On Tue, Jun 04, 2019 at 11:18:06AM +0300, Jani Nikula wrote: > On Mon, 03 Jun 2019, Harish Chegondi <harish.chegondi@xxxxxxxxx> wrote: > > On Wed, May 29, 2019 at 01:22:30PM +0300, Jani Nikula wrote: > >> On Wed, 29 May 2019, Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxx> wrote: > >> > On Tue, 28 May 2019, Jani Nikula wrote: > >> > > >> >> On Mon, 27 May 2019, Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx> wrote: > >> >> > On Sun, 26 May 2019 12:50:51 -0700, Ilpo Järvinen wrote: > >> >> >> > >> >> >> Hi all, > >> >> >> > >> >> >> I've a workstation which has internal VGA that is detected as AST 2400 and > >> >> >> with it EDID has been always quite flaky (except for some time it worked > >> >> >> with 4.14 long enough that I thought the problems would be past until the > >> >> >> problems reappeared also with 4.14). Thus, I've provided manually the EDID > >> >> >> that I extracted from the monitor using other computer (the monitor itself > >> >> >> worked just fine on the earlier computer so it is likely fine). > >> >> >> > >> >> >> I setup the manual EDID using drm_kms_helper.edid_firmware, however, > >> >> >> after upgrading to 4.19.45 it stopped working (no "Got external EDID base > >> >> >> block" appears in dmesg, the text mode is kept in the lower res mode, and > >> >> >> Xorg logs no longer dumps the EDID info like it did with 4.14). So I guess > >> >> >> the EDID I provided manually on the command line is not correctly put into > >> >> >> use with 4.19+ kernels. > >> >> >> > >> >> >> The 4.19 dmesg indicated that drm_kms_helper.edid_firmware is deprecated > >> >> >> so I also tested with drm.edid_firmware it suggested as the replacement > >> >> >> but with no luck (but I believe also the drm_kms_helper one should have > >> >> >> worked as it was only "deprecated"). > >> >> >> > >> >> >> I also tried 5.1.2 but it did not work any better (and with it also tried > >> >> >> removing all the manual *.edid_firmware from the command line so I still > >> >> >> need to provide one manually to have it reliable working it seems). > >> >> > > >> >> > I believe there is a bug already tracking this, here: > >> >> > > >> >> > https://bugs.freedesktop.org/show_bug.cgi?id=107583 > >> >> > >> >> Ilpo, does video=VGA-1:e command-line option work around the problem for > >> >> you? > >> > > >> > Yes it does; together with the modeline stuff for Xorg (after reading the > >> > referenced bug report I realized I can fix the X side with it). So I now > >> > have the desired modes/resolutions in use. Thank you all! > >> > >> Great! It should be enough to just have the replacement firmware EDID > >> for the modes, as long as you have an EDID that represents the > >> capabilities of the display. The modelines for Xorg should not be > >> needed. > >> > >> BR, > >> Jani. > >> > > > > Ilpo, > > > > I have a patch which I think will fix this problem without needing > > the video=VGA-1:e command-line option work around. Will you be able to > > help me with testing it on your system? > > Alas the patch you provided in the referenced bugzilla will regress in > other ways; specifically losing the ability to use DDC probe for > detecting displays. This is very old happy day scenario functionality > that should not be messed with. > > BR, > Jani. Hi Jani, Please allow me to explain the reason behind my patch which I came up after analyzing the code in drm_get_edid() and drm_do_get_edid(). I see the DDC probe function drm_probe_ddc() only calls drm_do_probe_ddc_edid(adapter, &out, 0, 1). So, it is probing by reading 1 byte of EDID data via I2C. With my patch which I pasted below for reference, drm_probe_ddc() is not called but drm_do_get_edid() is called with drm_do_probe_ddc_edid() passed as a function pointer argument. drm_do_get_edid() function first handles the EDID override case and then calls drm_do_probe_ddc_edid(data, edid, 0, EDID_LENGTH) via function pointer argument get_edid_block. So, even with my patch, isn't the code probing the display by calling drm_do_probe_ddc_edid(, , , EDID_LENGTH) which reads EDID_LENGTH bytes of EDID data via I2C? The only difference is that drm_probe_ddc() probes the display by reading just 1 byte of EDID data. Please let me know your thoughts on my analysis. Thank You! Harish. diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index d87f574feeca..41c420706532 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -1724,9 +1724,6 @@ struct edid *drm_get_edid(struct drm_connector *connector, if (connector->force == DRM_FORCE_OFF) return NULL; - if (connector->force == DRM_FORCE_UNSPECIFIED && !drm_probe_ddc(adapter)) - return NULL; - edid = drm_do_get_edid(connector, drm_do_probe_ddc_edid, adapter); if (edid) drm_get_displayid(connector, edid); > > > -- > Jani Nikula, Intel Open Source Graphics Center _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
