DRM fixes for cropping P030/SAND128 on Pi5

[6by9]

Addresses 2 of the glitches seen with zooming 10bit HEVC under Kodi.

Diagonal corruption when overlaying GUI with 10bit HEVC, or flickering for 8bit HEVC is still being investigated.

[6by9]

Diagonal corruption is something else, and not apparently related to background fill (tested by permanently enabling it). Suspect it is system load, but it is weird that it is only when updating the GUI layer that it causes problems.
Solving that one will have to wait.

[HiassofT]

In the initial version of this PR the Interstellar trailer worked fine on all zoom levels, on a 1920x1080p60 display, with the recent however the "blank screen" issue at zoom level 1.11 is back (as before the change).

Here's kmsprint output with zoom level 1.11 and display blanking out:

rpi5:~ # kmsprint 
Connector 0 (33) HDMI-A-1 (connected)
  Encoder 0 (32) TMDS
    Crtc 2 (92) 1920x1080@60.00 148.500 1920/88/44/148/+ 1080/4/5/36/+ 60 (60.00) D 
      Plane 2 (81) fb-id: 684 (crtcs: 2) 0,0 3840x1608 -> -106,94 2132x894 (XR24 AR24 AB24 XB24 RG16 BG16 AR15 XR15 RG24 BG24 YU16 YV16 YU24 YV24 YU12 YV12 NV12 NV21 NV16 NV61 P030 XR30 AR30 AB30 XB30 RGB8 BGR8 XR12 AR12 XB12 AB12 BX12 BA12 RX12 RA12)
        FB 684 0x0 (�j�
      Plane 4 (105) fb-id: 681 (crtcs: 1 2 3) 0,0 1920x1080 -> 0,0 1920x1080 (XR24 AR24 AB24 XB24 RG16 BG16 AR15 XR15 RG24 BG24 YU16 YV16 YU24 YV24 YU12 YV12 NV12 NV21 NV16 NV61 P030 XR30 AR30 AB30 XB30 RGB8 BGR8 XR12 AR12 XB12 AB12 BX12 BA12 RX12 RA12)
        FB 681 1920x1080 AR24
Connector 1 (42) HDMI-A-2 (disconnected)
  Encoder 1 (41) TMDS

[6by9]

Which version of the Interstellar trailer is it? 4k 10bit HEVC being downscaled to 1080p60?

[HiassofT]

The trailer is 4k HEVC 8bit. I'm using a 1920x1200 monitor here on my test setup, kodi GUI resolution set to 1920x1080p60 which is also used while playing this sample (the monitor doesn't support 24p)

$ ls -l Interstellar-divx-hevc-uhd-51ch-4K.mkv 
-rwxrw-r-- 2 hias hias 403766800 Jun 18  2019 Interstellar-divx-hevc-uhd-51ch-4K.mkv
$ md5sum Interstellar-divx-hevc-uhd-51ch-4K.mkv 
ad611d6067ff79b5b45bd3c571859c23  Interstellar-divx-hevc-uhd-51ch-4K.mkv
$ mediainfo Interstellar-divx-hevc-uhd-51ch-4K.mkv 
General
Unique ID                                : 86748321257335288719775507338167402396 (0x41431E73BC456F9EC4B2746B21093F9C)
Complete name                            : Interstellar-divx-hevc-uhd-51ch-4K.mkv
Format                                   : Matroska
Format version                           : Version 1
File size                                : 385 MiB
Duration                                 : 2 min 24 s
Overall bit rate                         : 22.3 Mb/s
Frame rate                               : 24.000 FPS
Writing application                      : DivXMKVMux 9.9.12.5441
Writing library                          : libDivXMediaFormat 4.0.0.0578

Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main@L5.1@Main
Codec ID                                 : V_MPEGH/ISO/HEVC
Duration                                 : 2 min 24 s
Bit rate                                 : 21.2 Mb/s
Width                                    : 3 840 pixels
Height                                   : 1 608 pixels
Display aspect ratio                     : 2.40:1
Frame rate mode                          : Constant
Frame rate                               : 24.000 FPS
Standard                                 : Component
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Bits/(Pixel*Frame)                       : 0.143
Stream size                              : 366 MiB (95%)
Language                                 : English
Default                                  : Yes
Forced                                   : No
Color range                              : Full

Audio
ID                                       : 2
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Commercial name                          : Dolby Digital
Codec ID                                 : A_AC3
Duration                                 : 2 min 24 s
Bit rate mode                            : Constant
Bit rate                                 : 640 kb/s
Channel(s)                               : 6 channels
Channel layout                           : L R C LFE Ls Rs
Sampling rate                            : 48.0 kHz
Frame rate                               : 31.250 FPS (1536 SPF)
Bit depth                                : 16 bits
Compression mode                         : Lossy
Stream size                              : 11.0 MiB (3%)
Language                                 : English
Service kind                             : Complete Main
Default                                  : Yes
Forced                                   : No

[6by9]

Thanks. I hadn't seen a failure at all with 8bit content, but that does seem to provoke one.

Increasing fetch_count by one for 8bit (x_offset & 31) == 30 covers some situations, but there's another case that is still failing at x1.58, which because it is 4k being scaled to 1080p is a greater crop/scale than all my 4k on 4k tests.

[6by9]

I've found the actual cause.

https://github.com/raspberrypi/linux/blob/rpi-6.12.y/drivers/gpu/drm/vc4/vc4_plane.c#L2016-L2032 increases the source size if fractionally cropping a pixel at the edge. There are conditions for SAND where that will require an extra word to be fetched, however fetch_count had already been computed. Fetching insufficient words results in a total stall.

[popcornmix]

Nice this feels more satisfactory that previous version.

[HiassofT]

Thanks a lot, testing with your latest update looks good here 👍