi *dpi)
>
>         mtk_dpi_disable(dpi);
>         clk_disable_unprepare(dpi->pixel_clk);
> +       clk_disable_unprepare(dpi->tvd_clk);
>         clk_disable_unprepare(dpi->engine_clk);
>  }
>
> @@ -515,6 +516,12 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi)
>                 goto err_refcount;
>         }
>
> +       ret = clk_prepare_enable(dpi->tvd_clk);
> +       if (ret) {
> +               dev_err(dpi->dev, "Failed to enable tvd pll: %d\n", ret);
> +               goto err_engine;
> +       }
> +
>         ret = clk_prepare_enable(dpi->pixel_clk);
>         if (ret) {
>                 dev_err(dpi->dev, "Failed to enable pixel clock: %d\n", ret);
> @@ -524,6 +531,8 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi)
>         return 0;
>
>  err_pixel:
> +       clk_disable_unprepare(dpi->tvd_clk);
> +err_engine:
>         clk_disable_unprepare(dpi->engine_clk);
>  err_refcount:
>         dpi->refcount--;
> --
> 2.48.1
>