Comment 5 for bug 1925685

Hi Kai-Heng:

Thank you for the response. Could we see this applied to 20.04 LTS (kernel 5.8)
as we do not ship non-LTS releases.

To help ensure the safety of this patch, we did extensive testing throughout the
weekend on 8 systems and 10 configurations.

We found the following:

1. The ‘Patched’ kernel FIXED ALL ISSUES for all flickering panels
2. The 'Patched' kernel systems CONTINUED TO WORK WELL an additional 5 systems
   tested, all with different panels
3. The 'Unpatched' kernel almost always caused severe flickering for susceptible
   systems after a single sleep-wake cycle or after warm
4. We saw similar flickering regardless of which GFX driver was used. Flickering
   was eliminated on all when the patch was applied.

The patch we provided and tested (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1925685/+attachment/5491421/+files/drm-intel-both.patch
) combines the original patch with your proposed changes. We did this because
applying both patches sequentially resulted in a minor conflict. We encourage
you to try it to see for yourself. Your suggestion worked better than the original
proposal, as it fixed ALL issues on affected systems.

+---------------------------------------------------------------------------+
| Intel GFX Patch Test Results |
+-----------+----------+---------+-----------------+------------+-----------+
| CPU | GPUs | Driver | Panel | Unpatched | Patched |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-10870H | i630 | Nouveau | LG Display | Bad Glitch | No Issues |
| 3 Samples | RTX 3060 | (USB) | LP156WFG-SPB3 | + Flicker | |
| | 3070 | | LGD Model 1573 | | |
| | 3080 | | | | |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-10870H | i630 | Intel | LG Display | Bad Glitch | No Issues |
| | RTX 3060 | (NVMe) | LP156WFG-SPB3 | + Flicker | |
| | | | LGD Model 1573 | | |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-10870H | i630 | Nvidia | LG Display | Bad Glitch | No Issues |
| | RTX 3060 | (NVMe) | LP156WFG-SPB3 | + Flicker | |
| | | | LGD Model 1573 | | |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-10875H | i630 | Nouveau | LM156LF-1F02 | No Issues | No Issues |
| | RTX 2060 | (USB) | NCP Model 75 | | |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-9750H | i630 | Nouveau | CMN N161HCA-GA1 | -- | No Issues |
| | RTX 2070 | (USB) | | | |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-8750H | i630 | Nouveau | LGD Model 1472 | No Issues | No Issues |
| | GTX 1060 | (USB) | | | |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-6700HQ | i530 | Nvidia | LGD Model 1135 | -- | No Issues |
| | 970M | (NVMe) | | | |
+-----------+----------+---------+-----------------+------------+-----------+
| i7-3720QM | HD 4000 | Intel | LEN Model 16562 | -- | No Issues |
| | | (USB) | | | |
+-----------+----------+---------+-----------------+------------+-----------+

Testing Notes

1. We ran all tests with 5 sleep-wake cycles with the Chrome browser running
   a 1080p video in one tab and a WebGL Aquarium in the other.

2. The 'Unpatched' kernel is 5.8.0-42-generic from the Ubuntu 20.04 LTS
   repository.

3. The ‘Patched’ kernel is 5.8.0-50-generic from the Ubuntu 20.04 LTS
   repository source with the above patch applied. We compiled packages and
   installed them in the test image.

4. We tested most systems using a live-session USB image. However, we tested
   some systems using an NVMe image so we could compare Intel and Nvidia drivers
   as well.

5. The OS used for all testing was Ubuntu 20.04.2 with the KDE desktop
   (Kubuntu 20.04.2).

6. We skipped testing 'Unpatched' kernels on older systems as what matters is
   that the 'Patched' kernel continues to work, which it does.

Sincerely, Mike