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From: Maxime Ripard <maxime@cerno.tech>
To: Robert Foss <robert.foss@linaro.org>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Daniel Vetter <daniel.vetter@intel.com>,
	David Airlie <airlied@linux.ie>, Sam Ravnborg <sam@ravnborg.org>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 04/10] drm/bridge: Document the probe issue with MIPI-DSI bridges
Date: Wed, 28 Jul 2021 15:27:41 +0200	[thread overview]
Message-ID: <20210728132741.dzqqohi34cm56q6j@gilmour> (raw)
In-Reply-To: <YP/P9rJrZyk6zjsT@phenom.ffwll.local>

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Hi,

On Tue, Jul 27, 2021 at 11:20:54AM +0200, Daniel Vetter wrote:
> On Mon, Jul 26, 2021 at 05:16:57PM +0200, Maxime Ripard wrote:
> > Hi Daniel,
> > 
> > On Wed, Jul 21, 2021 at 02:05:01PM +0200, Daniel Vetter wrote:
> > > On Tue, Jul 20, 2021 at 03:45:19PM +0200, Maxime Ripard wrote:
> > > > Interactions between bridges, panels, MIPI-DSI host and the component
> > > > framework are not trivial and can lead to probing issues when
> > > > implementing a display driver. Let's document the various cases we need
> > > > too consider, and the solution to support all the cases.
> > > > 
> > > > Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> > > 
> > > I still have this dream that eventually we resurrect a patch to add
> > > device_link to bridges/panels (ideally automatically), to help with some
> > > of the suspend/resume issues around here.
> > > 
> > > Will this make things worse?
> > > 
> > > I think it'd be really good to figure that out with some coding, since if
> > > we have incompatible solution to handle probe issues vs suspend/resume
> > > issues, we're screwed.
> > > 
> > > Atm the duct-tape is to carefully move things around between suspend and
> > > suspend_early hooks (and resume and resume_late) and hope it all works ...
> > 
> > My initial idea to fix this was indeed to use device links. I gave up
> > after a while since it doesn't look like there's a way to add a device
> > link before either the bridge or encoder probes.
> > 
> > Indeed the OF-Graph representation is device-specific, so it can't be
> > generic, and if you need to probe to add that link, well, it's already
> > too late for the probe ordering :)
> 
> But don't we still need the device_link for suspend/resume and module
> reload? All very annoying indeed anyway.

I guess we would still need it for proper suspend and resume ordering
(but I never really worked on that part, so I'm not sure), but it's a
bit orthogonal to the issue here since those can be added after probe

Maxime

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  reply	other threads:[~2021-07-28 13:27 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-20 13:45 [PATCH 00/10] drm/bridge: Make panel and bridge probe order consistent Maxime Ripard
2021-07-20 13:45 ` [PATCH 01/10] Revert "drm/vc4: dsi: Only register our component once a DSI device is attached" Maxime Ripard
2021-07-20 13:45 ` [PATCH 02/10] drm/bridge: Add a function to abstract away panels Maxime Ripard
2021-07-22  7:49   ` Jagan Teki
2021-07-20 13:45 ` [PATCH 03/10] drm/bridge: Add documentation sections Maxime Ripard
2021-07-20 13:45 ` [PATCH 04/10] drm/bridge: Document the probe issue with MIPI-DSI bridges Maxime Ripard
2021-07-21 12:05   ` Daniel Vetter
2021-07-21 12:06     ` Daniel Vetter
2021-07-26 15:16     ` Maxime Ripard
2021-07-27  9:20       ` Daniel Vetter
2021-07-28 13:27         ` Maxime Ripard [this message]
2021-07-27  9:42   ` Jagan Teki
2021-07-28 13:35     ` Maxime Ripard
2021-08-05 12:19       ` Jagan Teki
2021-07-20 13:45 ` [PATCH 05/10] drm/panel: Create attach and detach callbacks Maxime Ripard
2021-07-22  7:53   ` Jagan Teki
2021-07-20 13:45 ` [PATCH 06/10] drm/bridge: panel: Call attach and detach for the panel Maxime Ripard
2021-07-20 13:45 ` [PATCH 07/10] drm/vc4: dsi: Switch to drm_of_get_next Maxime Ripard
2021-07-20 13:45 ` [PATCH 08/10] drm/panel: raspberrypi-touchscreen: Prevent double-free Maxime Ripard
     [not found]   ` <YPcFrKLq1dhTcOUL@ravnborg.org>
2021-07-22  9:38     ` Maxime Ripard
2021-07-20 13:45 ` [PATCH 09/10] drm/panel: raspberrypi-touchscreen: Use the attach hook Maxime Ripard
2021-07-20 13:45 ` [PATCH 10/10] drm/panel: raspberrypi-touchscreen: Remove MIPI-DSI driver Maxime Ripard

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