[Openchrome-devel] [Bug 94528] HDMI port is not working on current KMS driver with VX900 platform

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=94528

--- Comment #13 from HuangRan <huangranbj at 126.com> ---
With my past two weeks' work, I have finished analyzing HDMI port mode setting
mode in via open source KMS driver.
Actually the whole mode setting process phases can be divided into several
phases:
   1) EDID probe and EDID processing to generate a list of modes(CEA, EST, DTL,
STD), then select the best mode to do the mode set. At the same time, in this
phase, encoder and connector are chose out for HDMI port(that should be TMDS
for encoder and HDMIA for the connector). 
     And for via open source driver, it probes out the VBIOS information from
the BIOS and get DI port informaiton(including VCP information) and get
supported devices list and then I2C ping pang probe(For my VX900 board, it is
S3_CRT|S3_DVI|S3_HDMI|S3_DP). 
    After that it uses 0xC0C4, 0C0C8 registers to ask if the HDMI monitor is
present, if that is so, probe 256 bytes EDID information and do analysis.
   2) If we are using fb device, it will pick up correct crtc device for the
HDMI encoder and connector.
   3) then the control is given back to fb device, and real mode setting will
be done. encoder and crtc funcs(prepare, mode_set, commit) will be done in this
process. Especially some HDMI PHY registers are set and Info Frame registers
are set(although audio registers are set)
   4)after the commit of encoder is done, the monitor will be lighten up.

So right now with the X logs for OpenChrome KMS driver, the EDID is probed out
but the monitor is not showning anything, I thought the issue should be in the
process 3). So I will begin to check OpenChrome KMS HDMI mode setting function
to see if HDMI PHY and INFO Frame registers are set properly.

The most difficult thing is that in VX900 OGPM, there is no registers
definition for HDMI port and VIA does not plan to release it because of the IP
protection. So I have to figure it out by my debugging and understanding.

Thanks,
Frank

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