Support for screens larger than 2048x2048

[jiridurdis]

Hi,

I believe that while Pi is suitable for video playback up to 1080p only, it still would be nice to support larger screens for other not-so-demanding scenarios. At the moment, maximal screen size is hardcoded to 2048x2048 in vc4_kms.c.

Pi is capable of 4K (3840x2160@25Hz) output over HDMI (using fbturbo and custom hdmi_cvt or hdmi_timings line in config.txt), which is totally OK for displaying dashboards, demos, slideshows etc.

[anholt]

Care to submit a tested patch to the dri-devel mailing list? I don't have 4k hw to test against.

[jiridurdis]

Hi,

Simple change of values in vc4_kms.c to 4096x4096 is not sufficient to make it work.

It allows me to create a new custom resolution using xrandr, but it fails when I try to apply it.
This works with 4096x4096 as new maximal screen size:

xrandr --newmode "3840x2160"  220.43  3840 3888 3920 4000  2160 2163 2168 2222 +hsync +vsync
xrandr --addmode HDMI-1 "3840x2160"

But this fails with error:

xrandr --output HDMI-1 --mode "3840x2160" --verbose

screen 0: 3840x2160 1013x570 mm  96.25dpi
crtc 2:  3840x2160_1  25.00 +0+0 "HDMI-1"
xrandr: Configure crtc 2 failed
crtc 0: disable
crtc 1: disable
crtc 2: disable
screen 0: revert
crtc 0: revert
crtc 1: revert
crtc 2: revert

This modeline is working for me with fbturbo_dev and increased hdmi_pixel_freq_limit.

Any idea on why this is failing?

[anholt]

We limit the pixel clock in vc4_hdmi_encoder_mode_valid() -- perhaps that is it? Enabling drm.debug can help see where things are failing (sudo zsh -c "echo 0x1e > /sys/module/drm/parameters/debug")

[jiridurdis]

That could be it, thank you for suggestion. Will try tomorrow.

[jiridurdis]

After increasing pixel clock limit, I can apply that modeline, but it crashes driver and X server with following output in dmesg:

[   33.581666] ------------[ cut here ]------------
[   33.581762] WARNING: CPU: 2 PID: 621 at drivers/gpu/drm/drm_atomic_helper.c:1240 drm_atomic_helper_wait_for_vblanks.part.0+0x260/0x26c [drm_kms_helper]
[   33.581766] [CRTC:67:crtc-2] vblank wait timed out
[   33.581769] Modules linked in: fuse rfcomm cmac bnep hci_uart btbcm serdev bluetooth ecdh_generic brcmfmac brcmutil cfg80211 rfkill snd_bcm2835(C) uio_pdrv_genirq uio i2c_dev ip_tables x_tables ipv6 overlay vc4 drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm snd_soc_core snd_compress snd_pcm_dmaengine snd_pcm snd_timer snd i2c_bcm2835 fixed
[   33.581860] CPU: 2 PID: 621 Comm: Xorg Tainted: G         C      4.14.70-v7 #1
[   33.581863] Hardware name: BCM2835
[   33.581883] [<8010fb70>] (unwind_backtrace) from [<8010bee8>] (show_stack+0x20/0x24)
[   33.581893] [<8010bee8>] (show_stack) from [<8076dbc0>] (dump_stack+0xc8/0x114)
[   33.581902] [<8076dbc0>] (dump_stack) from [<8011d464>] (__warn+0xe8/0x114)
[   33.581910] [<8011d464>] (__warn) from [<8011d4d8>] (warn_slowpath_fmt+0x48/0x50)
[   33.581977] [<8011d4d8>] (warn_slowpath_fmt) from [<7f162eac>] (drm_atomic_helper_wait_for_vblanks.part.0+0x260/0x26c [drm_kms_helper])
[   33.582107] [<7f162eac>] (drm_atomic_helper_wait_for_vblanks.part.0 [drm_kms_helper]) from [<7f162edc>] (drm_atomic_helper_wait_for_vblanks+0x24/0x28 [drm_kms_helper])
[   33.582210] [<7f162edc>] (drm_atomic_helper_wait_for_vblanks [drm_kms_helper]) from [<7f19ff14>] (vc4_atomic_complete_commit+0x88/0xd8 [vc4])
[   33.582283] [<7f19ff14>] (vc4_atomic_complete_commit [vc4]) from [<7f1a003c>] (vc4_atomic_commit+0xd8/0x124 [vc4])
[   33.582469] [<7f1a003c>] (vc4_atomic_commit [vc4]) from [<7f0cf740>] (drm_atomic_commit+0x5c/0x68 [drm])
[   33.582677] [<7f0cf740>] (drm_atomic_commit [drm]) from [<7f1639c4>] (drm_atomic_helper_set_config+0x94/0xb4 [drm_kms_helper])
[   33.582874] [<7f1639c4>] (drm_atomic_helper_set_config [drm_kms_helper]) from [<7f0c3598>] (__drm_mode_set_config_internal+0x68/0xec [drm])
[   33.583129] [<7f0c3598>] (__drm_mode_set_config_internal [drm]) from [<7f0c3edc>] (drm_mode_setcrtc+0x3a8/0x4f4 [drm])
[   33.583383] [<7f0c3edc>] (drm_mode_setcrtc [drm]) from [<7f0be7e8>] (drm_ioctl_kernel+0x78/0xb4 [drm])
[   33.583635] [<7f0be7e8>] (drm_ioctl_kernel [drm]) from [<7f0beb2c>] (drm_ioctl+0x194/0x34c [drm])
[   33.583770] [<7f0beb2c>] (drm_ioctl [drm]) from [<80296654>] (do_vfs_ioctl+0x9c/0x7c0)
[   33.583779] [<80296654>] (do_vfs_ioctl) from [<80296dbc>] (SyS_ioctl+0x44/0x6c)
[   33.583789] [<80296dbc>] (SyS_ioctl) from [<80107dc0>] (ret_fast_syscall+0x0/0x28)
[   33.583795] ---[ end trace ad75b12d34bcd044 ]---
[   43.993392] [drm:drm_atomic_helper_commit_cleanup_done [drm_kms_helper]] *ERROR* [CRTC:67:crtc-2] flip_done timed out
[   48.770042] vc4-drm soc:gpu: failed to allocate buffer with size 14680064

Last line with error about buffer allocation wasn't there after second attempt to apply that modeline, so it may not be related to this problem.

[lategoodbye]

@jiridurdis Looks like you are using the Foundation kernel, are you able to build a recent mainline version like 4.19-rc8 or at least 4.18?

[jiridurdis]

Still crashing on vanilla 4.18.14:

[  232.702997] ------------[ cut here ]------------
[  232.703084] WARNING: CPU: 3 PID: 8039 at drivers/gpu/drm/drm_atomic_helper.c:1362 drm_atomic_helper_wait_for_vblanks.part.1+0x23c/0x248 [drm_kms_helper]
[  232.703089] [CRTC:89:crtc-2] vblank wait timed out
[  232.703093] Modules linked in: cmac brcmfmac sha256_generic sha256_arm cfg80211 brcmutil crc32_arm_ce hci_uart btbcm bluetooth ecdh_generic bcm2835_thermal vc4 snd_soc_core ac97_bus snd_pcm_dmaengine snd_pcm snd_timer snd soundcore cec drm_kms_helper drm phy_generic
[  232.703184] CPU: 3 PID: 8039 Comm: Xorg Not tainted 4.18.14 #2
[  232.703188] Hardware name: BCM2835
[  232.703219] [<c0311b04>] (unwind_backtrace) from [<c030caec>] (show_stack+0x10/0x14)
[  232.703239] [<c030caec>] (show_stack) from [<c0cd622c>] (dump_stack+0x88/0xa4)
[  232.703257] [<c0cd622c>] (dump_stack) from [<c0344d20>] (__warn+0xe4/0x110)
[  232.703271] [<c0344d20>] (__warn) from [<c0344d84>] (warn_slowpath_fmt+0x38/0x48)
[  232.703330] [<c0344d84>] (warn_slowpath_fmt) from [<bf0802d4>] (drm_atomic_helper_wait_for_vblanks.part.1+0x23c/0x248 [drm_kms_helper])
[  232.703434] [<bf0802d4>] (drm_atomic_helper_wait_for_vblanks.part.1 [drm_kms_helper]) from [<bf14a4e4>] (vc4_atomic_complete_commit+0xac/0x350 [vc4])
[  232.703531] [<bf14a4e4>] (vc4_atomic_complete_commit [vc4]) from [<bf14a8b8>] (vc4_atomic_commit+0x130/0x160 [vc4])
[  232.703627] [<bf14a8b8>] (vc4_atomic_commit [vc4]) from [<bf080c78>] (drm_atomic_helper_set_config+0x6c/0x98 [drm_kms_helper])
[  232.703805] [<bf080c78>] (drm_atomic_helper_set_config [drm_kms_helper]) from [<bf011bf4>] (__drm_mode_set_config_internal+0x58/0xec [drm])
[  232.704033] [<bf011bf4>] (__drm_mode_set_config_internal [drm]) from [<bf012528>] (drm_mode_setcrtc+0x428/0x53c [drm])
[  232.704254] [<bf012528>] (drm_mode_setcrtc [drm]) from [<bf00d0f8>] (drm_ioctl_kernel+0x84/0xc0 [drm])
[  232.704473] [<bf00d0f8>] (drm_ioctl_kernel [drm]) from [<bf00d4ac>] (drm_ioctl+0x1d4/0x3c0 [drm])
[  232.704594] [<bf00d4ac>] (drm_ioctl [drm]) from [<c047780c>] (do_vfs_ioctl+0x88/0x8fc)
[  232.704608] [<c047780c>] (do_vfs_ioctl) from [<c04780b4>] (ksys_ioctl+0x34/0x5c)
[  232.704621] [<c04780b4>] (ksys_ioctl) from [<c0301000>] (ret_fast_syscall+0x0/0x54)
[  232.704628] Exception stack(0xd3969fa8 to 0xd3969ff0)
[  232.704639] 9fa0:                   b6fc0ce8 bef415a0 0000000c c06864a2 bef415a0 00000001
[  232.704651] 9fc0: b6fc0ce8 bef415a0 c06864a2 00000036 00be3e30 00000091 00000059 00000000
[  232.704659] 9fe0: b6dc708c bef41584 b6dae950 b6aab8ac
[  232.704668] ---[ end trace 675cb1b5b812c856 ]---
[  232.762986] ------------[ cut here ]------------
[  232.763068] WARNING: CPU: 3 PID: 8039 at drivers/gpu/drm/drm_atomic_helper.c:1362 drm_atomic_helper_wait_for_vblanks.part.1+0x23c/0x248 [drm_kms_helper]
[  232.763073] [CRTC:89:crtc-2] vblank wait timed out
[  232.763077] Modules linked in: cmac brcmfmac sha256_generic sha256_arm cfg80211 brcmutil crc32_arm_ce hci_uart btbcm bluetooth ecdh_generic bcm2835_thermal vc4 snd_soc_core ac97_bus snd_pcm_dmaengine snd_pcm snd_timer snd soundcore cec drm_kms_helper drm phy_generic
[  232.763169] CPU: 3 PID: 8039 Comm: Xorg Tainted: G        W         4.18.14 #2
[  232.763173] Hardware name: BCM2835
[  232.763204] [<c0311b04>] (unwind_backtrace) from [<c030caec>] (show_stack+0x10/0x14)
[  232.763222] [<c030caec>] (show_stack) from [<c0cd622c>] (dump_stack+0x88/0xa4)
[  232.763240] [<c0cd622c>] (dump_stack) from [<c0344d20>] (__warn+0xe4/0x110)
[  232.763254] [<c0344d20>] (__warn) from [<c0344d84>] (warn_slowpath_fmt+0x38/0x48)
[  232.763314] [<c0344d84>] (warn_slowpath_fmt) from [<bf0802d4>] (drm_atomic_helper_wait_for_vblanks.part.1+0x23c/0x248 [drm_kms_helper])
[  232.763417] [<bf0802d4>] (drm_atomic_helper_wait_for_vblanks.part.1 [drm_kms_helper]) from [<bf14a4e4>] (vc4_atomic_complete_commit+0xac/0x350 [vc4])
[  232.763506] [<bf14a4e4>] (vc4_atomic_complete_commit [vc4]) from [<bf14a8b8>] (vc4_atomic_commit+0x130/0x160 [vc4])
[  232.763674] [<bf14a8b8>] (vc4_atomic_commit [vc4]) from [<bf01e168>] (drm_atomic_connector_commit_dpms+0xe8/0xf8 [drm])
[  232.763905] [<bf01e168>] (drm_atomic_connector_commit_dpms [drm]) from [<bf023678>] (drm_mode_obj_set_property_ioctl+0x18c/0x284 [drm])
[  232.764133] [<bf023678>] (drm_mode_obj_set_property_ioctl [drm]) from [<bf022174>] (drm_mode_connector_property_set_ioctl+0x34/0x40 [drm])
[  232.764357] [<bf022174>] (drm_mode_connector_property_set_ioctl [drm]) from [<bf00d0f8>] (drm_ioctl_kernel+0x84/0xc0 [drm])
[  232.764576] [<bf00d0f8>] (drm_ioctl_kernel [drm]) from [<bf00d4ac>] (drm_ioctl+0x1d4/0x3c0 [drm])
[  232.764695] [<bf00d4ac>] (drm_ioctl [drm]) from [<c047780c>] (do_vfs_ioctl+0x88/0x8fc)
[  232.764708] [<c047780c>] (do_vfs_ioctl) from [<c04780b4>] (ksys_ioctl+0x34/0x5c)
[  232.764721] [<c04780b4>] (ksys_ioctl) from [<c0301000>] (ret_fast_syscall+0x0/0x54)
[  232.764728] Exception stack(0xd3969fa8 to 0xd3969ff0)
[  232.764738] 9fa0:                   00000000 bef415f0 0000000c c01064ab bef415f0 7aa1b400
[  232.764750] 9fc0: 00000000 bef415f0 c01064ab 00000036 0029bc9c 00be3e30 0023fa68 002403cc
[  232.764758] 9fe0: b6dc708c bef415d4 b6dae950 b6aab8ac
[  232.764766] ---[ end trace 675cb1b5b812c857 ]---

It does not work in 4.19-rc8 either, but it behaves differently. This is what I see during boot:

[  163.047446] ------------[ cut here ]------------
[  163.047534] WARNING: CPU: 0 PID: 5702 at drivers/gpu/drm/vc4/vc4_plane.c:631 vc4_plane_atomic_check+0xbc4/0xc30 [vc4]
[  163.047549] Modules linked in: cmac brcmfmac sha256_generic sha256_arm cfg80211 brcmutil crc32_arm_ce raspberrypi_hwmon hci_uart btbcm bluetooth ecdh_generic bcm2835_thermal overlay vc4 snd_soc_core ac97_bus snd_pcm_dmaengine snd_pcm snd_timer snd soundcore cec drm_kms_helper drm phy_generic
[  163.047669] CPU: 0 PID: 5702 Comm: Xorg Tainted: G        W         4.19.0-rc8 #7
[  163.047676] Hardware name: BCM2835
[  163.047730] [<c03117c4>] (unwind_backtrace) from [<c030c6d0>] (show_stack+0x10/0x14)
[  163.047770] [<c030c6d0>] (show_stack) from [<c0ceb5cc>] (dump_stack+0x88/0xa4)
[  163.047810] [<c0ceb5cc>] (dump_stack) from [<c0344ee8>] (__warn+0xe4/0x110)
[  163.047845] [<c0344ee8>] (__warn) from [<c0344fe0>] (warn_slowpath_null+0x3c/0x48)
[  163.047952] [<c0344fe0>] (warn_slowpath_null) from [<bf156ff8>] (vc4_plane_atomic_check+0xbc4/0xc30 [vc4])
[  163.048098] [<bf156ff8>] (vc4_plane_atomic_check [vc4]) from [<bf081e90>] (drm_atomic_helper_check_planes+0xc8/0x1c8 [drm_kms_helper])
[  163.048220] [<bf081e90>] (drm_atomic_helper_check_planes [drm_kms_helper]) from [<bf0856d8>] (drm_atomic_helper_check+0x30/0x88 [drm_kms_helper])
[  163.048573] [<bf0856d8>] (drm_atomic_helper_check [drm_kms_helper]) from [<bf01d294>] (drm_atomic_check_only+0x4a4/0x678 [drm])
[  163.048969] [<bf01d294>] (drm_atomic_check_only [drm]) from [<bf01d478>] (drm_atomic_commit+0x10/0x48 [drm])
[  163.049202] [<bf01d478>] (drm_atomic_commit [drm]) from [<bf087d24>] (restore_fbdev_mode_atomic+0x150/0x1ac [drm_kms_helper])
[  163.049352] [<bf087d24>] (restore_fbdev_mode_atomic [drm_kms_helper]) from [<bf08b2a4>] (drm_fb_helper_restore_fbdev_mode_unlocked+0x48/0x90 [drm_kms_helper])
[  163.049552] [<bf08b2a4>] (drm_fb_helper_restore_fbdev_mode_unlocked [drm_kms_helper]) from [<bf00bc6c>] (drm_lastclose+0x2c/0xcc [drm])
[  163.049829] [<bf00bc6c>] (drm_lastclose [drm]) from [<bf00bdac>] (drm_release+0xa0/0xd4 [drm])
[  163.049961] [<bf00bdac>] (drm_release [drm]) from [<c04689c4>] (__fput+0x88/0x1c4)
[  163.049983] [<c04689c4>] (__fput) from [<c03612b4>] (task_work_run+0xa8/0xcc)
[  163.050005] [<c03612b4>] (task_work_run) from [<c030bee0>] (do_work_pending+0xc4/0xcc)
[  163.050021] [<c030bee0>] (do_work_pending) from [<c030106c>] (slow_work_pending+0xc/0x20)
[  163.050027] Exception stack(0xd4077fb0 to 0xd4077ff8)
[  163.050038] 7fa0:                                     00000000 00000000 060e8000 060e8000
[  163.050050] 7fc0: 00000001 00244e60 00000000 00000006 00235028 00000000 00000001 00000001
[  163.050061] 7fe0: 00000000 bee16b2c b63cd288 b6b4944c 60000010 0000000b
[  163.050149] ---[ end trace 82f2c92fc673d152 ]---

No errors after activating modeline using xrandr, but still no output.

There is interesting difference in vcgencmd output:
With generic framebuffer configured with hdmi_timings in config.txt:

root@raspberrypi:~# vcgencmd measure_clock pixel
frequency(29)=220430000
root@raspberrypi:~# vcgencmd measure_clock hdmi
frequency(9)=299766000

With vc4, after applying modeline with xrandr:

root@raspberrypi:~# vcgencmd measure_clock pixel
frequency(29)=235000
root@raspberrypi:~# vcgencmd measure_clock hdmi
frequency(9)=249513000

HDMI clocks are very close to limits that i set in both cases. Pixel clock with framebuffer is equal to my hdmi_timings setting, but for vc4 that small value does not make sense to me.