linux-kernel - Re: [PATCH v6 09/42] drm/mediatek: mtk_dpi: Explicitly manage TVD clock in power on/off

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Message-ID: <5eefa246f471f4b9382d6f20a9ea783136bd80c5.camel@mediatek.com>
Date: Fri, 14 Feb 2025 01:51:59 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
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Subject: Re: [PATCH v6 09/42] drm/mediatek: mtk_dpi: Explicitly manage TVD
 clock in power on/off

On Tue, 2025-02-11 at 12:33 +0100, AngeloGioacchino Del Regno wrote:
> External email : Please do not click links or open attachments until you have verified the sender or the content.
> 
> 
> 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.

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 5c15c8935916..67504eb874d2 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -501,6 +501,7 @@ 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);
>  }
> 
> @@ -517,6 +518,12 @@ 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);
> @@ -526,6 +533,8 @@ 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
>