Scaling doesn't work with radeon. Screen rotation does work, though.
On a laptop with intel driver, the following works fine, except the mouse pointer is confined to the mode area, but I believe that is a known xorg-server bug to which a patch is available in bug #39949:
xrandr --fb 1920x1080 --output eDP1 --mode 1600x900 --scale-from 1920x1080
The same command, adapted to the radeon output device doesn't work. Same software configuration (xorg-184.108.40.2063, libdrm-git, mesa-git, xf86-video-ati-git, various kernel versions (at the moment 3.15.2)).
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cayman PRO [Radeon HD 6950] (prog-if 00 [VGA controller])
Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Device 0b00
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 41
Region 0: Memory at e0000000 (64-bit, prefetchable) [size=256M]
Region 2: Memory at f7e20000 (64-bit, non-prefetchable) [size=128K]
Region 4: I/O ports at e000 [size=256]
Expansion ROM at f7e00000 [disabled] [size=128K]
Capabilities:  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-
Capabilities:  Express (v2) Legacy Endpoint, MSI 00
DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <4us, L1 unlimited
ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
MaxPayload 128 bytes, MaxReadReq 512 bytes
DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr- TransPend-
LnkCap: Port #0, Speed 5GT/s, Width x16, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
ClockPM- Surprise- LLActRep- BwNot-
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, OBFF Not Supported
DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
Compliance De-emphasis: -6dB
LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete-, EqualizationPhase1-
EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest-
Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
Address: 00000000fee0100c Data: 4191
Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
Capabilities: [150 v1] Advanced Error Reporting
UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
UESvrt: DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
AERCap: First Error Pointer: 00, GenCap+ CGenEn- ChkCap+ ChkEn-
Kernel driver in use: radeon
Is scaling not implemented in radeon?
I'm not sure if EXA supports those options. You might try glamor.
No, it doesn't work with glamor either. Besides, I'd like to use EXA because of xv support.
Actually, I notice one difference after executing
xrandr --fb 1920x2400 --output HDMI-0 --mode 1920x1200 --scale-from 1920x2400
The vertical panel seems to stretch/extend to the new vertical size (2400). However, the intended scaling doesn't get applied.
xrandr --verbose before and after this command shows no differences.
Created attachment 102098 [details]
xrandr --verbose output after applying above xrandr command
(In reply to comment #2)
> No, it doesn't work with glamor either. Besides, I'd like to use EXA because
> of xv support.
glamor supports Xv as well.
Maybe I forgot to compile in support for xv then. One way or the other, scaling doesn't work.
I'm running into the same problem. The transform matrix doesn't seem to get updated at all.
Author: Michel Dänzer <firstname.lastname@example.org>
Date: Fri Jan 15 16:48:46 2016 +0900
Fix RandR CRTC transforms
Currently, Xorg will only transform the cursor as of the first time the
cursor image changes after a transform is set.
Thanks for fixing it. Unfortunately, it comes too bit late, and I can no longer test this because my old graphics card went to the gpu nirvana :-(
That said, hopefully it helps Sebastian and other users.
It's working. Thanks, Michel!
*** Bug 31799 has been marked as a duplicate of this bug. ***