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

AngeloGioacchino Del Regno
2025-02-17T14:42:01Z

Il 14/02/25 04:31, CK Hu (胡俊光) ha scritto:
> On Fri, 2025-02-14 at 09:51 +0800, CK Hu wrote:
>> 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@mediatek.com>
>
> One question:
> MT8195 DPI clock is from HDMI, why need to contol TVD clock?
> It seems this patch is redundant.
>

Ungates the HDMI-generated TVD, that's it.

Regards,
Angelo

> Regards,
> CK
>
>>
>>>
>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.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
>>>
>>
>