EDID and HowTo make one

krax · n00b Joined: 29 May 2011 Posts: 67 Location: Troy, MI

Hello;
I read the Post here https://www.osadl.org/Single-View.111M591850c02b5.0.html ; and i tried to make do with what i understood from the post but here are some questions:
1. where is the /lib/firmware located ;in for example /usr/src/linux/lib/firmware or /usr/lib/firmware or elsewhere?
2.Could i use a pre-build EDID in that address the post gave and tweak it with an editor like Gvim and pass it to kernel using the info bellow; the resolution i am trying is 1600x900@60

eyoung100 · Veteran Joined: 23 Jan 2004 Posts: 1428

What is your monitor type/brand etc :?:

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krax · n00b Joined: 29 May 2011 Posts: 67 Location: Troy, MI

Samsung SA300 over VGA100:02.0
VGA compatible controller: Intel Corporation Xeon E3-1200 v2/3rd Gen Core processor Graphics Controller (rev 09) { CONFIG_I915=y && CONFIG_I915_KMS=y }
KERNEL 3.10.7-gentoo-r1

eyoung100 · Veteran Joined: 23 Jan 2004 Posts: 1428

This may help: [Workaround] Define DisplaySize for External Monitor to Xorg Server
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salahx · Guru Joined: 12 Mar 2005 Posts: 530

KMS requires an EDID, and while you can override the EDID in org.conf, the plan is to get X11 away from the hardware and that will stop working. It is possible to override the EDID at the kernel level though. To do so, be sure CONFIG_DRM_LOAD_EDID_FIRMWARE is selected and passing drm_kms_helper.edid_firmware= one of the following 5 special parameters on the kernel command line, corresponding to the desired resolution:

Note that these values are hardcoded in the driver, there is no corresponding /lib/firmware file (although if it exists it will override the built-in ones)

It is possible to create custom EDID if needed: see Documentation/EDID/HOWTO.txt in the kernel sources for the details.

krax · n00b Joined: 29 May 2011 Posts: 67 Location: Troy, MI

I want to do in the kernel level because my problem is in tty mode and I want to know how to make (make file) (build) (compile) 1600*900 @60 from the source provided in the kernel git directory.
The main heck is providing numbers needed in source file; some could be find from CVT command but i don't now how and also the value for CRC also.
thanks

salahx · Guru Joined: 12 Mar 2005 Posts: 530

It depends on what's causing your problem. If the problem is due to a KVM switch, the east solution is boot Linux without the switch fetch the EDID from from sysfs (Use 'find /sys -iname edid' to find it), then copy it to the firmware directory (/lib/firmware/edid/edid.bin) and boto that way.

Otherwise go to /usr/src/linux/Documentation/EDID; cppy 1024x768.S to 1600x900.S and edit the values 1600x900.S to suit. You can look into edid.S as to what some of the values mean. XPIX should be 1600, YPIX should be 900, XY_RATIO should be XY_RATIO_16_9; but as far as the other stuff goes i'd either leave it as is or use the results from your monitor.

You get the results from your monitor, grab the edid file from sysfs above and emerge the read-edid utility. It contains the programs parse-edid, which you will need for 2 things. The first is to fetch the values of your existing monitor. The second is to figure out what the CRC you your new DID need to be (if its wrong, it'll tell you the correct value, simply set CRC to that value and rebuild)