6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Jan 07, 2022 5:11 pm

I think I've found the binding issue. It's actually registering the HDMI audio sound card that is reporting a -EPROBE_DEFER for reasons buried in the sound subsystem, but it's then never retried.
Using "dtoverlay=vc4-kms-v3d,noaudio" gets around that, although loses HDMI audio.

I've got other patches queued up so I'm also having to disable the touchscreen controller - "dtoverlay=vc4-kms-dsi-7inch,disable_touch=1". I believe that is going to be down to the touch controller powering things up when DSI isn't initialised. I thought I had that init sequence cracked, but apparently not.
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aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Jan 07, 2022 5:26 pm

6by9 wrote:
Fri Jan 07, 2022 5:11 pm
I think I've found the binding issue. It's actually registering the HDMI audio sound card that is reporting a -EPROBE_DEFER for reasons buried in the sound subsystem, but it's then never retried.
Using "dtoverlay=vc4-kms-v3d,noaudio" gets around that, although loses HDMI audio.

I've got other patches queued up so I'm also having to disable the touchscreen controller - "dtoverlay=vc4-kms-dsi-7inch,disable_touch=1". I believe that is going to be down to the touch controller powering things up when DSI isn't initialised. I thought I had that init sequence cracked, but apparently not.
do you have this in a github repro or can I simply add/change the overlay?
Though, I must check if I did not add the 'noaudio' option on that platform as I had issues with audio when working on the Innolux overlay (which then turned out I was simply using the wrong PWM module; anyhow I wanted to make sure nothing else tries to bind the PWMs).

Do I need to remove the auto-probing overlay for both touch and display or can they be there (as the addresses will not ack)?

6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Jan 07, 2022 5:43 pm

aBUGSworstnightmare wrote:
Fri Jan 07, 2022 5:26 pm
do you have this in a github repro or can I simply add/change the overlay?
Just change the lines in config.txt - those are standard options.

FWIW I have pushed my changes to https://github.com/6by9/linux/tree/rpi-5.15.y-dsi.
That has the conversion to DSI being a bridge, and I'd hope that adding in the SN65DSI83 overlay may just work as the driver is already in the tree. I'll try it with moving all the _enable logic into _pre_enable and setting the new DRM_BRIDGE_OP_UPSTREAM_FIRST flag too to hopefully correct the init phase.
aBUGSworstnightmare wrote:Though, I must check if I did not add the 'noaudio' option on that platform as I had issues with audio when working on the Innolux overlay (which then turned out I was simply using the wrong PWM module; anyhow I wanted to make sure nothing else tries to bind the PWMs).

Do I need to remove the auto-probing overlay for both touch and display or can they be there (as the addresses will not ack)?
I have set display_auto_detect=0 because I generally want to be in control of my dev platforms.
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6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Jan 07, 2022 6:05 pm

SN65DSI83 doesn't follow the behaviour documented in https://github.com/torvalds/linux/commi ... 09c5e9fafa, so attach never gets called and it all stalls. Those fixes appear to be in drm-misc (so heading for 5.17), and probably need cherry-picking.
https://cgit.freedesktop.org/drm/drm-mi ... n65dsi83.c
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6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Jan 07, 2022 6:37 pm

That was relatively straightforward.
rpi-5.15.y-dsi branch now updated with the cherry-picked commits (I should have added the upstream commit hashes - done), and is working fine on your 3 lane DSI83 board with 800x1280 panel. I haven't got HDMI connected at the same time, and I have had to disable HDMI audio, but otherwise it all seems good.

Maxime's not back at work yet, so I'll ask him on Monday about how the boot order/defer stuff should all work.
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aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Jan 07, 2022 6:57 pm

6by9 wrote:
Fri Jan 07, 2022 6:37 pm
That was relatively straightforward.
rpi-5.15.y-dsi branch now updated with the cherry-picked commits (I should have added the upstream commit hashes - done), and is working fine on your 3 lane DSI83 board with 800x1280 panel. I haven't got HDMI connected at the same time, and I have had to disable HDMI audio, but otherwise it all seems good.

Maxime's not back at work yet, so I'll ask him on Monday about how the boot order/defer stuff should all work.
wow..that was fast! Thanks for taking time for it.
Will pull that repro and test two modules that have nit been connected to the board yet: LG18.5in @ 1364x768 and a 23in FHD (also LG). Let's see if the FHD will do on 3 lanes.. (and or if 4 lanes will work now as I've not tested for this recently).

6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Jan 07, 2022 7:13 pm

aBUGSworstnightmare wrote:
Fri Jan 07, 2022 6:57 pm
wow..that was fast! Thanks for taking time for it.
Will pull that repro and test two modules that have nit been connected to the board yet: LG18.5in @ 1364x768 and a 23in FHD (also LG). Let's see if the FHD will do on 3 lanes.. (and or if 4 lanes will work now as I've not tested for this recently).
I'm still suspecting that the 3 vs 4 lane thing is down to the PLL config and there being no proper handling for burst mode. The DSI83 is set up based on the DSI timing which may be different from the desired LVDS timing. If the result is outside of what the panel is wanting, then it fails.
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aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Sat Jan 08, 2022 2:47 pm

pulled your repro, added the timing details of the LG 18.5in, changed the overlay and compiled the kernel.

One of my MIPI2LVDS boards is now running with 3lane DSI1 from the CM4 on kernel 5.15.13.

Using screen configuration editor for rotating the display is working, as now is recover from screen blanking!

Also tested with 4-lane DSI interface but that one fails - as you've expected already.

thmang82
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Tue Jan 18, 2022 10:14 pm

First of all, thanks for all the information in this post. It helped me a lot for making a custom carrier board with the DSI86 chip work (DSI to eDP).

I have one issue though: As soon as I configure my overlay for using 4 DSI lanes, the display will not work any more
With 3 lanes everything is working ok. I can drive two different 1920x1080 panels with up to 44 Hz.
More than 44Hz is not possible with 3 lanes, as the "integer-only DSI clock divider" situation will not allow for a higher DSI data rate.

I am on a 5.10.74 kernel with patches to simple-panel.c and ti-sn65dsi86.c. The bridge driver patched for lots of additional debug output lines.
When loading with an overlay with 4-lanes set, dmsg shows that the video driver is initialized seemingly ok. Link training works for example.
But in the end, there is no image shown. The only indication in my kernel debug output that something is wrong is an error bit in the 0xf6 status register of the bridge chip.

@6by9 and @aBUGSworstnightmare: have you been at any time able to drive a display via 4 DSI-lanes from DSI1?

44Hz are enough for my application, but still, out of curiosity, I am interested whats the culprint with using all 4 lanes.
I would like to understand if my board has an issue, or if this is a general issue of the CM4 or it's DSI kernel driver?
At some point I already suspected a routing length issue, as channel 4 of DSI1 is the only one that's located on the outer pin-row of the CM4 board-to-board connector. My differential pair-routing compensates for this (all pairs have same length between connector pins and bridge chip), but I suspected that maybe on the CM4 the pair is routed differently. But on the other hand, I suspect the Raspberry Pi guys know pretty well how to do such stuff. So maybe a vc4_dsi driver issue?

iocapa
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Jan 19, 2022 3:16 pm

have you been at any time able to drive a display via 4 DSI-lanes from DSI1?
I can confirm that DSI1 with 4 lanes worked in pre-mainline (Linux raspberrypi 5.10.0-rc6-v7l+ #1 SMP Wed Jan 13 13:34:46 EET 2021 armv7l GNU/Linux).

Managed to drive a 1600x1440 panel (~200K more pixels than a FHD panel) with well over 60 FPS, and it was actually weird because it looked like the interface supported rates way higher than the advertised 1Gb per lane.

I didn't go further with that project but you can find some posts here: viewtopic.php?t=299734

aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Jan 19, 2022 4:04 pm

thmang82 wrote:
Tue Jan 18, 2022 10:14 pm
..
I am on a 5.10.74 kernel with patches to simple-panel.c and ti-sn65dsi86.c. The bridge driver patched for lots of additional debug output lines.
When loading with an overlay with 4-lanes set, dmsg shows that the video driver is initialized seemingly ok. Link training works for example.
But in the end, there is no image shown. The only indication in my kernel debug output that something is wrong is an error bit in the 0xf6 status register of the bridge chip.

@6by9 and @aBUGSworstnightmare: have you been at any time able to drive a display via 4 DSI-lanes from DSI1?

44Hz are enough for my application, but still, out of curiosity, I am interested whats the culprint with using all 4 lanes.
I would like to understand if my board has an issue, or if this is a general issue of the CM4 or it's DSI kernel driver?
At some point I already suspected a routing length issue, as channel 4 of DSI1 is the only one that's located on the outer pin-row of the CM4 board-to-board connector. My differential pair-routing compensates for this (all pairs have same length between connector pins and bridge chip), but I suspected that maybe on the CM4 the pair is routed differently. But on the other hand, I suspect the Raspberry Pi guys know pretty well how to do such stuff. So maybe a vc4_dsi driver issue?
I've never managed to get 4-lanes running with the hardware I have here (DSI83 and DSI85 based, means DSI-to-LVDS).
But harlab gor a JDI panel running on 4-lanes https://github.com/harlab/CM4_LCD_LT070ME05000, and if memory serves me right Dave also got a MIPI-DSI panel running on all 4 lanes. As incapa also got a MIPI panel running on 4-lanes there still might be an issue for the DSI8x bridges.

For what it's with, maybe you want to use 5.15.13 kernel from Dave (6by9), add your patches (simple-panel and DSI86) and see if it makes any difference. https://github.com/6by9/linux/tree/rpi-5.15.y-dsi is the branch which I'm running on a DSI83 HW atm. With that one rotation/screen blanking etc is working flawlessly for the first time (when dealing with the DSI8x bridges).

I'm also interested in DSI86 as I have some nice eDP modules around which are 2560x1440pixels --> would like to try to get them running at single channel DSI (as that's the only option for using them with a Pi cause DSI0 is dual-lane only).

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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Jan 19, 2022 4:53 pm

1Gbit/s is the design spec of the block, but it may well run faster.
The bigger limitation is that it works off an integer divider, so the exact link speed for the next step up may be significant.

DSI83 claims to support DSI burst mode (which is effectively enforced on BCM283x by the DSI link speed not necessarily matching the desired LVDS speed), but the PLL is fairly coarse in settings. DRM doesn't handle separating DSI link frequency from pixel rate anyway (something I've been looking at).

DSI86 is likely to be the same, at least in what the current driver supports.

If people wish, I am prepared to compile a tree (eg easy to clone from Github, not a load of random extra patches) and see what our DSI analyser makes of it.
I have yet to find any conditions that indicate that the Pi isn't following what is being asked, nor violating the DSI spec, but I'm happy to investigate if we do find something wrong.
Sending DCS commands is something that seems to be a bit hit and miss at present, and I'm not sure why.
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6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Jan 19, 2022 5:17 pm

6by9 wrote:
Wed Jan 19, 2022 4:53 pm
DSI86 is likely to be the same, at least in what the current driver supports.
I slightly take it back.
DSI86 wants either an external refclk (12, 19.2, 26, 27, or 38.4MHz), or fixed DSI clock link frequencies with continuous clock (468, 384, 416, 486, or 460.8MHz). I haven't run the numbers, but I suspect you will have to use an external refclk, but otherwise it may well work.
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aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Jan 19, 2022 7:13 pm

I want to make a re-spin of my latest board revison - which has dual DSI option - as I want to use another PWM controller (will has to act as port expander as well), but as there is no way for sourcing the components (DSI85 as well as the PWM controller) this is on hold. Will also add footprints for an external clock in order to check if thaf solves the 4-lane issue.

And as I could not prove that the bridge will run on 4-lanes I did not spend time/money in the DSI86 bridge board.

Panel which I want to test with is a ultraslim 13.3in WQHD that came from Fujitsu Lifebook (but was also used with additional PCAP in HP notebooks)

aBUGSworstnightmare
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SN65DSI8x driver - further testing with dual-channel LVDS

Mon Jan 31, 2022 7:28 am

Further testing of the SN65DSI8x driver in 5.15 kernel, this time using a LG 23in Full-HD display.
Size matters sometimes ...
IMG_20220131_080923.jpg
23in FHD display sitting on an easel. USB hub is mounted to the base, RPI sits on a (removable) mounting base (will maybe use the screen with some AD board as monitor if needed). Panel runs from 3-lane DSI.
IMG_20220131_080923.jpg (102.7 KiB) Viewed 4441 times
IMG_20220131_081004.jpg
Rear view reveals: CM4 on CM4IO + MIPI2LVDS. everything is mounted on a removable base, powered by 12V. As the display BL is 48V a step-up driver was needed (module doesn't have integrated BL driver).
IMG_20220131_081004.jpg (106.29 KiB) Viewed 4441 times
IMG_20220131_081011.jpg
LG LM230WF3-SLD1 23in FHD TFT (used in some Dell monitors i.e.) connected to MIPI2LVDS
IMG_20220131_081011.jpg (83.14 KiB) Viewed 4441 times

aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Feb 09, 2022 10:09 am

@6by9: Have you tested the DSI8x bridge driver on the official 64-bit release by chance?

Code: Select all

pi@CM42GBNVME-64:~ $ uname -a
Linux CM42GBNVME-64 5.15.21-v8+ #1 SMP PREEMPT Wed Feb 9 08:27:10 CET 2022 aarch64 GNU/Linux
Not working here for me when compiling the official kernel.

Were still here

Code: Select all

pi@CM42GBNVME-64:~ $ dmesg | grep vc4
pi@CM42GBNVME-64:~ $ dmesg | grep err
[    0.000000] Machine model: Raspberry Pi Compute Module 4 Rev 1.0
[    0.000000] CPU features: detected: ARM errata 1165522, 1319367, or 1530923
[    0.000000] irq_brcmstb_l2: registered L2 intc (/soc/interrupt-controller@7ef00100, parent irq: 10)
[    0.116369] raspberrypi-firmware soc:firmware: Attached to firmware from 2022-02-04T12:05:40, variant start
[    0.120387] raspberrypi-firmware soc:firmware: Firmware hash is a26faf97e3bf76bcc23949d7cdab2f96f399a0c3
[    0.286652] kvm [1]: vgic interrupt IRQ9
[    1.404132] hub 2-0:1.0: config failed, hub doesn't have any ports! (err -19)
[    1.411821] sdhci: Copyright(c) Pierre Ossman
[    4.751874] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.raspberrypi,4-compute-module.bin failed with error -2
pi@CM42GBNVME-64:~ $ dmesg | grep dsi
[    0.099369] platform fe700000.dsi: Fixing up cyclic dependency with fe101000.cprman
[    4.826686] i2c 10-002c: Fixing up cyclic dependency with fe700000.dsi
pi@CM42GBNVME-64:~ $ 
so your changes - following viewtopic.php?t=305690&start=325#p1956528 - did not make into the kernel yet?

6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Feb 09, 2022 7:24 pm

aBUGSworstnightmare wrote:
Wed Feb 09, 2022 10:09 am
@6by9: Have you tested the DSI8x bridge driver on the official 64-bit release by chance?
Not at present.
My DSI changes have now been reworked and my rpi-5.15.y-dsi branch is the base. https://github.com/6by9/linux/tree/rpi-5.15.y-sn65dsi83 adds the same patches as I had before for SN65DI83 - they compile, but I haven't tested against hardware yet.
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aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Wed Feb 09, 2022 7:50 pm

6by9 wrote:
Wed Feb 09, 2022 7:24 pm
aBUGSworstnightmare wrote:
Wed Feb 09, 2022 10:09 am
@6by9: Have you tested the DSI8x bridge driver on the official 64-bit release by chance?
Not at present.
My DSI changes have now been reworked and my rpi-5.15.y-dsi branch is the base. https://github.com/6by9/linux/tree/rpi-5.15.y-sn65dsi83 adds the same patches as I had before for SN65DI83 - they compile, but I haven't tested against hardware yet.
can do that (with 23in FHD display) .. Will report back during the course of tomorrow.

Edit: started compiling it..

aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Thu Feb 10, 2022 9:18 am

Working on your 5.15.18 - 32-bit
2022-02-10-091305_1920x1080_scrot.jpg
2022-02-10-091305_1920x1080_scrot.jpg (88.5 KiB) Viewed 4179 times
IMG_20220210_091436.jpg
IMG_20220210_091436.jpg (136.29 KiB) Viewed 4179 times
Will now test on a 64-bit.

aBUGSworstnightmare
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Thu Feb 10, 2022 11:11 am

No luck on 64-bit!
That's what I see in the logs, checking for a few items.

Code: Select all

pi@CM42GBNVME-64:~ $ dmesg | grep vc4
pi@CM42GBNVME-64:~ $ dmesg | grep err
[    0.000000] Machine model: Raspberry Pi Compute Module 4 Rev 1.0
[    0.000000] CPU features: detected: ARM errata 1165522, 1319367, or 1530923
[    0.000000] irq_brcmstb_l2: registered L2 intc (/soc/interrupt-controller@7ef00100, parent irq: 10)
[    0.116372] raspberrypi-firmware soc:firmware: Attached to firmware from 2022-02-04T12:05:40, variant start
[    0.120392] raspberrypi-firmware soc:firmware: Firmware hash is a26faf97e3bf76bcc23949d7cdab2f96f399a0c3
[    0.277377] kvm [1]: vgic interrupt IRQ9
[    1.400063] hub 2-0:1.0: config failed, hub doesn't have any ports! (err -19)
[    1.407760] sdhci: Copyright(c) Pierre Ossman
[    5.066714] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.raspberrypi,4-compute-module.bin failed with error -2
pi@CM42GBNVME-64:~ $ dmesg | grep dsi
[    0.099116] platform fe700000.dsi: Fixing up cyclic dependency with fe101000.cprman
[    5.291857] i2c 10-002c: Fixing up cyclic dependency with fe700000.dsi
pi@CM42GBNVME-64:~ $ uname -a
Linux CM42GBNVME-64 5.15.18-v8+ #1 SMP PREEMPT Thu Feb 10 10:33:56 CET 2022 aarch64 GNU/Linux
pi@CM42GBNVME-64:~ $ 
Strange to see this cyclic dependency appearing on 64-bit, but 'solved' on 32-bit.
Is there some fix missing which is available in 5.15.21 already (as that's the 'existing' kernel version on this DUT where I've compiled your repro just now).

Code: Select all

sudo nano /proc/device-tree/chosen/user-warnings

gives me nothing and - based on this viewtopic.php?t=329310#p1971069 - is the only possible solution atm for getting DT related info (most likely warnings only).

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Re: Rpi 4 with DRM and 7inch panel using kms driver

Thu Feb 10, 2022 12:07 pm

"Fixing up cyclic dependency with xx" appears to be a quirk since 5.12 and https://github.com/torvalds/linux/commi ... fd44e73955.
It's going to affect all CSI and DSI displays where CSI has to reference the source, and source reference CSI, and DSI has to reference the panel/bridge, and the panel/bridge references DSI.

I'm just compiling a 64bit kernel but will be testing against a 32bit userspace (it should make no difference as this is totally within the kernel). I'd suspect that some module isn't available rather than anything fundamental.
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6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Thu Feb 10, 2022 4:24 pm

6by9 wrote:
Thu Feb 10, 2022 12:07 pm
"Fixing up cyclic dependency with xx" appears to be a quirk since 5.12 and https://github.com/torvalds/linux/commi ... fd44e73955.
It's going to affect all CSI and DSI displays where CSI has to reference the source, and source reference CSI, and DSI has to reference the panel/bridge, and the panel/bridge references DSI.

I'm just compiling a 64bit kernel but will be testing against a 32bit userspace (it should make no difference as this is totally within the kernel). I'd suspect that some module isn't available rather than anything fundamental.
I've just built that kernel tree (rebased to 5.15.21) for v8, and the SN65DSI83 and display have come up fine. I haven't got a full 64bit OS image on a CM4 at present so can't test that, but I don't see there being a significant difference from userspace.

Ah, there does seem to be an issue if powered down and back up (eg due to rotating with xrandr). I'm checking to see if 32bit also has the same issue.
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6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Thu Feb 10, 2022 4:36 pm

6by9 wrote:
Thu Feb 10, 2022 4:24 pm
Ah, there does seem to be an issue if powered down and back up (eg due to rotating with xrandr). I'm checking to see if 32bit also has the same issue.
Yes, 32bit kernels appear to be affected too. I'll have to test the Pi panel tomorrow.
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6by9
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Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Feb 11, 2022 11:13 am

6by9 wrote:
Thu Feb 10, 2022 4:36 pm
6by9 wrote:
Thu Feb 10, 2022 4:24 pm
Ah, there does seem to be an issue if powered down and back up (eg due to rotating with xrandr). I'm checking to see if 32bit also has the same issue.
Yes, 32bit kernels appear to be affected too. I'll have to test the Pi panel tomorrow.
Shucks, Pi panel affected too - it doesn't reset properly if you disable and re-enable the display. More work required on the driver.
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aBUGSworstnightmare
Posts: 6106
Joined: Tue Jun 30, 2015 1:35 pm

Re: Rpi 4 with DRM and 7inch panel using kms driver

Fri Feb 11, 2022 11:30 am

6by9 wrote:
Fri Feb 11, 2022 11:13 am
6by9 wrote:
Thu Feb 10, 2022 4:36 pm
6by9 wrote:
Thu Feb 10, 2022 4:24 pm
Ah, there does seem to be an issue if powered down and back up (eg due to rotating with xrandr). I'm checking to see if 32bit also has the same issue.
Yes, 32bit kernels appear to be affected too. I'll have to test the Pi panel tomorrow.
Shucks, Pi panel affected too - it doesn't reset properly if you disable and re-enable the display. More work required on the driver.
Give me a hands-up when you're done and I will test on my hardware.

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