Re: further issues with MGA G200 graphics chipset

[Jacob Keller]

On 4/27/2026 5:14 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?
> 

Here's the lspci output:

> 
> b5:00.0 VGA compatible controller [0300]: Matrox Electronics Systems Ltd. Integrated Matrox G200eW3 Graphics Controller [102b:0536] (rev 08) (prog-if 00 [VGA controller])
>         DeviceName: Embedded Video
>         Subsystem: Dell Integrated Matrox G200eW3 Graphics Controller [1028:0d38]
>         Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
>         Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
>         Interrupt: pin A routed to IRQ 16
>         NUMA node: 0
>         IOMMU group: 16
>         Region 0: Memory at e5000000 (32-bit, prefetchable) [size=16M]
>         Region 1: Memory at e6810000 (32-bit, non-prefetchable) [size=16K]
>         Region 2: Memory at e6000000 (32-bit, non-prefetchable) [size=8M]
>         Capabilities: [dc] Power Management version 3
>                 Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
>                 Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
>         Kernel driver in use: mgag200
>         Kernel modules: mgag200

The device ID looks to be 0x0536, and the subdevice ID is Dell 0x0D38. I
don't see anything specifically related to mini display port. It is
plausible there is an encoder between that output and the G200eW3.

> The patch is attached for your testing. It would work against drm-tip or
> v7.1-rc1.
> 

I'll give it a shot.

> 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.
> 

There does appear to be a mini display port cable. I am not certain if
that is driven from the Matrox graphics or not, but looking at lspci
there doesn't appear to be any other graphics chipset on the system, so
you might be right, but I am not certain.

> In the meantime, the current fix should work. In the worst case, that
> Mini-DP port would give a lower default resolution.
> 

I can check the behavior of the mini-DP output too and see if this
changes anything for it.

> [1] https://www.dell.com/en-us/shop/ipovw/poweredge-xr8720t?
> hve=shop+now#techspecs_section
> 
> Best regards
> Thomas
> 
> 
> 
> 
>>
>> Appreciate all the feedback on this thread.
>>
>> Thanks,
>> Jake
>