Re: OMAPDSS: omap5 SYNC_LOST error with DPI/LCD

[Vikas Patil <vikasmpatil@xxxxxxxxx>]

Hi Tomi,

>That driver cannot be used with omapdrm, which uses omapdss. There's no TDF19988 driver for omapdss (at least in the mainline),

Just to better understand, could you please explain why I can't use it with omadrm and omapdss? Which scenario this driver will be useful?  I think I still didn't understand how all this sit together.

Do you think following driver can be used as a reference to start?
http://www.spinics.net/lists/linux-omap/msg104598.html (Sil9022 DPI to HDMI Encoder).

Thanks for sparing your valuable time here.

Regards,

Vikash

On Mon, May 12, 2014 at 6:01 PM, Vikas Patil <vikasmpatil@xxxxxxxxx> wrote:

Hi Tomi,

Thank a lot  for your inputs and patch info.

It seems I cannot apply those patches straight away as it is based on 3.6-rc4 and I am using 3.4.25, between these two, it seems significant code changes for DSS related code.

I am using 3.4.25 kernel from TI for OMAP5 evm, it has been modified as per our platform requirement which is having OMAP5 ES2.0 revision.

I am trying to use the panel driver for DPI interface(i.e. Kernel\drivers\video\omap2\displays\panel-generic-dpi.c). So DSS and panel driver path are as follows

Kernel\drivers\video\omap2\dss\dpi.c,dss.c,display.c,dss_features.c etc

Kernel\drivers\video\omap2\displays\panel-generic-dpi.c

soc specific:
Kernel\arch\arm\mach-omap2\omap5_es2\clkt_clksel.c, clkt_dpll.c,clock.c,cm44xx_54xx.c etc

omapdrm path:
Kernel\drivers\staging\omapdrm

In case for working HDMI port, we are using:
Kernel\drivers\video\omap2\dss\hdmi.c
Kernel\drivers\video\omap2\dss\hdmi_panel.c

I think this would require considerable amount of understanding on dss architecture and effort to backport some of the things, write new driver fro TDF19988 and make DPI interface working for our platform for someone like me who has just started working on DSS/Display.

Regards,

Vikash

On Mon, May 12, 2014 at 5:28 PM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote:

On 12/05/14 14:33, Vikas Patil wrote:
> Hi,
>
> Re-posting as previous posting was rejected due to length.
>
> Forgot to mention, DPI pins are connected to TDF19988 chip for HDMI
> conversion.
> I have build the driver for it from
> https://gitorious.org/thierryreding/linux/source/e7792ce2da5ded80861db787ace9b57ecf7bc96c:drivers/gpu/drm/i2c/tda998x_drv.c.
> Is this the correct driver for it?

That driver cannot be used with omapdrm, which uses omapdss. There's no
TDF19988 driver for omapdss (at least in the mainline), so you need to
write one.

> Also I am trying to use the generic-dpi-panel driver for this with
> OMAP5. It seems I also need to add support for TDF19988 somewhere in
> omapdrm or lcd/panel driver by calling drm_i2c_encoder_init to
> initialize it. Can I use somecode from ticldc driver or driver itself?
> Could you please give some inputs, how should I proceed further to
> adding support for TDF19988 for which the input is coming from DPI
> interface?

You need to write a driver for it. Something similar to
drivers/video/fbdev/omap2/displays-new/encoder-tfp410.c, except tfp410
is quite simple one.

But I think you said you're based on some old customized kernel, so I
don't know which kind of omapdss driver you have there, so the mainline
tfp410 cannot probably be used as an example. Most likely the omapdss
drivers for your kernel are located in drivers/video/omap2/displays/
directory.

 Tomi

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