From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Stephen Boyd <swboyd@chromium.org>
Cc: Sam Ravnborg <sam@ravnborg.org>,
Andrzej Hajda <a.hajda@samsung.com>,
Neil Armstrong <narmstrong@baylibre.com>,
Jernej Skrabec <jernej.skrabec@siol.net>,
Jonas Karlman <jonas@kwiboo.se>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
Douglas Anderson <dianders@chromium.org>,
Sean Paul <seanpaul@chromium.org>
Subject: Re: [PATCH v2 0/4] drm/bridge: ti-sn65dsi86: Support EDID reading
Date: Tue, 23 Mar 2021 02:00:23 +0200 [thread overview]
Message-ID: <YFkvl9tzP5Nj54C4@pendragon.ideasonboard.com> (raw)
In-Reply-To: <160436612483.884498.883110130131457033@swboyd.mtv.corp.google.com>
Hi Stephen,
On Mon, Nov 02, 2020 at 05:15:24PM -0800, Stephen Boyd wrote:
> Quoting Sam Ravnborg (2020-11-01 09:37:41)
> > Hi Stephen.
> >
> > On Thu, Oct 29, 2020 at 06:17:34PM -0700, Stephen Boyd wrote:
> > > This patch series cleans up the DDC code a little bit so that
> > > it is more efficient time wise and supports grabbing the EDID
> > > of the eDP panel over the aux channel. I timed this on a board
> > > I have on my desk and it takes about 20ms to grab the EDID out
> > > of the panel and make sure it is valid.
> > >
> > > The first two patches seem less controversial so I stuck them at
> > > the beginning. The third patch does the EDID reading and caches
> > > it so we don't have to keep grabbing it over and over again. And
> > > finally the last patch updates the reply field so that short
> > > reads and nacks over the channel are reflected properly instead of
> > > treating them as some sort of error that can't be discerned.
> > >
> > > Stephen Boyd (4):
> > > drm/bridge: ti-sn65dsi86: Combine register accesses in
> > > ti_sn_aux_transfer()
> > > drm/bridge: ti-sn65dsi86: Make polling a busy loop
> > > drm/bridge: ti-sn65dsi86: Read EDID blob over DDC
> > > drm/bridge: ti-sn65dsi86: Update reply on aux failures
> >
> > Series looks good. You can add my a-b on the full series.
> > Acked-by: Sam Ravnborg <sam@ravnborg.org>
> >
> > I can apply after Douglas have had a look at the patches he did not r-b
> > yet.
> >
> > Any chance we can convince you to prepare this bridge driver for use in
> > a chained bridge setup where the connector is created by the display
> > driver and uses drm_bridge_funcs?
> >
> > First step wuld be to introduce the use of a panel_bridge.
> > Then add get_edid to drm_bridge_funcs and maybe more helpers.
> >
> > Then natural final step would be to move connector creation to the
> > display driver - see how other uses drm_bridge_connector_init() to do so
> > - it is relatively simple.
> >
> > Should be doable - and reach out if you need some help.
>
> I started to look at this and got stuck at ti_sn_bridge_get_bpp(). Where
> can I get the details of the bpc for the downstream bridge or panel? Is
> there some function that can tell this bridge what the bpc is for the
> attached connector?
I've posted a patch series to convert to DRM_BRIDGE_ATTACH_NO_CONNECTOR
yesterday (and have CC'ed you), but I've overlooked this particular
problem :-S
You can't get the connector in the .enable() operation, but you can get
it in .atomic_enable(), with
drm_atomic_get_new_connector_for_encoder(). This being said, it's
probably not the right option.
What matters here isn't the bpc for the connector, but the format
expected by the next bridge in the chain. drm_bridge_funcs has two
operations, .atomic_get_output_bus_fmts() and
.atomic_get_input_bus_fmts(), to negotiate that format along a chain of
bridges. The panel bridge driver (drivers/gpu/drm/bridge/panel.c)
doesn't implement those operations, and neither does
display-connector.c, so that may be what we should start with.
> I see that td_mode_valid() in
> drivers/gpu/drm/bridge/tc358775.c stores away the bpc from the incoming
> drm_display_info pointer but I'm not sure that is correct because can't
> that be called for various and not necessarily the one we're using?
You're right, .mode_valid() shouldn't do that.
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2021-03-23 0:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-30 1:17 [PATCH v2 0/4] drm/bridge: ti-sn65dsi86: Support EDID reading Stephen Boyd
2020-10-30 1:17 ` [PATCH v2 1/4] drm/bridge: ti-sn65dsi86: Combine register accesses in ti_sn_aux_transfer() Stephen Boyd
2020-11-02 16:18 ` Doug Anderson
2020-11-02 17:06 ` Stephen Boyd
2020-10-30 1:17 ` [PATCH v2 2/4] drm/bridge: ti-sn65dsi86: Make polling a busy loop Stephen Boyd
2020-10-30 1:17 ` [PATCH v2 3/4] drm/bridge: ti-sn65dsi86: Read EDID blob over DDC Stephen Boyd
2020-11-01 19:20 ` Laurent Pinchart
2020-11-02 16:06 ` Doug Anderson
2020-11-02 17:38 ` Stephen Boyd
2020-11-02 21:55 ` Laurent Pinchart
2020-10-30 1:17 ` [PATCH v2 4/4] drm/bridge: ti-sn65dsi86: Update reply on aux failures Stephen Boyd
2020-11-02 16:30 ` Doug Anderson
2020-11-01 17:37 ` [PATCH v2 0/4] drm/bridge: ti-sn65dsi86: Support EDID reading Sam Ravnborg
2020-11-02 16:37 ` Doug Anderson
2020-11-02 17:09 ` Stephen Boyd
2020-11-03 6:11 ` Vinod Koul
2020-11-03 1:15 ` Stephen Boyd
2020-11-03 2:38 ` Stephen Boyd
2021-03-23 0:00 ` Laurent Pinchart [this message]
2021-03-23 7:25 ` Stephen Boyd
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