Re: [PATCH v5 09/20] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers

From: Linus Walleij <linus.walleij@linaro.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Sam Ravnborg <sam@ravnborg.org>, Wolfram Sang <wsa@kernel.org>,
	MSM <linux-arm-msm@vger.kernel.org>,
	Rob Clark <robdclark@chromium.org>,
	Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>,
	Stephen Boyd <swboyd@chromium.org>,
	Steev Klimaszewski <steev@kali.org>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	linux-i2c <linux-i2c@vger.kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	"open list:DRM PANEL DRIVERS" <dri-devel@lists.freedesktop.org>,
	Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
	Robert Foss <robert.foss@linaro.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 09/20] drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers
Date: Sat, 1 May 2021 13:59:06 +0200	[thread overview]
Message-ID: <CACRpkdbZxauBFLvR_MMx4WD+K6DftK19Fivt_mkE=+Xr2EPUvQ@mail.gmail.com> (raw)
In-Reply-To: <20210423095743.v5.9.I3e68fa38c4ccbdbdf145cad2b01e83a1e5eac302@changeid>

On Fri, Apr 23, 2021 at 6:59 PM Douglas Anderson <dianders@chromium.org> wrote:

> Let's use the newly minted aux bus to break up the driver into sub
> drivers. We're not doing a full breakup here: all the code is still in
> the same file and remains largely untouched. The big goal here of
> using sub-drivers is to allow part of our code to finish probing even
> if some other code needs to defer. This can solve some chicken-and-egg
> problems. Specifically:
> - In commit 48834e6084f1 ("drm/panel-simple: Support hpd-gpios for
>   delaying prepare()") we had to add a bit of a hack to simpel-panel
>   to support HPD showing up late. We can get rid of that hack now
>   since the GPIO part of our driver can finish probing early.
> - We have a desire to expose our DDC bus to simple-panel (and perhaps
>   to a backlight driver?). That will end up with the same
>   chicken-and-egg problem. A future patch to move this to a sub-driver
>   will fix it.
> - If/when we support the PWM functionality present in the bridge chip
>   for a backlight we'll end up with another chicken-and-egg
>   problem. If we allow the PWM to be a sub-driver too then it solves
>   this problem.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>
> Changes in v5:
> - Fix module compile problems (Bjorn + kbuild bot)
> - Remove useless MODULE_DEVICE_TABLE (Bjorn).

This is generally a good idea. I have no idea when to use
auxbus or MFD but I trust that you researched that so:
Acked-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij