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 <s...@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
