linux-kernel - Re: [RFC v2 2/5] drm/mediatke: add support for Mediatek SoC MT2701

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Date:	Fri, 27 May 2016 15:29:00 +0800
From:	YT Shen <yt.shen@...iatek.com>
To:	CK Hu <ck.hu@...iatek.com>
CC:	<dri-devel@...ts.freedesktop.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	"Mark Rutland" <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"Russell King" <linux@....linux.org.uk>,
	David Airlie <airlied@...ux.ie>,
	"Matthias Brugger" <matthias.bgg@...il.com>,
	Mao Huang <littlecvr@...omium.org>,
	"Bibby Hsieh" <bibby.hsieh@...iatek.com>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>,
	<srv_heupstream@...iatek.com>,
	"Sascha Hauer" <kernel@...gutronix.de>,
	<yingjoe.chen@...iatek.com>, <emil.l.velikov@...il.com>
Subject: Re: [RFC v2 2/5] drm/mediatke: add support for Mediatek SoC MT2701

Hi CK,


On Mon, 2016-05-23 at 17:09 +0800, CK Hu wrote:
> Hi, YT:
> 
> Some comments below.
> 
> On Fri, 2016-05-20 at 23:05 +0800, yt.shen@...iatek.com wrote:
> > From: YT Shen <yt.shen@...iatek.com>
> > 
> > This patch add support for the Mediatek MT2701 DISP subsystem.
> > There is only one OVL engine in MT2701.
> > 
> > Signed-off-by: YT Shen <yt.shen@...iatek.com>
> >  
> > +static void mtk_ddp_mux_sel(void __iomem *config_regs,
> > +			    enum mtk_ddp_comp_id cur, enum mtk_ddp_comp_id next)
> > +{
> > +	if (cur == DDP_COMPONENT_BLS && next == DDP_COMPONENT_DSI0) {
> > +		writel_relaxed(BLS_TO_DSI_RDMA1_TO_DPI1,
> > +			       config_regs + DISP_REG_CONFIG_OUT_SEL);
> > +	}
> > +}
> > +
> 
> The function name 'mux' looks strange. The register written here
> controls the single output selection. I prefer to rename it as
> mtk_ddp_sout_sel().
OK, I will rename this function in the next version.
> 
> >  
> > -static const enum mtk_ddp_comp_id mtk_ddp_main[] = {
> > +static const enum mtk_ddp_comp_id mtk_ddp_main_2701[] = {
> > +	DDP_COMPONENT_OVL0,
> > +	DDP_COMPONENT_RDMA0,
> > +	DDP_COMPONENT_COLOR0,
> > +	DDP_COMPONENT_BLS,
> > +	DDP_COMPONENT_DSI0,
> > +};
> > +
> > +static const enum mtk_ddp_comp_id mtk_ddp_ext_2701[] = {
> > +	DDP_COMPONENT_OVL0,
> > +	DDP_COMPONENT_DSI0,
> > +};
> > +
> 
> These two pipelines has the same component such as OVL0 and DSI0. I
> think user program could not enable both crtc at the same time. Maybe
> MT2701 has only one crtc, so you should modify initial flow to create
> only one crtc for main display. Or it's typo for external display pipe,
> please correct it.
MT2701 hardware can support two output concurrently, but we haven't
implement DPI path yet.  We will change it like this:
static const enum mtk_ddp_comp_id mtk_ddp_ext_2701[] = {
	DDP_COMPONENT_RDMA1,
	DDP_COMPONENT_DPI0,
};

Thanks.
yt.shen
> 
> 
> Regards,
> CK
>