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charset=UTF-8 Content-Transfer-Encoding: 8bit X-MBO-RS-META: g68zfnwjayxji9kxshey3fmwfqszuo7m X-MBO-RS-ID: e699964b73b7c292c05 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260930_085042_866757_F94D0021 X-CRM114-Status: GOOD ( 26.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 9/29/26 20:55, Vidith Madhu wrote: > On Sat, 26 Sep 2026, Nicolas Frattaroli wrote: >> On Friday, 25 September 2026 05:48:54 Central European Summer Time Vidith Madhu wrote: >> >>> Maybe it would make sense to extend the qms_enabled connector property >>> introduced in this patchset to an enum of {Off, Gaming, QMS}? This would allow >>> a standard path to control the VRR state on the sink, separately from >>> vrr_enabled. >> >> An earlier version of the patch series I was working on internally had a >> VRR limiter property that would either be Off (i.e. Game), Game-Limited, >> QMS-Limited, and it self-inflicted some amount of confusion because of >> the way things were named, so I refactored it to the limiter values being >> what determines whether a limiter is used, and the QMS enable to determine >> whether QMS is used to apply said limit. So my initial reaction is to be >> hesitant about expanding the collection of possible states exposed through >> the uAPI. >> >> To help my understanding: what does >> >> vrr_enabled=true >> $new_property=Off >> >> mean for presentation? > In this case, it should be acceptable to disable VRR on both the source > and sink and effectively ignore vrr_enabled=true. From reading > https://elixir.bootlin.com/linux/v7.2.8/source/drivers/gpu/drm/drm_connector.c#L2370 > vrr_enabled is essentially a hint and there is no need to reject commits > because of its value (at least, that is how we handle it in the NVIDIA > driver). I presume you're referring to this: * The driver will take this property as a hint to enable variable * refresh rate support if the receiver supports it, ie. if the * "vrr_capable" property is true on the &drm_connector object. My reading of that is simply: "If vrr_capable=0, VRR_ENABLED=1 has no effect" (i.e. kind of stating the obvious :). Not sure I see the justification for VRR_ENABLED being "just a hint" beyond that. >> Another state I'm curious about is >> >> vrr_enabled=false >> $new_property=Game >> >> which I assume is the case you're interested in, where the compositor does >> not want VRR presentation but we're keeping the sink in Game mode to avoid >> having the display go blank. > That's right, in this case VRR is enabled on the sink but deactivated > source-side. For NVIDIA, there is a distinct HW "deactivated" state of > VRR, but we could achieve the same result by setting the frame range > limits to a fixed value as you suggested. >> >> is that correct, and something that does need an expanded property? I feel >> like userspace could be smart enough to do that by keeping vrr_enabled=true >> and then setting a fixed target, if the goal is to have non-VRR but with the >> display still in VRR mode. > I agree, I am a little concerned though about the transition period for > compositors to adopt this new model. I know for example KDE is using the > vrr_enabled property for their "AdaptiveSync" option, and it seems like it > would be a regression if all of a sudden toggling it caused display > blanking on newer kernels. Yes it would be, also for mutter, which currently sets VRR_ENABLED to 1 only while there's a surface fully covering the screen. -- Earthling Michel Dänzer \ GNOME / Xwayland / Mesa developer https://redhat.com \ Libre software enthusiast