Setting custom HDMI timing for i.MX8 Quad Max

[yavuz_mutlu]

Hi all,

We are trying to add support for non-standard HDMI display timings for our display. As far as I understand we need to add clock support for our DRM mode which is

{ DRM_MODE("4096x640", DRM_MODE_TYPE_DRIVER, 175560, 4096, 4144,
4188, 4290, 0, 640, 672, 674, 682, 0,
DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_NVSYNC),
.vrefresh = 60, },

I don't think i.MX 8 QM with 5.4.70 kernel supports 175560 clock frequency. In some other questions people mentioned and added some patches to support their timings, however, I think HDMI driver structure has completely changed for this kernel (and the documentation https://www.nxp.com/docs/en/reference-manual/IMX_REFERENCE_MANUAL.pdf seems to be wrong).

How to add custom clock support for our timings?

Thanks in advance.

[IvanRuiz]

Hello,

The first thing would be to check if that specific frequency can be achieved by some of the available clock sources. For the latest Linux docs (L5.4.70_2.3.1_LINUX_DOCS), you may refer to the following link in which in table 5 you will find the link for the i.MX Graphics DRM's repo: https://www.nxp.com/webapp/Download?colCode=L5.4.70_2.3.1_LINUX_DOCS 

Hope it helps!

BR,

Ivan.