drm_kms_helper problems

From: Mark Hounschell
Date: Sun Oct 21 2012 - 10:43:00 EST

I have a TV that appears to not provide proper EDID info to the HDMI or DVI ports of my Intel DH77DF motherboard. I received some pointers from this list that pointed me in the direction of creating my own EDID file and I now have a binary blob that matches what the service manual says is the proper EDID info.

But I am unable to get the drm_kms_helper module to load and use this file. My relevant kernel config options are.


my relevant kernel command line contains:

video=card0-HDMI-A-1:e drm_kms_helper.edid_firmware=card0-HDMI-A-1:edid/lg42lb9df_hdmi1.edid

The edid file:
# ls -al /lib/firmware/edid/lg42lb9df_hdmi1.edid
-rw-r--r-- 1 root root 256 Oct 16 05:46 /lib/firmware/edid/lg42lb9df_hdmi1.edid

connector info from /sys/class/drm/

card0 card0-DP-1 card0-DP-2 card0-DP-3 card0-HDMI-A-1 card0-HDMI-A-2 card0-HDMI-A-3 card0-VGA-1 controlD64 version

And I don't really understand why I have 3 entries for the one hdmi port? Nor do I really understand _exactly_ how to define the connector in my kernel command line or which of the 3 connectors from /sys I should be using. I've tried different variants. Ie. card0-HDMI-A-1and HDMI-A-1.

The results in the kernel log file remain:

[ 1.879654] drm_kms_helper: Unknown parameter `edid'

I assume I am doing something wrong but I have put some debug printks in kernel/params.c that shows me every call made to it and it's params. It is entered many times and I see a sequence to in the log file. As an example, the last one to call with params before drm_kms_helper is "late" and here are my debug prints for it:

[ 0.840206] parse_args: Entered for late
[ 0.840207] parse_args: doing = late
[ 0.840208] parse_args: args = root=/dev/disk/by-id/ata-INTEL_SSDSC2CW060A3_CVCV205106EB060AGN-part4 video=1024x768 resume=/dev/disk/by-id/ata-INTEL_SSDSC2CW060A3_CVCV205106EB060AGN-part3 splash=silent quiet vga=0x37e irqpoll video=card0-HDMI-A-1:e drm_kms_helper.edid_firmware=card0-HDMI-A-1:edid/lg42lb9df_hdmi1.edid
[ 0.840209] parse_args: params =
[ 0.840210] parse_args: num = 174
[ 0.840210] parse_args: min_level = 7
[ 0.840211] parse_args: max_level = 7

Now when it gets to drm_kms_helper this is what I get and this is certainly screwed up, I just don't know why.

[ 1.879648] parse_args: Entered for drm_kms_helper
[ 1.879648] parse_args: doing = drm_kms_helper
[ 1.879649] parse_args: args = edid
[ 1.879650] parse_args: num = 2
[ 1.879651] parse_args: min_level = -32768
[ 1.879651] parse_args: max_level = 32767
[ 1.879653]
\xffffff86\xffffffe2\xfffffff8h\xffffff89\xffffff86\xffffffc0\xffffff80\xffffffff\xffffffffÔ\xffffffe2\xfffffff8T\xffffff86\xffffffe2\xfffffff88\xffffff89\xffffff86\xffffffc0\xffffffa4\xffffffff\xffffffffd\xffffff86\xffffffe2\xfffffff8, num=2, min_level=-32768, max_level=32767

Then finally:

[ 1.879654] drm_kms_helper: Unknown parameter `edid'

The additional printks I inserted into kernel/params.c:

if (*args)
pr_debug("doing %s, parsing ARGS: '%s'\n", doing, args);

+ if (*args) {
+ printk("\nparse_args: Entered for %s\n", doing);
+ printk("parse_args: doing = %s\n", doing);
+ printk("parse_args: args = %s\n", args);
+ printk("parse_args: params = %s\n", params);
+ printk("parse_args: num = %d\n", num);
+ printk("parse_args: min_level = %d\n",min_level);
+ printk("parse_args: max_level = %d\n", max_level);
+ }

while (*args) {

This is using a vanilla 3.6.2 kernel. Any help would be appreciated.


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