[Regression] Panel flickering on Dell XPS 13 9360 with drm-fixes-2025-06-28 merged (Linux 6.16-rc4)

[Imre Deak]

On Sun, Jun 29, 2025 at 11:04:31PM +0200, Paul Menzel wrote:
> Dear Linux folks,
> 
> 
> Just a heads-up, that very likely, merging of branch *drm-fixes-2025-06-28*
> causes flickering of the panel of the Intel Kaby Lake laptop Dell XPS 13
> 9360. 6.16.0-rc3 works fine, and with 6.16-rc3-00329-gdfba48a70cb6 the panel
> flickers. I try to bisect, but maybe you already have an idea.

One possibility is:
a3ef3c2da675 ("drm/dp: Change AUX DPCD probe address from DPCD_REV to LANE0_1_STATUS")

Could you open a ticket for this and provide a drm.debug=0x10e log with
6.16-rc4 and try if the following commits in drm-tip fixes the issue?:

5281cbe0b55a ("drm/edid: Define the quirks in an enum list")
0b4aa85e8981 ("drm/edid: Add support for quirks visible to DRM core and drivers")
b87ed522b364 ("drm/dp: Add an EDID quirk for the DPCD register access probe")
ed3648b9ec4c ("drm/i915/dp: Disable the AUX DPCD probe quirk if it's not required")

I also pushed these to:
https://github.com/ideak/linux/commits/dpcd-probe-quirk

Thanks,
Imre

> Kind regards,
> 
> Paul
> 
> 
> $ lspci -nn
> 00:00.0 Host bridge [0600]: Intel Corporation Xeon E3-1200 v6/7th Gen Core
> Processor Host Bridge/DRAM Registers [8086:5904] (rev 02)
> 00:02.0 VGA compatible controller [0300]: Intel Corporation HD Graphics 620
> [8086:5916] (rev 02)
> 00:04.0 Signal processing controller [1180]: Intel Corporation Xeon E3-1200
> v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem [8086:1903] (rev 02)
> 00:14.0 USB controller [0c03]: Intel Corporation Sunrise Point-LP USB 3.0
> xHCI Controller [8086:9d2f] (rev 21)
> 00:14.2 Signal processing controller [1180]: Intel Corporation Sunrise
> Point-LP Thermal subsystem [8086:9d31] (rev 21)
> 00:15.0 Signal processing controller [1180]: Intel Corporation Sunrise
> Point-LP Serial IO I2C Controller #0 [8086:9d60] (rev 21)
> 00:15.1 Signal processing controller [1180]: Intel Corporation Sunrise
> Point-LP Serial IO I2C Controller #1 [8086:9d61] (rev 21)
> 00:16.0 Communication controller [0780]: Intel Corporation Sunrise Point-LP
> CSME HECI #1 [8086:9d3a] (rev 21)
> 00:1c.0 PCI bridge [0604]: Intel Corporation Sunrise Point-LP PCI Express
> Root Port #1 [8086:9d10] (rev f1)
> 00:1c.4 PCI bridge [0604]: Intel Corporation Sunrise Point-LP PCI Express
> Root Port #5 [8086:9d14] (rev f1)
> 00:1c.5 PCI bridge [0604]: Intel Corporation Sunrise Point-LP PCI Express
> Root Port #6 [8086:9d15] (rev f1)
> 00:1d.0 PCI bridge [0604]: Intel Corporation Sunrise Point-LP PCI Express
> Root Port #9 [8086:9d18] (rev f1)
> 00:1f.0 ISA bridge [0601]: Intel Corporation Sunrise Point-LP LPC Controller
> [8086:9d58] (rev 21)
> 00:1f.2 Memory controller [0580]: Intel Corporation Sunrise Point-LP PMC
> [8086:9d21] (rev 21)
> 00:1f.3 Audio device [0403]: Intel Corporation Sunrise Point-LP HD Audio
> [8086:9d71] (rev 21)
> 00:1f.4 SMBus [0c05]: Intel Corporation Sunrise Point-LP SMBus [8086:9d23]
> (rev 21)
> 3a:00.0 Network controller [0280]: Qualcomm Atheros QCA6174 802.11ac
> Wireless Network Adapter [168c:003e] (rev 32)
> 3b:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI
> Express Card Reader [10ec:525a] (rev 01)
> 3c:00.0 Non-Volatile memory controller [0108]: SK hynix PC300 NVMe Solid
> State Drive 512GB [1c5c:1284]