| Bug ID | 105302 |
|---|---|
| Summary | [DC] - Maximum pixel clock of dual-link DVI too low for some = modes |
| Product | DRI |
| Version | DRI git |
| Hardware | x86-64 (AMD64) |
| OS | Linux (All) |
| Status | NEW |
| Severity | normal |
| Priority | medium |
| Component | DRM/AMDgpu |
| Assignee | dri-devel@lists.freedesktop.org |
| Reporter | asheldon55@gmail.com |
I have a monitor that supports 2560x1440 >60hz (up to aroun= d 110hz) through the DVI-D interface but requires pixel clocks greater than the current dual-link limit of 330khz, with amdgpu.dc=3D1. Setting TMDS_MAX_PIXEL_CLOCK to 250000= in signal_types.h works around the problem.=20 amdgpu.dc=3D0 doesn't appear to have this limit (or the value is higher) so= the problem does not exist there. I'm using ~ag5df's drm-next-4.17-wip branch. There appears to be a discussion about setting a higher pixel clock limit in this bug: https://bugs.freedesktop.org/show_bug.c= gi?id=3D93885 but focused on HDMI and not DVI-D, and regarding the older radeon driver.
| What | Removed | Added |
|---|---|---|
| CC | harry.wentland@amd.com |
The non-DC code should really have limited this too. It's pro= bably a bug there. As to what the actual limit is, hopefully Harry can comment on that= .
I don't have the spec right now but wikipedia has a nice run-d= own of the DVI bounding box: https://en.wikipedia.org/wiki/Digital_Visual_Interface#Digita= l Basically 2560x1600 @ 60Hz is the highest allowed for dual-link, which = is just a tad above your 2560x1440 @ 60Hz. 110Hz at full resolution would defin= itely not be supported by DVI. What monitor are you using? Is it intended to support 110Hz at full resolut= ion on DVI? Could it be that this full monitor capabilities are only supported through DP?
(In reply to Harry Wentland from comment #2) > I don't have the spec right now but wikipedia ha= s a nice run-down of the DVI > bounding box: https://en.wikipedia.org/wiki/Digital_Visual_Interface#D= igital >=20 > Basically 2560x1600 @ 60Hz is the highest allowed for dual-link, w= hich is > just a tad above your 2560x1440 @ 60Hz. 110Hz at full resolution w= ould > definitely not be supported by DVI. >=20 > What monitor are you using? Is it intended to support 110Hz at full > resolution on DVI? Could it be that this full monitor capabilities are= only > supported through DP? It's a cheap Korean monitor that only supports DVI-D (Qnix qx2710 single in= put version), and unofficially supports greater than 60hz. You're right, it's a= bove DVI-D spec but it would be nice to have an option to use higher pixel clocks nevertheless. The Nvidia binary drivers have the option for ignoring the pi= xel clock check so there is at least one example of this being supported in the wild.
This sounds like a feature request, rather than a bug.
| What | Removed | Added |
|---|---|---|
| Severity | normal | enhancement |
I'd rather not support running things out of spec in the drive=
r. The source is
open. If you want to adjust the code allow something like that you can.
(In reply to Alex Deucher from comment #5) > I'd rather not support running things out of spe= c in the driver. The source > is open. If you want to adjust the code allow something like that you= can. Fair enough, it's simple enough to patch the source for a higher limit.
| What | Removed | Added |
|---|---|---|
| Status | NEW | RESOLVED |
| Resolution | --- | MOVED |
-- GitLab Migration Automatic Message -- This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity. You can subscribe and participate further through the new bug through this = link to our GitLab instance: https://gitlab.freedesktop.org/drm/amd/issues/319.