linux-kernel - Re: [PATCH] drm/panel: himax-hx83112a: transition to mipi

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Message-ID: <ZuI2rrEzYCK9yDU7@embed-PC.myguest.virtualbox.org>
Date: Thu, 12 Sep 2024 06:02:46 +0530
From: Abhishek Tamboli <abhishektamboli9@...il.com>
To: neil.armstrong@...aro.org
Cc: dianders@...omium.org, tejasvipin76@...il.com,
	quic_jesszhan@...cinc.com, maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com,
	daniel@...ll.ch, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, javierm@...hat.com
Subject: Re: [PATCH] drm/panel: himax-hx83112a: transition to mipi_dsi
 wrapped functions

On Wed, Sep 11, 2024 at 09:41:30AM +0200, neil.armstrong@...aro.org wrote:
> On 10/09/2024 23:19, Doug Anderson wrote:
> > Hi,
> > 
> > On Sat, Sep 7, 2024 at 1:32 AM Tejas Vipin <tejasvipin76@...il.com> wrote:
> > > 
> > > On 9/7/24 3:53 AM, Jessica Zhang wrote:
> > > > 
> > > > 
> > > > On 9/6/2024 3:14 PM, Jessica Zhang wrote:
> > > > > 
> > > > > 
> > > > > On 9/4/2024 7:15 AM, Tejas Vipin wrote:
> > > > > > Changes the himax-hx83112a panel to use multi style functions for
> > > > > > improved error handling.
> > > > > > 
> > > > > > Signed-off-by: Tejas Vipin <tejasvipin76@...il.com>
> > > > > 
> > > > > Reviewed-by: Jessica Zhang <quic_jesszhan@...cinc.com>
> > > > 
> > > > Hi Tejas,
> > > > 
> > > > Just a heads up, it seems that this might be a duplicate of this change [1]?
> > > > 
> > > > Thanks,
> > > > 
> > > > Jessica Zhang
> > > > 
> > > > [1] https://patchwork.freedesktop.org/patch/612367/?series=138155&rev=1
> > > 
> > > Ah, thanks for letting me know. I hadn't realized someone else had
> > > started working on this too.
> > > 
> > > However, I would argue that my patch [2] is a better candidate for merging
> > > because of the following reasons:
> > > 
> > > 1) Removes unnecessary error printing:
> > > The mipi_dsi_*_multi() functions all have inbuilt error printing which
> > > makes printing errors after hx83112a_on unnecessary as is addressed in
> > > [2] like so:
> > > 
> > > > -     ret = hx83112a_on(ctx);
> > > > +     ret = hx83112a_on(ctx->dsi);
> > > >        if (ret < 0) {
> > > > -             dev_err(dev, "Failed to initialize panel: %d\n", ret);
> > > >                gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> > > >                regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
> > > > -             return ret;
> > > >        }
> > > 
> > > [2] also removes the unnecessary dev_err after regulator_bulk_enable as was
> > > addressed in [3] like so:
> > > 
> > > >        ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
> > > > -     if (ret < 0) {
> > > > -             dev_err(dev, "Failed to enable regulators: %d\n", ret);
> > > > +     if (ret < 0)
> > > >                return ret;
> > > > -     }
> > > 
> > > 2) Better formatting
> > > 
> > > The mipi_dsi_dcs_write_seq_multi statements in [1] aren't formatted
> > > quite right according to what has been done so far. They are written as
> > > such in [1]:
> > > 
> > > > +     mipi_dsi_dcs_write_seq_multi(&dsi_ctx, HX83112A_SETTP1,
> > > >                               0x02, 0x00, 0xa8, 0x01, 0xa8, 0x0d, 0xa4, 0x0e);
> > > 
> > > Where they should be written as such in [2]:
> > > 
> > > > +     mipi_dsi_dcs_write_seq_multi(&dsi_ctx, HX83112A_SETTP1,
> > > > +                                  0x02, 0x00, 0xa8, 0x01, 0xa8, 0x0d, 0xa4, 0x0e);
> > > 
> > > All in all, the module generated using my patch ends up being a teensy
> > > bit smaller (1% smaller). But if chronology is what is important, then
> > > it would at least be nice to see the above changes as part of Abhishek's
> > > patch too. And I'll be sure to look at the mail in the drm inbox now
> > > onwards :p
> > > 
> > > [1] https://patchwork.freedesktop.org/patch/612367/?series=138155&rev=1
> > > [2] https://lore.kernel.org/all/20240904141521.554451-1-tejasvipin76@gmail.com/
> > > [3] https://lore.kernel.org/all/CAD=FV=XRZKL_ppjUKDK61fQkWhHiQCJLfmVBS7wSo4sUux2g8Q@mail.gmail.com/
> > 
> > I would tend to agree that Tejas's patch looks slightly better, but
> > Abhishek's patch appears to have been posted first.
> > 
> > Neil: any idea what to do here? Maybe a Co-Developed-by or something?
> > ...or we could land Abhishek and Tejas could post a followup for the
> > extra cleanup?
> 
> Yeah usually I take the first one when they are equal, but indeed Tejas
> cleanup up a little further and better aligned the parameters so I think
> Tejas's one is a better looking version.
> 
> In this case we should apply Teja's one, nothing personal Abhishek!
No problem at all, I completely understand. It makes sense to go with 
Tejas's version.

Thanks for letting me know, and I appreciate the feedback!

Regards,
Abhishek