https://bugzilla.kernel.org/show_bug.cgi?id=172421 Bug ID: 172421 Summary: radeon: allow to set the TMDS frequency by a special kernel parameter Product: Drivers Version: 2.5 Kernel Version: 4.8.0-rc7+ Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: enhancement Priority: P1 Component: Video(DRI - non Intel) Assignee: drivers_video-dri@xxxxxxxxxxxxxxxxxxxx Reporter: estellnb@xxxxxxxxxx Regression: No Despite different claims by ATI in 2016 Radeon R5 230 graphics cards featuring HDMI, DVI and VGA had originally been sold as 4K-ready up to the year 2015. The only prove I have for this is a comercial invoice from Nexus Mobile and a packaging card. As far as I know Radeon R5 230 cards currently sold can still be run stable and reliable under UltraHD provided that you apply the right kernel patch (see for the attachement). Unfortunately neither my former merchant nor ATI have responded about my questions concerning this change in trade and marketing policy. My request would now be to integrate the provided patch into the mainline kernel. It does not change the behaviour of the radeon driver unless you specify a nonzero value for the radeon.hdmimhz parameter. If you do I have tested the R5 230 cards I have to run stable and reliably for days. At least the 2GB variant of this card has largely sufficient resources for proficient desktop computing under UltraHD including image manipulation in 3840x2160. While never officially discussed for the radeon driver nouveau is already implementing a similar parameter called nouveau.hdmimhz since kernel 4.5.x. Though it thereby becomes possible to specify a hdmimhz that is far above the cards technical possibilties the nouveau developers I have talked with say that it would rarely be possible to damage any card by overcloking the TMDS. In deed I have successfully been overclocking my GeForce 9600M GT to feature 4K/2160p. Even specifying values considerable higher than 225MHz did not damage my GeForce 9600M GT though the screen stayed black upon the nouveau driver initialization. While the Radeon R5 230 works well at 297MHz (as long as you specify that via radeon.hdmimhz) I have similarly to the GeForce 9600M GT tried to overclock a Radeon R7 240. It did produce stable images at a higher hdmimhz like 330 though the HDMI input of my monitor features no more than 30Hz at 3840x2160 (tested with or without a DP-adapter). While it remains questionable if the provided patch can improve things for newer Radeon cards I would believe it to be beneficial for some elder cards. At least it is known to be beneficial for the R5 230 initially marketed as 4K-ready. The according radeon patch provided with this report has so far already been accepted by the Mageia 6 distribution. Though the attached patch is for application at the current 4.8.0-rcX+ kernels most of my machines that rely on it still run with 4.6.0. -- You are receiving this mail because: You are watching the assignee of the bug. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
