From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Dave Stevenson <dave.stevenson@raspberrypi.com>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
DRI Development <dri-devel@lists.freedesktop.org>
Cc: Marek Vasut <marex@denx.de>,
Jagan Teki <jagan@amarulasolutions.com>,
Neil Armstrong <narmstrong@baylibre.com>,
Jonas Karlman <jonas@kwiboo.se>,
Douglas Anderson <dianders@chromium.org>,
Jernej Skrabec <jernej.skrabec@gmail.com>,
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
Robert Foss <robert.foss@linaro.org>,
Andrzej Hajda <andrzej.hajda@intel.com>,
Andrzej Hajda <andrzej.hajda@gmail.com>,
Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH V2 0/3] DSI host and peripheral initialisation ordering
Date: Wed, 11 May 2022 16:58:21 +0200 [thread overview]
Message-ID: <e96197f9-948a-997e-5453-9f9d179b5f5a@samsung.com> (raw)
In-Reply-To: <CAPY8ntAi1tM7BZEpKkMAasRH3R_+tJCUFY7k-yVBdtogvxQNRA@mail.gmail.com>
Hi Dave,
On 05.04.2022 13:43, Dave Stevenson wrote:
> On Fri, 18 Mar 2022 at 12:25, Dave Stevenson
> <dave.stevenson@raspberrypi.com> wrote:
>> On Fri, 4 Mar 2022 at 15:18, Dave Stevenson
>> <dave.stevenson@raspberrypi.com> wrote:
>>> Hi All
>> A gentle ping on this series. Any comments on the approach?
>> Thanks.
> I realise the merge window has just closed and therefore folks have
> been busy, but no responses on this after a month?
>
> Do I give up and submit a patch to document that DSI is broken and no one cares?
Thanks for pointing this patchset in the 'drm: bridge: Add Samsung MIPI
DSIM bridge' thread, otherwise I would miss it since I'm not involved
much in the DRM development.
This resolves most of the issues in the Exynos DSI and its recent
conversion to the drm bridge framework. I've added the needed
prepare_upstream_first flags to the panels and everything works fine
without the bridge chain order hacks.
Feel free to add:
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
The only remaining thing to resolve is the moment of enabling DSI host.
The proper sequence is:
1. host power on, 2. device power on, 3. host init, 4. device init, 5.
video enable.
#1 is done in dsi's pre_enable, #2 is done in panel's prepare. #3 was so
far done in the first host transfer call, which usually happens in
panel's prepare, then the #4 happens. Then video enable is done in the
enable callbacks.
Jagan wants to move it to the dsi host pre_enable() to let it work with
DSI bridges controlled over different interfaces
(https://lore.kernel.org/all/20220504114021.33265-6-jagan@amarulasolutions.com/
). This however fails on Exynos with DSI panels, because when dsi's
pre_enable is called, the dsi device is not yet powered. I've discussed
this with Andrzej Hajda and we came to the conclusion that this can be
resolved by adding the init() callback to the struct mipi_dsi_host_ops.
Then DSI client (next bridge or panel) would call it after powering self
on, but before sending any DSI commands in its pre_enable/prepare functions.
I've prepared a prototype of such solution. This approach finally
resolved all the initialization issues! The bridge chain finally matches
the hardware, no hack are needed, and everything is controlled by the
DRM core. This prototype also includes the Jagan's patches, which add
IMX support to Samsung DSIM. If one is interested, here is my git repo
with all the PoC patches:
https://github.com/mszyprow/linux/tree/v5.18-next-20220511-dsi-rework
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
next prev parent reply other threads:[~2022-05-11 14:58 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-04 15:17 [PATCH V2 0/3] DSI host and peripheral initialisation ordering Dave Stevenson
2022-03-04 15:17 ` [PATCH V2 1/4] drm/bridge: Remove duplication from drm_bridge and drm_atomic_bridge chains Dave Stevenson
2022-06-08 11:00 ` Dmitry Baryshkov
2022-07-18 18:16 ` Sam Ravnborg
2022-03-04 15:17 ` [PATCH V2 2/4] drm/bridge: Introduce pre_enable_upstream_first to alter bridge init order Dave Stevenson
2022-09-14 9:46 ` Jagan Teki
2022-03-04 15:17 ` [PATCH V2 3/4] drm/panel: Add prepare_upstream_first flag to drm_panel Dave Stevenson
2022-06-08 11:02 ` Dmitry Baryshkov
2022-10-06 14:25 ` Jagan Teki
2022-10-07 12:55 ` Dave Stevenson
2022-10-17 2:44 ` Jagan Teki
2022-10-18 17:10 ` Dave Stevenson
2022-03-04 15:17 ` [PATCH V2 4/4] drm/bridge: Document the expected behaviour of DSI host controllers Dave Stevenson
2022-03-18 12:25 ` [PATCH V2 0/3] DSI host and peripheral initialisation ordering Dave Stevenson
2022-04-05 11:43 ` Dave Stevenson
2022-05-11 14:58 ` Marek Szyprowski [this message]
2022-05-11 15:47 ` Marek Vasut
2022-05-11 17:29 ` Marek Szyprowski
2022-05-13 14:01 ` Jagan Teki
2022-05-11 15:47 ` Dave Stevenson
2022-05-18 14:05 ` Marek Szyprowski
2022-05-18 22:53 ` Andrzej Hajda
2022-05-19 12:56 ` Dave Stevenson
2022-06-08 10:49 ` Dave Stevenson
2022-06-08 10:57 ` Jagan Teki
2022-06-07 19:46 ` Jagan Teki
2022-05-13 13:57 ` Jagan Teki
2022-06-10 7:52 ` Lucas Stach
2022-07-06 7:09 ` Frieder Schrempf
2022-07-06 7:13 ` Jagan Teki
2022-07-06 10:27 ` Dave Stevenson
2022-07-06 10:43 ` Frieder Schrempf
2022-07-19 14:36 ` Dave Stevenson
2022-07-18 20:52 ` Sam Ravnborg
2022-07-19 13:45 ` Dave Stevenson
2022-11-13 13:06 ` Dmitry Baryshkov
2022-11-15 14:14 ` Dave Stevenson
2022-11-15 14:21 ` Dmitry Baryshkov
2022-11-15 14:38 ` Dave Stevenson
2022-11-17 13:24 ` Dmitry Baryshkov
2022-11-17 14:34 ` Maxime Ripard
2022-11-17 14:35 ` Dmitry Baryshkov
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