[Letux-kernel] DSI panels with omapdrm on 4.20-rc

Sebastian Reichel sre at kernel.org
Mon Nov 12 21:09:01 CET 2018


Hi,

On Mon, Nov 12, 2018 at 10:30:21AM -0800, Tony Lindgren wrote:
> * H. Nikolaus Schaller <hns at goldelico.com> [181112 17:35]:
> > 4.20-rc1 seems to have broken our DSI panel driver for the OMAP5 Pyra.

Laurent's patches break omapdrm DSI support in 4.20 (please read as
factual information, not as insult). Note, that there is no working
mainline user of this, so technically its not a user visible
regression.

> > There were some omapdrm API changes which I have tried to fix by inspecting
> > panel-dsi-cm.c and also comparing with panel-tpo-td028ttec1.c (which is still working
> > on our omap3 systems).
> > 
> > I also have removed the tiler patches by Matthijs to make sure that
> > they do not have an influence.
> > 
> > The strange thing is that the panel driver module is not even loaded
> > during probe time, although we have defined the display alias and not
> > changed that compared to 4.19.
> >
> > The other strange thing is that I can manually modprobe the driver
> > and it is loaded and shown by lsmod, but the probe function is never
> > called.
> > 
> > Any hints what we should check and compare and verify?

This is probably fixed by the following patch, which depends on
Laurent's fixes from a few days ago:

https://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-n900.git/commit/?h=droid4-display-omapdrm-4.20-next&id=9aedb0adc243180c08d000d9d9f811da229857c5

> > Did the panel driver compatible matching mechanism change for dsi panels
> > without a bus (dpi panels are usually loaded as an spi bus client)?
> > 
> > Or is there a new CONFIG that must be set?
>
> Test with Laurent's fixes, and also looks like Sebastian also has some
> recent yet to be posted probe order changes on top of Laurent's fixes
> in his linux-n900 branch if Laurent's fixes alone don't help.
> 
> Laurent's patches are "[PATCH v3 0/4] omapdrm: Fix runtime PM issues
> at module load and unload time" and Sebastian's git tree is at
> https://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-n900.git/.
> 
> Adding Laurent and Sebastian to Cc too.

I hope to send a new patchset fixing panel-dsi-cm support in omapdrm
later this week (assuming, that nothing unexpected happens).

-- Sebastian
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