Re: Intel graphics drm issue?

Mark Hounschell
2012-10-14T16:54:37Z

On 10/14/2012 07:03 AM, Bruno Prémont wrote:
> On Sun, 14 October 2012 Mark Hounschell <dmarkh@cfl.rr.com> wrote:
>> On 10/14/2012 04:41 AM, Bruno Prémont wrote:
>>> Your best solution is probably to write an EDID blob (or reuse one you find
>>> somewhere) that provides at least one mode matching your TV's native mode
>>> (probably full-HD).
>>>
>>> Google suggested the following document:
>>> http://www.jordansmanuals.com/ServiceManuals%5CLG%5CTV%5CLCD%5C42LB9DF%5C42LB9DF%20Service%20Manual.pdf
>>> which on page 13/14 shows the full EDID blob for the various HDMI outputs of the
>>> TV. You may want to read that document, convert the EDID blobs to 512 bytes binary
>>> files and hell DRM core to use the right one via module/kernel cmdline option:
>>>
>>> drm_kms_helper.edid_firmware=edid/lg42lb9df.edid
>>> or
>>> modprobe drm-kms-helper edid_firmware=edid/lg42lb9df.edid
>>>
>>> where
>>> /lib/firmware/edid/lg42lb9df.edid
>>> is the 512-bytes EDID blob created according to data from above manual.
>>> (note, that will only work for intel, radeon and nouveau drivers but will
>>> not work for closed drivers of AMD/nVidia)
>>>
>>
>> This certainly looks doable. That firmware file, should it contain all 4
>> tables or just the one for the port I'm connected to? Will it matter what
>> order they were in?
>
> It should contain just the table for the port you're connected to.
> For the HDMI ports the tables are 1024 bytes (e.g. two 512 bytes blocks,
> not just one as I incorrectly wrote above). For the VGA port it's just one
> 512 bytes block.
>
> Oh, and check the exact documentation of edid_firmware parameter as you can
> adjust its value to tell kernel to which connector exactly it applies
> (otherwise it will overwrite the EDID on other ports with working displays!).
>

Hi Bruno,

I've taken the EDID data from that service manual. I've looked at the
EDID-Howto for how to specify the connector but all I see is:

"An EDID data set will only be used for a particular connector,
if its name and a colon are prepended to the EDID name."

Where can I find the connector names?

And could I ask if this simple pgm might work to build the file I need?

int32_t main(int argc, char **argv)
{
FILE *fd;
const char *path = "/lib/firmware/edid/lg42lb9df.edid";
const char *mode = "w+";
uint8_t firmware[1024] = {

0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x1E,
0x6D, 0x01, 0x00, 0x01, 0x01, 0x01, 0x01,
0x0E, 0x10, 0x01, 0x03, 0x80, 0x73, 0x41, 0x96, 0x0A,
0xCF, 0x74, 0xA3, 0x57, 0x4C, 0xB0, 0x23,
0x09, 0x48, 0x4C, 0xAF, 0xCF, 0x00, 0x31, 0x40, 0x45,
0x40, 0x61, 0x40, 0x81, 0x80, 0xA9, 0x40,
0xD1, 0xC0, 0x01, 0x01, 0x01, 0x01, 0x02, 0x3A, 0x80,
0x18, 0x71, 0x38, 0x2D, 0x40, 0x58, 0x2C,
0x45, 0x00, 0xC4, 0x8E, 0x21, 0x00, 0x00, 0x1E, 0x66,
0x21, 0x50, 0xB0, 0x51, 0x00, 0x1B, 0x30,
0x40, 0x70, 0x36, 0x00, 0xC4, 0x8E, 0x21, 0x00, 0x00,
0x1E, 0x00, 0x00, 0x00, 0xFD, 0x00, 0x38,
0x4B, 0x1F, 0x44, 0x0F, 0x00, 0x0A, 0x20, 0x20, 0x20,
0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0xFC,
0x00, 0x4C, 0x47, 0x20, 0x54, 0x56, 0x0A, 0x20, 0x20,
0x20, 0x20, 0x20, 0x20, 0x20, 0x01, 0x15,

0x02, 0x03, 0x1B, 0xF1, 0x4C, 0x20, 0x22, 0x10, 0x1F,
0x01, 0x02, 0x03, 0x04, 0x05, 0x12, 0x93,
0x14, 0x23, 0x15, 0x07, 0x50, 0x65, 0x03, 0x0C, 0x00,
0x10, 0x00, 0x01, 0x1D, 0x00, 0x72, 0x51,
0xD0, 0x1E, 0x20, 0x6E, 0x28, 0x55, 0x00, 0xC4, 0x8E,
0x21, 0x00, 0x00, 0x1E, 0x01, 0x1D, 0x80,
0x18, 0x71, 0x1C, 0x16, 0x20, 0x58, 0x2C, 0x25, 0x00,
0xC4, 0x8E, 0x21, 0x00, 0x00, 0x9E, 0x8C,
0x0A, 0xD0, 0x90, 0x20, 0x40, 0x31, 0x20, 0x0C, 0x40,
0x55, 0x00, 0x4C, 0x6C, 0x42, 0x00, 0x00,
0x18, 0x01, 0x1D, 0x00, 0xBC, 0x52, 0xD0, 0x1E, 0x20,
0xB8, 0x28, 0x55, 0x40, 0x4C, 0x6C, 0x42,
0x00, 0x00, 0x1E, 0x01, 0x1D, 0x80, 0xD0, 0x72, 0x1C,
0x16, 0x20, 0x10, 0x2C, 0x25, 0x80, 0x4C,
0x6C, 0x42, 0x00, 0x00, 0x9E, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xED
};

fd = fopen(path, mode);
if (fd == NULL) {
perror("/lib/firmware/edid/lg42lb9df.edid failed: ");
return 1;
}

fwrite(&firmware, 1024, 1, fd);

fclose(fd);

printf("Wrote 1024 bytes of edid data to %s\n", path);

return 0;
}

Thanks very much
Mark