Date: Thu, 2 May 2024 07:27:59 -0700
From: Doug Anderson <dianders@...omium.org>
To: neil.armstrong@...aro.org
Cc: dri-devel@...ts.freedesktop.org, Linus Walleij <linus.walleij@...aro.org>, 
	Jani Nikula <jani.nikula@...ux.intel.com>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
	Cong Yang <yangcong5@...qin.corp-partner.google.com>, Hsin-Yi Wang <hsinyi@...gle.com>, 
	Brian Norris <briannorris@...omium.org>, Sam Ravnborg <sam@...nborg.org>, 
	Javier Martinez Canillas <javierm@...hat.com>, Joel Selvaraj <jo@...amily.in>, 
	lvzhaoxiong@...qin.corp-partner.google.com, Daniel Vetter <daniel@...ll.ch>, 
	David Airlie <airlied@...il.com>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Jonathan Corbet <corbet@....net>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, linux-doc@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/9] drm/mipi-dsi: Reduce bloat and add funcs for
 cleaner init seqs

Hi,

On Thu, May 2, 2024 at 12:48 AM Neil Armstrong
<neil.armstrong@...aro.org> wrote:
>
> Hi,
>
> On 01/05/2024 17:41, Douglas Anderson wrote:
> > The consensus of many DRM folks is that we want to move away from DSI
> > drivers defining tables of init commands. Instead, we want to move to
> > init functions that can use common DRM functions. The issue thus far
> > has been that using the macros mipi_dsi_generic_write_seq() and
> > mipi_dsi_dcs_write_seq() bloats the driver using them.
> >
> > While trying to solve bloat, we realized that the majority of the it
> > was easy to solve. This series solves the bloat for existing drivers
> > by moving the printout outside of the macro.
> >
> > During discussion of my v1 patch to fix the bloat [1], we also decided
> > that we really want to change the way that drivers deal with init
> > sequences to make it clearer. In addition to being cleaner, a side
> > effect of moving drivers to the new style reduces bloat _even more_.
> >
> > This series also contains a few minor fixes / cleanups that I found
> > along the way.
> >
> > This series converts four drivers over to the new
> > mipi_dsi_dcs_write_seq_multi() function. Not all conversions have been
> > tested, but hopefully they are straightforward enough. I'd appreciate
> > testing.
> >
> > NOTE: In v3 I tried to incorporate the feedback from v2. I also
> > converted the other two panels I could find that used table-based
> > initialization.
> >
> > [1] https://lore.kernel.org/r/20240424172017.1.Id15fae80582bc74a0d4f1338987fa375738f45b9@changeid
> >
> > Changes in v3:
> > - ("mipi_dsi_*_write functions don't need to ratelimit...") moved earlier.
> > - Add a TODO item for cleaning up the deprecated macros/functions.
> > - Fix spacing of init function.
> > - Inline kerneldoc comments for struct mipi_dsi_multi_context.
> > - Rebased upon patch to remove ratelimit of prints.
> > - Remove an unneeded error print.
> > - Squash boe-tv101wum-nl6 lowercase patch into main patch
> > - Use %zd in print instead of casting errors to int.
> > - drm/panel: ili9882t: Don't use a table for initting panels
> > - drm/panel: innolux-p079zca: Don't use a table for initting panels
> >
> > Changes in v2:
> > - Add some comments to the macros about printing and returning.
> > - Change the way err value is handled in prep for next patch.
> > - Modify commit message now that this is part of a series.
> > - Rebased upon patches to avoid theoretical int overflow.
> > - drm/mipi-dsi: Fix theoretical int overflow in mipi_dsi_dcs_write_seq()
> > - drm/mipi-dsi: Fix theoretical int overflow in mipi_dsi_generic_write_seq()
> > - drm/mipi-dsi: Introduce mipi_dsi_*_write_seq_multi()
> > - drm/mipi-dsi: mipi_dsi_*_write functions don't need to ratelimit prints
> > - drm/panel: boe-tv101wum-nl6: Convert hex to lowercase
> > - drm/panel: boe-tv101wum-nl6: Don't use a table for initting commands
> > - drm/panel: novatek-nt36672e: Switch to mipi_dsi_dcs_write_seq_multi()
> >
> > Douglas Anderson (9):
> >    drm/mipi-dsi: Fix theoretical int overflow in mipi_dsi_dcs_write_seq()
> >    drm/mipi-dsi: Fix theoretical int overflow in
> >      mipi_dsi_generic_write_seq()
> >    drm/mipi-dsi: mipi_dsi_*_write functions don't need to ratelimit
> >      prints
> >    drm/mipi-dsi: Reduce driver bloat of mipi_dsi_*_write_seq()
> >    drm/mipi-dsi: Introduce mipi_dsi_*_write_seq_multi()
> >    drm/panel: novatek-nt36672e: Switch to mipi_dsi_dcs_write_seq_multi()
> >    drm/panel: boe-tv101wum-nl6: Don't use a table for initting panels
> >    drm/panel: ili9882t: Don't use a table for initting panels
> >    drm/panel: innolux-p079zca: Don't use a table for initting panels
>
> Thanks Doug!
>
> I think we all agree on the core changes, now I think we can wait a few weeks
> and try to get some test feedbacks on the indirectly and directly affected
> panels, drm-misc-next won't be merged into linux-next until v6.10-rc1 anyway
> so we have some time to test on our boards.

Great!

Just to be clear, are you suggesting that we leave these patches on
the lists for a few weeks before landing in drm-misc-next, or are you
suggesting that it's safe to land them in drm-misc-next because it
won't make it to linuxnext for a while anyway? I assume the former
(AKA leave it on the lists for a while) but just want to be clear. ;-)

There's nothing terribly urgent about these patches except that they
are blocking Cong Yang's patch series [0] and lvzhaoxiong's patch
series [1]. I think it would be fine for them to send out their patch
series with mine marked as a dependency so we can finish reviewing
their series and then when mine lands theirs will be good to go too.

Maybe we can aim for 2 weeks of stewing on the list if there are no
issues during that time? I know landing in drm-misc during this time
won't help get into mainline faster, but with ChromeOS's "upstream
first" policy it saves us a bunch of headache if we can land things in
our tree from a maintainer tree with stable git hashes (like
drm-misc-next) instead of landing from a mailing list. Certainly that
doesn't mean we want to rush patches in before they're ready, but I
just want to say that there is still some benefit in getting the
patches landed sooner rather than later. :-)

[0] https://lore.kernel.org/r/20240424023010.2099949-1-yangcong5@huaqin.corp-partner.google.com
[1] https://lore.kernel.org/r/20240418081548.12160-3-lvzhaoxiong@huaqin.corp-partner.google.com

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