Re: [PATCH v12 11/14] drm/mediatek: dpi: Add tvd_clk enable/disable flow

[Rex-BC Chen <rex-bc.chen@mediatek.com>]

On Tue, 2022-06-21 at 13:54 +0800, CK Hu wrote:
> Hi, Rex:
> 
> On Tue, 2022-06-21 at 13:47 +0800, Rex-BC Chen wrote:
> > On Tue, 2022-06-21 at 12:08 +0800, CK Hu wrote:
> > > Hi, Rex:
> > > 
> > > On Tue, 2022-06-21 at 11:50 +0800, Rex-BC Chen wrote:
> > > > On Tue, 2022-06-21 at 11:45 +0800, CK Hu wrote:
> > > > > On Tue, 2022-06-21 at 11:11 +0800, Rex-BC Chen wrote:
> > > > > > On Tue, 2022-06-21 at 10:55 +0800, CK Hu wrote:
> > > > > > > Hi, Bo-Chen:
> > > > > > > 
> > > > > > > On Mon, 2022-06-20 at 20:10 +0800, Bo-Chen Chen wrote:
> > > > > > > > We should enable/disable tvd_clk when
> > > > > > > > power_on/power_off,
> > > > > > > > so
> > > > > > > > add
> > > > > > > > this
> > > > > > > > patch to do this.
> > > > > > > 
> > > > > > > Without this patch, what would happen?
> > > > > > > It seems this patch is redundant for these SoCs:
> > > > > > > 
> > > > > > > static const struct of_device_id mtk_dpi_of_ids[] = {
> > > > > > > 	{ .compatible = "mediatek,mt2701-dpi",
> > > > > > > 	  .data = &mt2701_conf,
> > > > > > > 	},
> > > > > > > 	{ .compatible = "mediatek,mt8173-dpi",
> > > > > > > 	  .data = &mt8173_conf,
> > > > > > > 	},
> > > > > > > 	{ .compatible = "mediatek,mt8183-dpi",
> > > > > > > 	  .data = &mt8183_conf,
> > > > > > > 	},
> > > > > > > 	{ .compatible = "mediatek,mt8192-dpi",
> > > > > > > 	  .data = &mt8192_conf,
> > > > > > > 	},
> > > > > > > 	{ },
> > > > > > > };
> > > > > > > 
> > > > > > > Regards,
> > > > > > > CK
> > > > > > > 
> > > > > > 
> > > > > > Hello CK,
> > > > > > 
> > > > > > IMO, this is a bug fix patch. From the usage of clock, if
> > > > > > we
> > > > > > want
> > > > > > to
> > > > > > use it, we should enable it . Therefore, I think we should
> > > > > > add
> > > > > > this
> > > > > > and
> > > > > > I will add a fix tag for this patch.
> > > > > 
> > > > > I think mt8173 chromebook use this driver for HDMI output. So
> > > > > mt8173
> > > > > chromebook HDMI could not work normally?
> > > > > 
> > > > > Regards,
> > > > > CK
> > > > > 
> > > > 
> > > > Hmm..
> > > > I am not sure about this. But without this patch, dpi is also
> > > > working
> > > > in mt8183/mt8192. It may be related to the ccf driver. But
> > > > anyway,
> > > > I
> > > > think we should do this whether ccf driver helps us to enable
> > > > this
> > > > clock.
> > > 
> > > OK. So, could you help to fix the bug in ccf? If HDMI is disabled
> > > but
> > > ccf still turn on this clock, the power would be wasted.
> > > 
> > > Regards,
> > > CK
> > > 
> > 
> > I am also testing if we don't have this patch and it also "works"
> > (dpintf is working fine).
> > do you think we need this patch or just drop this?
> > 
> > For the ccf driver, I am not familiar to ccf and also not a expert
> > of
> > ccf.
> > It just a guest for this. I am not sure whether it's a "bug" or
> > just
> > a.
> > And I think it's not the purpose of this series. If there is any
> > issue,
> > I think we will fix it in the future.
> 
> Because we have no idea how this works, I think it's better to drop
> this patch.
> 
> Regards,
> CK
> 

ok, I will drop this patch in next version.

BRs,
Bo-Chen

> > 
> > BRs,
> > Bo-Chen
> > 
> > > > 
> > > > BRs,
> > > > Bo-Chen
> > > > 
> > > > > > 
> > > > > > BRs,
> > > > > > Bo-Chen
> > > > > > > 
> > > > > > > > 
> > > > > > > > Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
> > > > > > > > ---
> > > > > > > >  drivers/gpu/drm/mediatek/mtk_dpi.c | 11 ++++++++++-
> > > > > > > >  1 file changed, 10 insertions(+), 1 deletion(-)
> > > > > > > > 
> > > > > > > > diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > > > > > > b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > > > > > > index 2717b1741b7a..f83ecb154457 100644
> > > > > > > > --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > > > > > > +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > > > > > > @@ -455,6 +455,7 @@ static void
> > > > > > > > mtk_dpi_power_off(struct
> > > > > > > > mtk_dpi
> > > > > > > > *dpi)
> > > > > > > >  	mtk_dpi_disable(dpi);
> > > > > > > >  	clk_disable_unprepare(dpi->pixel_clk);
> > > > > > > >  	clk_disable_unprepare(dpi->engine_clk);
> > > > > > > > +	clk_disable_unprepare(dpi->tvd_clk);
> > > > > > > >  }
> > > > > > > >  
> > > > > > > >  static int mtk_dpi_power_on(struct mtk_dpi *dpi)
> > > > > > > > @@ -464,10 +465,16 @@ static int
> > > > > > > > mtk_dpi_power_on(struct
> > > > > > > > mtk_dpi
> > > > > > > > *dpi)
> > > > > > > >  	if (++dpi->refcount != 1)
> > > > > > > >  		return 0;
> > > > > > > >  
> > > > > > > > +	ret = clk_prepare_enable(dpi->tvd_clk);
> > > > > > > > +	if (ret) {
> > > > > > > > +		dev_err(dpi->dev, "Failed to enable tvd
> > > > > > > > pll:
> > > > > > > > %d\n",
> > > > > > > > ret);
> > > > > > > > +		goto err_refcount;
> > > > > > > > +	}
> > > > > > > > +
> > > > > > > >  	ret = clk_prepare_enable(dpi->engine_clk);
> > > > > > > >  	if (ret) {
> > > > > > > >  		dev_err(dpi->dev, "Failed to enable
> > > > > > > > engine
> > > > > > > > clock:
> > > > > > > > %d\n", ret);
> > > > > > > > -		goto err_refcount;
> > > > > > > > +		goto err_engine;
> > > > > > > >  	}
> > > > > > > >  
> > > > > > > >  	ret = clk_prepare_enable(dpi->pixel_clk);
> > > > > > > > @@ -484,6 +491,8 @@ static int mtk_dpi_power_on(struct
> > > > > > > > mtk_dpi
> > > > > > > > *dpi)
> > > > > > > >  
> > > > > > > >  err_pixel:
> > > > > > > >  	clk_disable_unprepare(dpi->engine_clk);
> > > > > > > > +err_engine:
> > > > > > > > +	clk_disable_unprepare(dpi->tvd_clk);
> > > > > > > >  err_refcount:
> > > > > > > >  	dpi->refcount--;
> > > > > > > >  	return ret;
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