Re: further issues with MGA G200 graphics chipset

[stuart hayes]

On 4/27/2026 7:14 AM, Thomas Zimmermann wrote:
> Hi
>
> Am 25.04.26 um 01:29 schrieb Jacob Keller:
> [...]
> > > So I suggest to pick Manufacturer, Product, Version as key. I'd be
> > > surprised if we find more than a hand full of systems with the issue. If
> > > we see a trend or common pattern, we can generalize later on.
> > I think this is the best solution. Keep it focused for now. I believe
> > Intel has two major platforms that we care about with respect to this
> > issue. I'll see if I can dig up the data. The systems install the MGA
> > G200 for BMC use but don't seem to expose the VGA connection.
> >
> > For the specific system I have that was faulty, we have the following:
> >
> > $ for t in system-manufacturer system-product-name system-version ; \
> >      do dmidecode -s ${t}; \
> > done
> > Dell Inc.
> > PowerEdge XR8720t
> > Not Specified
> >
> >
> >
> > I believe there was also some concern about HP systems which similarly
> > use this chipset, but I don't have the DMI data for that one off hand.
> > I've asked some colleagues to confirm the situation and obtain that
> > data. I'll get back early next week if we think there are any other
> > systems possibly affected.
> >
> > In the mean time, I'm happy to have our team test any patch to confirm
> > that it behaves as expected and resolves the service interruptions.
>
> For now, I've modified the two places that have BMC support in the 
> driver. Could you please also tell me your system's exact Matrox chipset 
> or its PCI id?
>
> The patch is attached for your testing. It would work against drm-tip or 
> v7.1-rc1.
>
> I've also found the page at [1], which claims that there's a Mini-DP 
> port at the front. If so, I'd assume that there's also an extra encoder 
> chip to replace the VGA. If we ever get specs for that, we could 
> implement real support in the driver.
>
> In the meantime, the current fix should work. In the worst case, that 
> Mini-DP port would give a lower default resolution.
>
> [1] https://www.dell.com/en-us/shop/ipovw/poweredge-xr8720t? 
> hve=shop+now#techspecs_section
>
> Best regards
> Thomas

So this patch disables DDC polling if the dmi_check_system() matches. If 
this was to happen on systems that _do_ have a physical VGA connector, 
will that port still be active, just with a resolution that may not be 
compatible with the monitor that's plugged in?

I don't see anyone say that the DDC polling doesn't cause too much 
latency for real time kernels on other systems that do have a VGA 
connector... did I miss that, or is there a chance that a lot of other 
systems that use this driver might also have issues with a real time kernel?


> > Appreciate all the feedback on this thread.
> >
> > Thanks,
> > Jake