In March I had developed a kernel patch that allows to set the TMDS frequency for radeon cards by a new kernel parameter called radeon.hdmihz if the automatically set frequency stays either behind of what has been advertised for the card or by what is achievable through overclocking. A similar parameter for nvidia/nouveau cards is already available somewhat longer. However up to now the patch has not been accepted into the mainline kernel simply because radeon developers are not encouraged to enable this feature for elder cards by the policy of their sponsors. Here are some of my considerations which you should take into account when deciding about the acceptance of the patch for Mageia 6:
* the patch is very simple, just a few lines of code
* behaviour of the kernel is not influenced by the patch except when the user gives a non-zero value for radeon.hdmimhz
* the patch has already wheathered time; the surrounding code has more or less remained unchanged since March
* long time usage experience is already available at least with the radeon R5 230 card as well as different monitors; my personal experience with the patch is very good
* the patch provides a huge advantage at least for all people who still use Core 2 based systems:
- elder radeon cards can be made UHD ready
- the R5 230 card supported by the patch may be the only one of its type that has a single slot height - and it has been sold to me as DVI-UHD ready; however this feature can not be exploited without the kernel patch
- newer radeon cards are often incompatible with elder Core 2 systems
* at least nouveau developers say that by overclocking your TMDS it would rarely be possible to damage a card; a way of proceeding considered safe can be read in the linked article (unfortunately that one is not as up to date as would be desireable; however when the patch gets accepted by Mageia then I can promise to rework it).
Created attachment 8362 [details]
patch introducing radeon.hdmimhz for kernel 4.8.0-rc2
Created attachment 8363 [details]
patch introducing radeon.duallink for kernel 4.8.0-rc2 (optional)
This patch introduces another kernel parameter called radeon.duallink. It is only taken into account if radeon.hdmimhz is non-zero. The usedfulness of this patch has not been proven yet as I lack respective hardware for testing.
Release (media or process) =>
RPM PackagesSource RPM:
Thanks for the patches.
Would you be willing to look into this, e.g. when you're starting to work on the kernel 4.8.0-rc2 updates? (I'm starting to get the feeling there's a new kernel everyday ;-) )
If so, then please assign to yourself.
If not (and until we can assign to kernel-group or so), then please assign to email@example.com
Assigning to all packagers collectively, since our registered kernel maintainer went MIA.
(There are two suggested patches attached to this report)
reassigning, now that we have a kernel packagers group
Mageia 6 =>
Kudos to Elmar - patch works great on my Archlinux box with Radeon HD6670 and HP E272q (2560x1440@60Hz).
Has it been integrated to Mageia yet? Will it be further maintained, e.g. adapted for Kernel 4.10?
Are there any attempts / chances for the patch to be integrated into mainline?
Kernel 4.10 is on the horizon and I'd like to get in touch with devs and users of the patch because there are not so many places on the internet with the patch mentioned - apart from Elmar's homepage and https://bugs.freedesktop.org/show_bug.cgi?id=93885 (yes, it's me there on comment #24).