Intel UHD resolutions

[Randy Dunlap]

Hi,

I would like to use QHD resolution (2560x1440) with my shiny new
computer and display. That resolution works if I boot Windows 10
(cough).

What do I need to do to use that resolution in Linux?

I first tried openSUSE 15.3 (kernel 5.3.18-59.19-default)
then I build a v5.14 kernel and tried that.
Both of them max out at FHD (1920x1080).

I am booting with "i915.force_probe=4c8a" on the kernel command line.

My desktop is XFCE4.

CPU is:
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 167
model name	: 11th Gen Intel(R) Core(TM) i9-11900 @ 2.50GHz
stepping	: 1
microcode	: 0x40
cpu MHz		: 1021.742
cache size	: 16384 KB
physical id	: 0
siblings	: 16

with an H470 chipset. (ASRock DeskMini H470)

00:02.0 VGA compatible controller: Intel Corporation RocketLake-S GT1 [UHD Graphics 750] (rev 04)

or verbose:

00:02.0 VGA compatible controller: Intel Corporation RocketLake-S GT1 [UHD Graphics 750] (rev 04) (prog-if 00 [VGA controller])
	Subsystem: ASRock Incorporation Device 4c8a
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 153
	Region 0: Memory at b0000000 (64-bit, non-prefetchable) [size=16M]
	Region 2: Memory at a0000000 (64-bit, prefetchable) [size=256M]
	Region 4: I/O ports at 3000 [size=64]
	[virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: [40] Vendor Specific Information: Len=0c <?>
	Capabilities: [70] Express (v2) Root Complex Integrated Endpoint, MSI 00
		DevCap:	MaxPayload 128 bytes, PhantFunc 0
			ExtTag- RBE+
		DevCtl:	Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
			RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
			MaxPayload 128 bytes, MaxReadReq 128 bytes
		DevSta:	CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
		DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, O
BFF Not Supported
			 AtomicOpsCap: 32bit- 64bit- 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
			 AtomicOpsCtl: ReqEn-
	Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable+ 64bit-
		Address: fee00018  Data: 0000
		Masking: 00000000  Pending: 00000000
	Capabilities: [d0] Power Management version 2
		Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot
-,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [100 v1] Process Address Space ID (PASID)
		PASIDCap: Exec- Priv-, Max PASID Width: 14
		PASIDCtl: Enable- Exec- Priv-
	Capabilities: [200 v1] Address Translation Service (ATS)
		ATSCap:	Invalidate Queue Depth: 00
		ATSCtl:	Enable-, Smallest Translation Unit: 00
	Capabilities: [300 v1] Page Request Interface (PRI)
		PRICtl: Enable- Reset-
		PRISta: RF- UPRGI- Stopped+
		Page Request Capacity: 00008000, Page Request Allocation: 00000000
	Kernel driver in use: i915
	Kernel modules: i915


thanks.
-- 
~Randy