drm/xe/device: Use poll_timeout_us() to wait for lmem

Now that there's a generic poll_timeout_us(), use it to wait for
LMEM_INIT in GU_CNTL.

Reviewed-by: Maarten Lankhorst <dev@lankhorst.se>
Link: https://lore.kernel.org/r/20250922-xe-iopoll-v4-1-06438311a63f@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

1 files changed, 34 insertions, 31 deletions

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index fdb7b7498920..09f8a66c9728 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -8,6 +8,7 @@
 #include <linux/aperture.h>
 #include <linux/delay.h>
 #include <linux/fault-inject.h>
+#include <linux/iopoll.h>
 #include <linux/units.h>
 
 #include <drm/drm_atomic_helper.h>
@@ -630,16 +631,22 @@ mask_err:
 	return err;
 }
 
-static bool verify_lmem_ready(struct xe_device *xe)
+static int lmem_initializing(struct xe_device *xe)
 {
-	u32 val = xe_mmio_read32(xe_root_tile_mmio(xe), GU_CNTL) & LMEM_INIT;
+	if (xe_mmio_read32(xe_root_tile_mmio(xe), GU_CNTL) & LMEM_INIT)
+		return 0;
+
+	if (signal_pending(current))
+		return -EINTR;
 
-	return !!val;
+	return 1;
 }
 
 static int wait_for_lmem_ready(struct xe_device *xe)
 {
-	unsigned long timeout, start;
+	const unsigned long TIMEOUT_SEC = 60;
+	unsigned long prev_jiffies;
+	int initializing;
 
 	if (!IS_DGFX(xe))
 		return 0;
@@ -647,39 +654,35 @@ static int wait_for_lmem_ready(struct xe_device *xe)
 	if (IS_SRIOV_VF(xe))
 		return 0;
 
-	if (verify_lmem_ready(xe))
+	if (!lmem_initializing(xe))
 		return 0;
 
 	drm_dbg(&xe->drm, "Waiting for lmem initialization\n");
+	prev_jiffies = jiffies;
 
-	start = jiffies;
-	timeout = start + secs_to_jiffies(60); /* 60 sec! */
-
-	do {
-		if (signal_pending(current))
-			return -EINTR;
-
-		/*
-		 * The boot firmware initializes local memory and
-		 * assesses its health. If memory training fails,
-		 * the punit will have been instructed to keep the GT powered
-		 * down.we won't be able to communicate with it
-		 *
-		 * If the status check is done before punit updates the register,
-		 * it can lead to the system being unusable.
-		 * use a timeout and defer the probe to prevent this.
-		 */
-		if (time_after(jiffies, timeout)) {
-			drm_dbg(&xe->drm, "lmem not initialized by firmware\n");
-			return -EPROBE_DEFER;
-		}
-
-		msleep(20);
-
-	} while (!verify_lmem_ready(xe));
+	/*
+	 * The boot firmware initializes local memory and
+	 * assesses its health. If memory training fails,
+	 * the punit will have been instructed to keep the GT powered
+	 * down.we won't be able to communicate with it
+	 *
+	 * If the status check is done before punit updates the register,
+	 * it can lead to the system being unusable.
+	 * use a timeout and defer the probe to prevent this.
+	 */
+	poll_timeout_us(initializing = lmem_initializing(xe),
+			initializing <= 0,
+			20 * USEC_PER_MSEC, TIMEOUT_SEC * USEC_PER_SEC, true);
+	if (initializing < 0)
+		return initializing;
+
+	if (initializing) {
+		drm_dbg(&xe->drm, "lmem not initialized by firmware\n");
+		return -EPROBE_DEFER;
+	}
 
 	drm_dbg(&xe->drm, "lmem ready after %ums",
-		jiffies_to_msecs(jiffies - start));
+		jiffies_to_msecs(jiffies - prev_jiffies));
 
 	return 0;
 }