| Summary: | Intel_backlight fails to change eDP1 brightness on Dell Precision 5540 (Coffeelake) | ||||||
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| Product: | DRI | Reporter: | Arcadiy Ivanov <arcadiy> | ||||
| Component: | DRM/Intel | Assignee: | Intel GFX Bugs mailing list <intel-gfx-bugs> | ||||
| Status: | RESOLVED INVALID | QA Contact: | Intel GFX Bugs mailing list <intel-gfx-bugs> | ||||
| Severity: | major | ||||||
| Priority: | high | CC: | intel-gfx-bugs, jani.nikula, kai.heng.feng | ||||
| Version: | DRI git | ||||||
| Hardware: | x86-64 (AMD64) | ||||||
| OS: | Linux (All) | ||||||
| Whiteboard: | ReadyForDev, Triaged | ||||||
| i915 platform: | CFL | i915 features: | display/backlight | ||||
| Attachments: |
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Description
Arcadiy Ivanov
2019-07-23 17:08:28 UTC
Created attachment 144858 [details]
debug dmesg of drm-tip 2019y-07m-23d-12h-27m-47s UTC
Related bugs are: https://bugs.freedesktop.org/show_bug.cgi?id=111179 https://bugs.freedesktop.org/show_bug.cgi?id=111195 The SSD was was transferred from Skylake Dell Precision 7510 where backlight worked properly. > [ 6.495549] [drm:intel_dp_aux_enable_backlight [i915]] VBT defined backlight frequency 200 Hz
> [ 6.496173] [drm:intel_dp_aux_enable_backlight [i915]] VBT defined backlight frequency out of range
Could the "out of range" be the culprit? I would think that a thing like that should not be a debug log message but rather an error/warning.
I saw [Regression] on the title. If it's a regression please perform a kernel bisection. I put a "regression" in the title, because I took an SSD from Dell Precision 7510, put it in Dell Precision 5540 and observed that backlight stopped working - i.e. something that was working stopped. There is nothing to bisect, because the loss of functionality occurred with device upgrade, not kernel version upgrade. Also, this is Fedora 30, not Ubuntu. (In reply to Arcadiy Ivanov from comment #5) > I put a "regression" in the title, because I took an SSD from Dell Precision > 7510, put it in Dell Precision 5540 and observed that backlight stopped > working - i.e. something that was working stopped. There is nothing to > bisect, because the loss of functionality occurred with device upgrade, not > kernel version upgrade. > > Also, this is Fedora 30, not Ubuntu. Acradiy, Regression gives an impression that the issue has come up after upgrading the kernel, which is not in this case. So, I would like to remove that from the title. Btw, before setting up the SSD to Dell Precision 5540 machine(CFL), have you noticed this issue on CFL? Nope, I haven't. I could disable `i915.enable_dpcd_backlight=1` if you'd like to try, and let you know if it helps things. Sorry, this machine is a primary workhorse, I just can't yank the drive back and forth. I can confirm that removing `i915.enable_dpcd_backlight=1` fixes the brightness issue. @Jani, any comments here? (In reply to Arcadiy Ivanov from comment #8) > I can confirm that removing `i915.enable_dpcd_backlight=1` fixes the > brightness issue. Not a bug then. Displays have different ways of controlling the brightness, and you can't assume they are all the same. Ha! Sorry, it is a bug, reopening. The reason I had the `enable_dpcd_backlight=1` on in the first place was because without it external monitors failed to go to "energy saving" mode without it. Removing it causes eDP1 on 5540 brightness to be controllable but external monitors (via TB hub) apparently failed to go to sleep.
So:
enable_dpcd_backlight=1:
7510:
eDP1 - brightness controllable, energy savings mode works
external - N/A, energy savings mode works
5540:
eDP1 - brightness NOT controllable, energy savings mode works
external - N/A, energy savings mode works
enable_dpcd_backlight=0:
7510:
eDP1 - brightness controllable, energy savings mode works
external - N/A, energy savings mode DOES NOT work
5540:
eDP1 - brightness controllable, energy savings mode works
external - N/A, energy savings DOES NOT mode works
Please file a bug about the issue you experience then, not about backlight control. There is no issue with backlight if you remove the module parameter that is wrong for your platform. Apologies if that came out rude; everyone looking at this bug would think this is about backlight, which it was initially, and that was resolved. So please let's investigate the energy saving issue you apparently already had with your 7510 machine in a different bug. Please also drop the other parameters; I don't know what you try to achieve with: i915.enable_dc=2 i915.disable_power_well=0 i915.enable_fbc=1 i915.enable_dpcd_backlight=1 acpi_osi=Linux-Dell-Video Usually none of them should be required, and indeed setting some of the i915 parameters is strictly not supported by upstream. They are for debug purposes only. Finally, please don't add logs as comments. Please attach them. |
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