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

From: CK Hu <ck.hu@mediatek.com>
To: Rex-BC Chen <rex-bc.chen@mediatek.com>, <chunkuang.hu@kernel.org>,
	<p.zabel@pengutronix.de>, <daniel@ffwll.ch>, <robh+dt@kernel.org>,
	<krzysztof.kozlowski+dt@linaro.org>, <matthias.bgg@gmail.com>,
	<airlied@linux.ie>
Cc: devicetree@vger.kernel.org, granquet@baylibre.com,
	jitao.shi@mediatek.com, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, msp@baylibre.com,
	Project_Global_Chrome_Upstream_Group@mediatek.com,
	linux-mediatek@lists.infradead.org, wenst@chromium.org,
	linux-arm-kernel@lists.infradead.org,
	angelogioacchino.delregno@collabora.com
Subject: Re: [PATCH v12 11/14] drm/mediatek: dpi: Add tvd_clk enable/disable flow
Date: Tue, 21 Jun 2022 12:08:11 +0800	[thread overview]
Message-ID: <e8ec7c5f8a750a1748b482b040c6efafc1149401.camel@mediatek.com> (raw)
In-Reply-To: <4a873de158868368818c00fbfee1a03f620ad8c9.camel@mediatek.com>

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

> 
> 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;
> > > > 
> > > > 
> > > 
> > > 
> > 
> > 
> 
> 