Date: Sun, 30 Dec 2018 22:46:07 +0100 From: =?UTF-8?B?VMSzbA==?= Coosemans <tijl@FreeBSD.org> To: Andrea Venturoli <ml@netfence.it> Cc: freebsd-x11@freebsd.org Subject: Re: Radeon HD 4250: screen going blank every few seconds Message-ID: <20181230224607.1feb9cad@kalimero.tijl.coosemans.org> In-Reply-To: <4560f9e2-efcf-a1f5-728c-c26fcec34353@netfence.it> References: <4560f9e2-efcf-a1f5-728c-c26fcec34353@netfence.it>
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On Sun, 30 Dec 2018 20:29:49 +0100 Andrea Venturoli <ml@netfence.it> wrote: > I've got a desktop which used a Radeon HD 4200 with no troubles: I was > using a 1920x1200 monitor on the DVI port and occasionally a second one > on the VGA port; this system had no HDMI port. > > > > Now I changed mainboard with an Asus M5A88-V Evo (latest BIOS > installed), which features a Radeon HD 4250 and I'm getting some troubles. > > Focusing only on one monitor, it works fine if connected to the VGA > port, but I'd like to avoid this setup because: > a) begin analogic, it shows some background noise; > b) it won't allow me to use the second monitor. > > So I'd like to use either the HDMI or the DVI port, but in this case: > _ the system start fine and is stable as long as BIOS resolution is used; > _ as soon as I "service kld start" and the resolution switchs to > 1920x1200 the screen starts flickering: every 1-2 seconds the image goes > black (the monitor displaying "DVI Input" or "HDMI Input" as if a new > signal was detected) and gets back to normal in another 1-2 seconds; > _ once XOrg is up and running the problem does NOT disappear. > > As I suspected an hardware problem, I tried booting Knoppix: initially I > get the same behaviour (works fine, then starts flickering once the > resolution is increased); however, after XOrg is running the problem stops. > So, either it isn't an hardware problem or there is a workaround. > > Also worth mentioning: > _ if I decrease the resolution to 1920x1080 everything is ok, of course > apart seeing two black areas on the top and bottom of my screen :( > _ while keeping full resolution, attaching the second monitor on the VGA > port *and enabling it* will reduce the flickering from every 1-2 seconds > to every 5-10 seconds. > > > > > So I'm asking for some help, since either using the VGA port or > decreasing the resolution is not a workaround I'm eager to adopt; is > there anything that can be done? Some sysctl? Some BIOS settings? Some > xorg.conf tweak? Some update to test? > > I tried and searched if this was a known (or at least previously seen) > problem, but came up empty. > Even some pointer to documentation/knowledge base would help... Try running "sysctl compat.linuxkpi.hw_i2c=0".
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