[drm] Cannot find any crtc or sizes

[hongxingyu1982]

Hi sir

Now I would like bring up the lcdif (mipi-to-hdmi) imx8mq board, the mixel_mipi_phy_probe、adv7511_probe、nwl_dsi_probe、imx_nwl_dsi_probe  run ok, all the devices attach the driver. But when it runs in linux-imx/drivers/gpu/drm/drm_fb_helper.c, it reports the error as blew:

[drm] Cannot find any crtc or sizes

Could you help me check the error?

Attachment is the detailed log， please check。

Thanks

BR

[igorpadykov]

Hi Hongxing

from log: " picking CRTCs for 1280x720 config
.. drm_fb_helper_single_fb_probe: 1837: desired_mode is null.
...[drm] Cannot find any crtc or sizes"

seems there are problems with configuring panel settings with cea modes,

one can try to debug it in ..gpu/drm/drm_edid.c

Also one can use latest Linux L4.19.35_1.1.0  
linux-imx - i.MX Linux kernel 

and try solutions provided on Display pixel clock limitation to 74.25 MHz 

Best regards
igor
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[hongxingyu1982]

Hi, igorpadykove

Thank you so much for your reply. I will try.

By the way, does the lcdif (mipi-to-hdmi) need the gpu support ? should we enable the gpu for it ?

Br

thanks

[igorpadykov]

Hi Hongxing

in general gpu is not needed, display interfaces are described in

sect.13.1 Multimedia Overview i.MX8MQ Reference Manual

Best regards
igor

[hongxingyu1982]

Hi，igor:

Thank you so much. Yes, you are right, It seems the gpu is not need. Now the fb0 create sucessfully. But when I handle the /dev/fb0 with the test demo, there is no report error, but there is no display content in the mipi-dsi panel,. attachment is the log, Could you help to check it.

[igorpadykov]

Hi Hongxing

as described in sect.6.2.2 "Frame Buffer"  Linux Manual from Linux 4.14.98_2.2.0 Documentation

Frame buffer drivers are supported for i.MX 6 and i.MX 7 but not for i.MX 8.

Best regards
igor