Re: intel drmkms

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Patrick Welche wrote:
>On Sat, Sep 20, 2014 at 11:40:16AM +0100, Robert Swindells wrote:
>> From adding some debug, the driver isn't able to read the EDID for the
>> LCD panel via i2c, it can read one for an external monitor though on
>> different pins.
>> 
>> A kernel built with 6.99.43 works on this machine but I can't see what
>> has changed since then that is causing the problem.
>
>It sounds as though you are following the path I ended up following:
>it turned out after more debug, that "old" code fell back to mapping
>a ROM and using resolution read from there, so the i2c (gmbus or
>something like that?) side doesn't work. AFAIR Taylor fixed that
>by enabling acpi so the ROM could be mapped...

The gmbus code does work when talking to the vga connector though.

I was wondering if it would work fully if the display probe was delayed
until interrupts are enabled.

>(pci_find_rom in include/linux/pci.h was failing)

The call to pci_find_rom fails too.

Running pcictl on the display controller device doesn't show an expansion
ROM at all.

>... question is what is different in your case, as Taylor fixed it for me...

Your problem with acpi may point to the answer.

It looks to me as if the driver needs to call the acpi _DDC method to
get the EDID if it can't map the ROM.

Robert Swindells