Re: further issues with MGA G200 graphics chipset

[stuart hayes <stuart.w.hayes@gmail.com>]

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
>