soc: apple: rtkit: Use high prio work queue

rtkit messages as communication with the DCP firmware for framebuffer
swaps or input events are time critical so use WQ_HIGHPRI to prevent
user space CPU load to increase latency.
With kwin_wayland 6's explicit sync mode user space load was able to
delay the IOMFB rtkit communication enough to miss vsync for surface
swaps. Minimal test scenario is constantly resizing a glxgears
Xwayland window.

Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Link: https://lore.kernel.org/r/20250226-apple-soc-misc-v2-3-c3ec37f9021b@svenpeter.dev
Signed-off-by: Sven Peter <sven@svenpeter.dev>

diff --git a/drivers/soc/apple/rtkit.c b/drivers/soc/apple/rtkit.c
index 7e7b4f64ab172f4c1b978388f3fffb0cdb7911b2..4b78463dd5a1002d2a8f54726729d2370b8dc560 100644 (file)
--- a/drivers/soc/apple/rtkit.c
+++ b/drivers/soc/apple/rtkit.c
@@ -696,7 +696,7 @@ struct apple_rtkit *apple_rtkit_init(struct device *dev, void *cookie,
        rtk->mbox->rx = apple_rtkit_rx;
        rtk->mbox->cookie = rtk;
 
-       rtk->wq = alloc_ordered_workqueue("rtkit-%s", WQ_MEM_RECLAIM,
+       rtk->wq = alloc_ordered_workqueue("rtkit-%s", WQ_HIGHPRI | WQ_MEM_RECLAIM,
                                          dev_name(rtk->dev));
        if (!rtk->wq) {
                ret = -ENOMEM;