soc: apple: rtkit: Use high prio work queue

[ Upstream commit 22af2fa ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 78b6b2fe17a2e91b70c0a1347b4722da98f4cac3)

Author: jannau

drivers/soc/apple/rtkit.c

@@ -744,7 +744,7 @@ struct apple_rtkit *apple_rtkit_init(struct device *dev, void *cookie,
 	rtk->mbox_cl.rx_callback = &apple_rtkit_rx;
 	rtk->mbox_cl.tx_done = &apple_rtkit_tx_done;
 
-	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;