soc: apple: rtkit: Use high prio work queue

[ Upstream commit 22af2fac88fa5dbc310bfe7d0b66d4de3ac47305 ]

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>

diff --git a/drivers/soc/apple/rtkit.c b/drivers/soc/apple/rtkit.c
index e6d940292c9fbdfc4cd42020e89aca2662c5cdce..00d59a81db88bd927944152f31411683edd18f03 100644 (file)
--- a/drivers/soc/apple/rtkit.c
+++ b/drivers/soc/apple/rtkit.c
@@ -667,7 +667,7 @@ 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;