Issue or bug concerning DRRS on old i7-4980HQ

[René Herman]

Here's that Ubuntu launchpad bug on freedesktop.org, but including a 
possibly interesting fix from 5 months ago in the currently last comment:

https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/3441

When Windows 10 goes out of support I expect a fair few of these older 
systems (supposedly without TPM) will get Linufied.

Regards,
Rene

On 31-07-2025 04:49, René Herman wrote:

> Hello all.
> 
> Addresses as per MANTAINERS, and Ville as per Git history...
> 
> I've been trying to assist a new Linux user with an old 2015 Alienware 
> 17 R2, i7-4980HQ (Iris Pro 5200) together with NVIDIA GTX980M.
> 
> The user experienced flickering (in a brightness sense) and had traced 
> this back to Intel DRRS. I supplied a simple test patch as
> 
> --- linux-6.8.0/drivers/gpu/drm/i915/display/intel_dp.c.orig
> +++ linux-6.8.0/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -2727,6 +2727,8 @@
>   {
>       struct drm_i915_private *i915 = to_i915(connector->base.dev);
> 
> +    return false;
> +
>       if (pipe_config->vrr.enable)
>           return false;
> 
> which does indeed work. Set out to then solve it right(er) and ran into 
> the debugfs drrs ctl file, for him
> 
> /sys/kernel/debug/dri/1/crtc-0/i915_drrs_ctl
> 
> We haven't however been able to do anything useful with that. If we echo 
> 0 into it it seems that DRRS does temporarily go to "DRRS active: no" in 
> the corresponding i915_drrs_status file, but only seconds later it again 
> shows as "DRRS active: yes", and his problem returns/remains.
> 
> It's making the system largely unusable with Linux -- or are we/am I 
> missing something as to configuration?
> 
> The user is as said a new Linux user and will need to stick with generic 
> distribution kernels, Ubuntu here, but the debugfs thing seems to then 
> not work and a kernel parameter appears to not exist. When searching I 
> found this issue also at for example
> 
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1928138
> 
> and on the list at
> 
> https://lists.freedesktop.org/archives/intel-gfx/2017-October/145050.html
> 
> Is there something we/he could do to get DRRS disabled with a generic 
> distribution kernel? Should the i915_drrs_ctl thing have worked?
> 
> And if not, is there a possibility for a kernel parameter that does 
> something akin to that above working test patch (but then right)?
> 
> Kind regards,
> Rene Herman