linux-kernel - Re: [PATCH v1 0/3] Add support for next gen eDP driver on SnapDragon

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Message-ID: <20210511045550.GL2484@yoga>
Date:   Mon, 10 May 2021 23:55:50 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     sbillaka@...eaurora.org
Cc:     Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <dri-devel@...ts.freedesktop.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>,
        Sean Paul <seanpaul@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Kalyan Thota <kalyan_t@...eaurora.org>,
        Abhinav Kumar <abhinavk@...eaurora.org>,
        Douglas Anderson <dianders@...omium.org>,
        Kuogee Hsieh <khsieh@...eaurora.org>,
        Krishna Manikandan <mkrishn@...eaurora.org>
Subject: Re: [PATCH v1 0/3] Add support for next gen eDP driver on SnapDragon

On Mon 10 May 07:16 CDT 2021, sbillaka@...eaurora.org wrote:

> On 2021-05-06 20:32, Rob Clark wrote:
> > On Wed, May 5, 2021 at 11:47 PM <sbillaka@...eaurora.org> wrote:
> > > 
> > > On 2021-05-05 15:31, Dmitry Baryshkov wrote:
> > > > Hi,
> > > >
> > > > On Wed, 5 May 2021 at 11:17, Sankeerth Billakanti
> > > > <sbillaka@...eaurora.org> wrote:
> > > >>
> > > >> These patches add support for the next generation eDP driver on
> > > >> SnapDragon
> > > >> with dpu support. The existing eDP driver cannot support the new eDP
> > > >> hardware. So, to maintain backward compatibility, the older eDP driver
> > > >> is
> > > >> moved to v200 folder and the new generation eDP driver is added in
> > > >> the v510 folder.
> > > >
> > > > What exactly does this version correspond to?
> > > > I assume that v510 corresponds to sdmshrike/sc8180x. Is it right?
> > > [Sankeerth] This is for sc7280.
> > > 
> > > > Is it really so specific, or just v2/v5 would be enough? Not to
> > > > mention that this is the MDP/ version, while other blocks tend to use
> > > > block-specific versions/ids.
> > > [Sankeerth] I can rename it as edp-v1 and edp-v2. Edp v1 is very old
> > > chip and there is considerable HW delta between v1 and v2. So, we want
> > > to separate the driver. We followed similar model for DPU driver
> > > where,
> > > MDP4, MDP5 and DPU have separate folders. EDP v1 belongs to MDP4
> > > generation.
> > 
> > Bjorn brought up the idea of just dropping the existing drm/msm/edp..
> > since the efforts to upstream the platform it worked on (8084?)
> > fizzled out, I don't think there is any device which uses it.
> > 
> > But it does sound like edp is a subset of the the newer dp driver, so
> > seems sort of like the better approach would be to add edp support to
> > dp.  I believe Bjorn has something based on this approach which is
> > working for sc8280 (although not sure if it is in shape to post
> > patches yet)
> > 
> > BR,
> > -R
> Hi Rob,
> I will explore to integrate native eDP driver as part of DP driver. Will
> follow up with new patchsets.
> 
> Hi Dmitry,
> I will move the eDP phy to qmp drivers folder in the new patchsets so that
> it can reuse the dp core driver.
> 

Hi Sankeerth,

I've been working on eDP support for sc8180x recently, which afaict is
identical to sc7280 in this regard. I finally got the patches cleaned up
and posted here:
https://lore.kernel.org/linux-arm-msm/20210511042043.592802-1-bjorn.andersson@linaro.org/T/#t
https://lore.kernel.org/linux-arm-msm/20210511041930.592483-1-bjorn.andersson@linaro.org/T/#t

My initial patches added widebus support, rather than disabling it. But
those patches needs a little bit more polishing - and I finally figured
was able to disable the feature. So I will get back to this.

There's currently a few seconds delay on plug detection, so this needs
to be investigated further and I haven't looked at backlight handling
yet.

Regards,
Bjorn