Re: drm/mgag200: Fix big-endian support

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 02.08.26 um 20:06 schrieb Christian Zigotzky:
> Hello René,
>
> Many thanks for your patch. [1]
>
> I have bought the PCI graphics card Matrox G200 G2+/QUADP-PL/7 32MB with 4x DVI. It is an AGP card connected via PCI.
>
> We use the new DRM driver MGAG200 since the kernel 7.2.0-rc4 and the old DRM legacy driver for Matrox g200/g400 graphics cards since the stable long-term kernel 5.10.260.
>
> I tested it with the RC5 of kernel 7.2 in my PowerPC machine (e5500) today. Unfortunately, the DRM driver mgag200 can't read the PCI ROM. Maybe only an x86 ROM?

This comment in the rsp fbdev driver might explain what's happening here:

https://elixir.bootlin.com/linux/v7.2/source/drivers/video/fbdev/matrox/matroxfb_misc.c#L501

>
> xrandr detects the ports but reports that they are not connected, even though the cables are plugged in.
>
> I also tested it with the stable long-term kernel 5.10.261 with the old legacy DRM drivers for Matrox graphics cards.
> I installed the Xorg MGA server xf86-video-mga-2.0.0_3 for the old legacy DRM driver but unfortunately I get only a black screen.
>
> Is it possible to use this card with PPC Linux?

Doing ROM-parsing as the same as old driver does could possibly resolve 
the issue.  If nothing else shows up, I'll take a look at it.

Best regards
Thomas


>
> More information:
>
> lspci -vvv
>
> 0001:05:00.0 VGA compatible controller: Matrox Electronics Systems Ltd. MGA G200 AGP (rev 03) (prog-if 00 [VGA controller])
> 	Subsystem: Matrox Electronics Systems Ltd. G200 Multi-Monitor
> 	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-
> 	Latency: 128 (4000ns min, 8000ns max), Cache Line Size: 32 bytes
> 	Interrupt: pin A routed to IRQ 18
> 	Region 0: Memory at c20000000 (32-bit, prefetchable) [size=16M]
> 	Region 1: Memory at c21000000 (32-bit, non-prefetchable) [size=16K]
> 	Region 2: Memory at c21800000 (32-bit, non-prefetchable) [size=8M]
> 	Expansion ROM at c21010000 [disabled] [size=64K]
> 	Capabilities: [dc] Power Management version 1
> 		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
> 		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
> 	Capabilities: [f0] AGP version 1.0
> 		Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW- AGP3- Rate=x1,x2
> 		Command: RQ=1 ArqSz=0 Cal=0 SBA- AGP- GART64- 64bit- FW- Rate=<none>
> 	Kernel driver in use: mgag200
>
> 0001:05:04.0 Display controller: Matrox Electronics Systems Ltd. MGA G200 AGP (rev 03)
> 	Subsystem: Matrox Electronics Systems Ltd. G200 Multi-Monitor
> 	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-
> 	Latency: 128 (4000ns min, 8000ns max), Cache Line Size: 32 bytes
> 	Interrupt: pin A routed to IRQ 18
> 	Region 0: Memory at c22000000 (32-bit, prefetchable) [size=16M]
> 	Region 1: Memory at c23000000 (32-bit, non-prefetchable) [size=16K]
> 	Region 2: Memory at c23800000 (32-bit, non-prefetchable) [size=8M]
> 	Expansion ROM at c21020000 [disabled] [size=64K]
> 	Capabilities: [dc] Power Management version 1
> 		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
> 		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
> 	Capabilities: [f0] AGP version 1.0
> 		Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW- AGP3- Rate=x1,x2
> 		Command: RQ=1 ArqSz=0 Cal=0 SBA- AGP- GART64- 64bit- FW- Rate=<none>
> 	Kernel driver in use: mgag200
>
> 0001:05:08.0 Display controller: Matrox Electronics Systems Ltd. MGA G200 AGP (rev 03)
> 	Subsystem: Matrox Electronics Systems Ltd. G200 Multi-Monitor
> 	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-
> 	Latency: 128 (4000ns min, 8000ns max), Cache Line Size: 32 bytes
> 	Interrupt: pin A routed to IRQ 18
> 	Region 0: Memory at c24000000 (32-bit, prefetchable) [size=16M]
> 	Region 1: Memory at c25000000 (32-bit, non-prefetchable) [size=16K]
> 	Region 2: Memory at c25800000 (32-bit, non-prefetchable) [size=8M]
> 	Expansion ROM at c21030000 [disabled] [size=64K]
> 	Capabilities: [dc] Power Management version 1
> 		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
> 		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
> 	Capabilities: [f0] AGP version 1.0
> 		Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW- AGP3- Rate=x1,x2
> 		Command: RQ=1 ArqSz=0 Cal=0 SBA- AGP- GART64- 64bit- FW- Rate=<none>
> 	Kernel driver in use: mgag200
>
> 0001:05:0c.0 Display controller: Matrox Electronics Systems Ltd. MGA G200 AGP (rev 03)
> 	Subsystem: Matrox Electronics Systems Ltd. G200 Multi-Monitor
> 	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-
> 	Latency: 128 (4000ns min, 8000ns max), Cache Line Size: 32 bytes
> 	Interrupt: pin A routed to IRQ 18
> 	Region 0: Memory at c26000000 (32-bit, prefetchable) [size=16M]
> 	Region 1: Memory at c27000000 (32-bit, non-prefetchable) [size=16K]
> 	Region 2: Memory at c27800000 (32-bit, non-prefetchable) [size=8M]
> 	Expansion ROM at c21040000 [disabled] [size=64K]
> 	Capabilities: [dc] Power Management version 1
> 		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
> 		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
> 	Capabilities: [f0] AGP version 1.0
> 		Status: RQ=32 Iso- ArqSz=0 Cal=0 SBA+ ITACoh- GART64- HTrans- 64bit- FW- AGP3- Rate=x1,x2
> 		Command: RQ=1 ArqSz=0 Cal=0 SBA- AGP- GART64- 64bit- FW- Rate=<none>
> 	Kernel driver in use: mgag200
>
>
> dmesg | grep -i mga
>
> [    2.302206] [drm] Initialized mgag200 1.0.0 for 0001:05:00.0 on minor 1
> [    2.303761] mgag200 0001:05:00.0: [drm] Cannot find any crtc or sizes
> [    2.304697] mgag200 0001:05:04.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0xffff
> [    2.305792] [drm] Initialized mgag200 1.0.0 for 0001:05:04.0 on minor 2
> [    2.308281] mgag200 0001:05:04.0: [drm] Cannot find any crtc or sizes
> [    2.308802] mgag200 0001:05:08.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0xffff
> [    2.309319] [drm] Initialized mgag200 1.0.0 for 0001:05:08.0 on minor 3
> [    2.309785] mgag200 0001:05:00.0: [drm] Cannot find any crtc or sizes
> [    2.310900] mgag200 0001:05:08.0: [drm] Cannot find any crtc or sizes
> [    2.311895] mgag200 0001:05:0c.0: Invalid PCI ROM header signature: expecting 0xaa55, got 0xffff
> [    2.312633] [drm] Initialized mgag200 1.0.0 for 0001:05:0c.0 on minor 4
> [    2.312844] mgag200 0001:05:04.0: [drm] Cannot find any crtc or sizes
> [    2.315512] mgag200 0001:05:0c.0: [drm] Cannot find any crtc or sizes
> [    2.317178] mgag200 0001:05:08.0: [drm] Cannot find any crtc or sizes
> [    2.323318] mgag200 0001:05:0c.0: [drm] Cannot find any crtc or sizes
>
> xrandr
>
> …
>
> VGA-4-4 disconnected (normal left inverted right x axis y axis)
> VGA-3-3 disconnected (normal left inverted right x axis y axis)
> VGA-2-2 disconnected (normal left inverted right x axis y axis)
> VGA-1-1 disconnected (normal left inverted right x axis y axis)
>
> …
>
> lspci -nnk | grep VGA
>
> 0001:05:00.0 VGA compatible controller [0300]: Matrox Electronics Systems Ltd. MGA G200 AGP [102b:0521] (rev 03)
>
> Thanks,
> Christian
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/mgag200/mgag200_mode.c?id=6cb31fba137d45e682ce455b8ea364f44d5d4f98

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)