Date: Thu, 2 May 2024 18:05:59 +0200
From: neil.armstrong@...aro.org
To: Doug Anderson <dianders@...omium.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

On 02/05/2024 16:27, Doug Anderson wrote:
> 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. ;-)

Yes you assume right

> 
> 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. :-)

Yes let's wait 2 weeks and apply them

Neil

> 
> [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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