Due to recent commit a5b2781dcab2c77979a4b8adda781d2543580901 , I'm facing an issue where the backlight is dimmer than before in comparison to the backlight pre-commit on my Thinkpad W530.
Downgrading to an older kernel version fixes the issue.
I also realise that this recent commit replaces the intel_backlight folder in /sys/class/backlight with acpi_video0. It is also worth mentioning that I'm using Nouveau on my W530. Below are the screenshots highlighting the issue.
Kernel 6.1.22 with 10% brightness - https://i.imgur.com/7znm7xg.jpg Kernel 6.1.22 with 35% brightness and grub parameter acpi_backlight=video manually set - https://i.imgur.com/nD9O7pD.jpg
On Mon, Apr 17, 2023 at 10:18:32PM +0530, Русев Путин wrote:
Due to recent commit a5b2781dcab2c77979a4b8adda781d2543580901 , I'm facing an issue where the backlight is dimmer than before in comparison to the backlight pre-commit on my Thinkpad W530.
Any reason why you didn't cc: the developers of that commit?
Downgrading to an older kernel version fixes the issue.
I also realise that this recent commit replaces the intel_backlight folder in /sys/class/backlight with acpi_video0.
That's what this commit does, right?
Do you also have this issue on the latest 6.3-rc release?
thanks, greg k-h
Any reason why you didn't cc: the developers of that commit?
Sorry I did not realise I should have done that.
Do you also have this issue on the latest 6.3-rc release?
Yes I have tested it recently by installing the latest 6.3-rc7 kernel , and I do encounter the same issue there. I have linked the screenshots below referring the same. Kernel 6.3.0-rc7 with 43% brightness - https://i.imgur.com/5LqsEJb.jpg
That's what this commit does, right?
According to the commit , it was pushed to fix backlight controls which were broken on Lenovo Thinkpad W530 while using NVIDIA. It was not intended to reduce the backlight intensity on W530. Backlight is dimmer than before even when using the laptop in Intel iGPU mode.
Thanks
CC: Hans
On Thu, Apr 20, 2023 at 6:38 PM Русев Путин rockeraliexpress@gmail.com wrote:
Any reason why you didn't cc: the developers of that commit?
Sorry I did not realise I should have done that.
Do you also have this issue on the latest 6.3-rc release?
Yes I have tested it recently by installing the latest 6.3-rc7 kernel , and I do encounter the same issue there. I have linked the screenshots below referring the same. Kernel 6.3.0-rc7 with 43% brightness - https://i.imgur.com/5LqsEJb.jpg
That's what this commit does, right?
According to the commit , it was pushed to fix backlight controls which were broken on Lenovo Thinkpad W530 while using NVIDIA. It was not intended to reduce the backlight intensity on W530. Backlight is dimmer than before even when using the laptop in Intel iGPU mode.
Thanks
Hi Русев Путин,
On 4/20/23 19:02, Rafael J. Wysocki wrote:
CC: Hans
On Thu, Apr 20, 2023 at 6:38 PM Русев Путин rockeraliexpress@gmail.com wrote:
Any reason why you didn't cc: the developers of that commit?
Sorry I did not realise I should have done that.
Do you also have this issue on the latest 6.3-rc release?
Yes I have tested it recently by installing the latest 6.3-rc7 kernel , and I do encounter the same issue there. I have linked the screenshots below referring the same. Kernel 6.3.0-rc7 with 43% brightness - https://i.imgur.com/5LqsEJb.jpg
That's what this commit does, right?
According to the commit , it was pushed to fix backlight controls which were broken on Lenovo Thinkpad W530 while using NVIDIA. It was not intended to reduce the backlight intensity on W530. Backlight is dimmer than before even when using the laptop in Intel iGPU mode.
This patch should not change the maximum brightness. But you may need to adjust the brightness once after changing to a new kernel with the patch because the range / brightness-curve may be different.
On the imgur URL your display brightness shows as being at 43%, what happens if you use e.g. Fn + F9 to increase the brightness ?
I would expect you to be able to get back your old brightness level then and this should persist over reboots after you have adjusted it once.
If adjusting it does not help / work then we will need to revert the patch causing this.
Regards,
Hans
This patch should not change the maximum brightness. But you may need
to adjust the brightness once after changing to a new kernel with the patch because the range / brightness-curve may be different.
This patch does change the display brightness curve but it is very buggy and does not change the brightness as soon as set. There is a very significant delay in brightness transition on the laptop due to this patch. Also it is worth mentioning that this patch also messes up color contrast of the display causing significantly deeper blacks on the display.
I would expect you to be able to get back your old brightness level
then and this should persist over reboots after you have adjusted it once.
what happens if you use e.g. Fn + F9 to increase the brightness
Here are the attached pictures explaining the situation. 100% brightness on Kernel 6.3-rc7 - https://i.imgur.com/eQK890s.jpg 100% brightness on Kernel 6.1.22 - https://i.imgur.com/1rgNtxJ.jpg
Thanks.
On Fri, Apr 21, 2023 at 12:05 AM Hans de Goede hdegoede@redhat.com wrote:
Hi Русев Путин,
On 4/20/23 19:02, Rafael J. Wysocki wrote:
CC: Hans
On Thu, Apr 20, 2023 at 6:38 PM Русев Путин rockeraliexpress@gmail.com wrote:
Any reason why you didn't cc: the developers of that commit?
Sorry I did not realise I should have done that.
Do you also have this issue on the latest 6.3-rc release?
Yes I have tested it recently by installing the latest 6.3-rc7 kernel , and I do encounter the same issue there. I have linked the screenshots below referring the same. Kernel 6.3.0-rc7 with 43% brightness - https://i.imgur.com/5LqsEJb.jpg
That's what this commit does, right?
According to the commit , it was pushed to fix backlight controls which were broken on Lenovo Thinkpad W530 while using NVIDIA. It was not intended to reduce the backlight intensity on W530. Backlight is dimmer than before even when using the laptop in Intel iGPU mode.
This patch should not change the maximum brightness. But you may need to adjust the brightness once after changing to a new kernel with the patch because the range / brightness-curve may be different.
On the imgur URL your display brightness shows as being at 43%, what happens if you use e.g. Fn + F9 to increase the brightness ?
I would expect you to be able to get back your old brightness level then and this should persist over reboots after you have adjusted it once.
If adjusting it does not help / work then we will need to revert the patch causing this.
Regards,
Hans
Hi Русев,
On 4/27/23 17:35, Русев Путин wrote:
This patch should not change the maximum brightness. But you may need
to adjust the brightness once after changing to a new kernel with the patch because the range / brightness-curve may be different.
This patch does change the display brightness curve but it is very buggy and does not change the brightness as soon as set. There is a very significant delay in brightness transition on the laptop due to this patch. Also it is worth mentioning that this patch also messes up color contrast of the display causing significantly deeper blacks on the display.
Ok, lets remove the acpi_backlight=video quirk for Lenovo ThinkPad W530 then. This was intended to make life easier for Nvidia binary driver users, but since it is causing issues elsewhere Nvidia binary driver users will just have to manually pass acpi_backlight=video on the kernel commandline until Nvidia fixes the driver.
I'll submit a patch to remove the quirk right away.
Regards,
Hans
Hi Русев,
On 4/28/23 15:22, Hans de Goede wrote:
Hi Русев,
On 4/27/23 17:35, Русев Путин wrote:
This patch should not change the maximum brightness. But you may need
to adjust the brightness once after changing to a new kernel with the patch because the range / brightness-curve may be different.
This patch does change the display brightness curve but it is very buggy and does not change the brightness as soon as set. There is a very significant delay in brightness transition on the laptop due to this patch. Also it is worth mentioning that this patch also messes up color contrast of the display causing significantly deeper blacks on the display.
Ok, lets remove the acpi_backlight=video quirk for Lenovo ThinkPad W530 then. This was intended to make life easier for Nvidia binary driver users, but since it is causing issues elsewhere Nvidia binary driver users will just have to manually pass acpi_backlight=video on the kernel commandline until Nvidia fixes the driver.
I'll submit a patch to remove the quirk right away.
p.s.
In the mean time you can work around the regression by passing: "acpi_backlight=native" on the kernel commandline.
Regards,
Hans
linux-stable-mirror@lists.linaro.org
-
Greg KH -
Hans de Goede -
Rafael J. Wysocki -
Русев Путин