linux-kernel - Re: [PATCH RFC v2] drm/msm/dpu: Configure DP INTF/PHY selector

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Date: Tue, 25 Jun 2024 23:20:01 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>, 
	Daniel Vetter <daniel@...ll.ch>, Bjorn Andersson <andersson@...nel.org>, linux-arm-msm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2] drm/msm/dpu: Configure DP INTF/PHY selector

On Tue, 25 Jun 2024 at 22:28, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>
>
>
> On 6/25/2024 12:26 PM, Abhinav Kumar wrote:
> >
> >
> > On 6/24/2024 6:39 PM, Abhinav Kumar wrote:
> >>
> >>
> >> On 6/13/2024 4:17 AM, Dmitry Baryshkov wrote:
> >>> From: Bjorn Andersson <andersson@...nel.org>
> >>>
> >>> Some platforms provides a mechanism for configuring the mapping between
> >>> (one or two) DisplayPort intfs and their PHYs.
> >>>
> >>> In particular SC8180X provides this functionality, without a default
> >>> configuration, resulting in no connection between its two external
> >>> DisplayPort controllers and any PHYs.
> >>>
> >>
> >> I have to cross-check internally about what makes it mandatory to
> >> program this only for sc8180xp. We were not programming this so far
> >> for any chipset and this register is present all the way from sm8150
> >> till xe10100 and all the chipsets do not have a correct default value
> >> which makes me think whether this is required to be programmed.
> >>
> >> Will update this thread once I do.
> >>
> >
> > Ok, I checked more. The reason this is mandatory for sc8180xp is the
> > number of controllers is greater than number of PHYs needing this to be
> > programmed. On all other chipsets its a 1:1 mapping.
> >
>
> Correction, number of controllers is < number of PHYs.

Thanks, I'll c&p your explanation to the commit message if you don't mind.

>
> > I am fine with the change once the genmap comment is addressed.

-- 
With best wishes
Dmitry