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

Tomi Valkeinen tomi.valkeinen at ti.com
Tue Dec 18 13:05:36 CET 2018

On 18/12/18 13:21, H. Nikolaus Schaller wrote:
> Hi all,
> I am still fighting to get our DSI panel on OMAP5 working again with
> 4.20-rc.
>> Am 20.11.2018 um 10:17 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
>> Hi,
>>> Am 19.11.2018 um 15:18 schrieb Sebastian Reichel <sre at kernel.org>:
>>> Hi,
>>>> So how can I debug the panel->enable()?
>>>> Where should it be called from dss core?
>>>> Then I could check the conditions to call enable().
>>> This is called in omap_encoder_enable(). For debugging I suggest to
>>> add "drm.debug=0xf" kernel argument. "drm/omap: don't check dispc
>>> timings for DSI" fixes a similar problem for panel-dsi-cm.
>> I have checked that and it looks all reasonable and I did enable
>> the same on the 4.19 kernel and they are basically the same (some
>> not obviously significant diffs in sequence or connector numbers).
> We now have added Sebastian's latest patches and found a small bug in
> our panel driver that prevented it from being enabled in v4.20-rc.
> And we also include:
> * drm/omap: Work around missing DISPC in runtime PM handlers

That shouldn't be needed with -rc7.

> Firstly, /sys/kernel/debug/omapdss/clk does not include the DSI1 clocks.
> Therefore
> I can't check if dividers etc. are correct.

It's "dsi1_clks".

> And trying to read dsi1_regs ends in a NULL pointer dereference in
> dsi_runtime_get()
> called from dsi_dump_dsi_regs().

Ok... I guess we have broken the debug facilities.

How's it with the attached patch?


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