1 files changed, 28 insertions, 22 deletions

diff --git a/drivers/gpu/drm/xe/xe_devcoredump.c b/drivers/gpu/drm/xe/xe_devcoredump.c
index 7a8af2311318..203e3038cc81 100644
--- a/drivers/gpu/drm/xe/xe_devcoredump.c
+++ b/drivers/gpu/drm/xe/xe_devcoredump.c
@@ -171,14 +171,32 @@ static void xe_devcoredump_snapshot_free(struct xe_devcoredump_snapshot *ss)
 
 #define XE_DEVCOREDUMP_CHUNK_MAX	(SZ_512M + SZ_1G)
 
+/**
+ * xe_devcoredump_read() - Read data from the Xe device coredump snapshot
+ * @buffer: Destination buffer to copy the coredump data into
+ * @offset: Offset in the coredump data to start reading from
+ * @count: Number of bytes to read
+ * @data: Pointer to the xe_devcoredump structure
+ * @datalen: Length of the data (unused)
+ *
+ * Reads a chunk of the coredump snapshot data into the provided buffer.
+ * If the devcoredump is smaller than 1.5 GB (XE_DEVCOREDUMP_CHUNK_MAX),
+ * it is read directly from a pre-written buffer. For larger devcoredumps,
+ * the pre-written buffer must be periodically repopulated from the snapshot
+ * state due to kmalloc size limitations.
+ *
+ * Return: Number of bytes copied on success, or a negative error code on failure.
+ */
 static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
 				   size_t count, void *data, size_t datalen)
 {
 	struct xe_devcoredump *coredump = data;
 	struct xe_devcoredump_snapshot *ss;
-	ssize_t byte_copied;
+	ssize_t byte_copied = 0;
 	u32 chunk_offset;
 	ssize_t new_chunk_position;
+	bool pm_needed = false;
+	int ret = 0;
 
 	if (!coredump)
 		return -ENODEV;
@@ -188,20 +206,19 @@ static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
 	/* Ensure delayed work is captured before continuing */
 	flush_work(&ss->work);
 
-	if (ss->read.size > XE_DEVCOREDUMP_CHUNK_MAX)
+	pm_needed = ss->read.size > XE_DEVCOREDUMP_CHUNK_MAX;
+	if (pm_needed)
 		xe_pm_runtime_get(gt_to_xe(ss->gt));
 
 	mutex_lock(&coredump->lock);
 
 	if (!ss->read.buffer) {
-		mutex_unlock(&coredump->lock);
-		return -ENODEV;
+		ret = -ENODEV;
+		goto unlock;
 	}
 
-	if (offset >= ss->read.size) {
-		mutex_unlock(&coredump->lock);
-		return 0;
-	}
+	if (offset >= ss->read.size)
+		goto unlock;
 
 	new_chunk_position = div_u64_rem(offset,
 					 XE_DEVCOREDUMP_CHUNK_MAX,
@@ -221,12 +238,13 @@ static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
 		ss->read.size - offset;
 	memcpy(buffer, ss->read.buffer + chunk_offset, byte_copied);
 
+unlock:
 	mutex_unlock(&coredump->lock);
 
-	if (ss->read.size > XE_DEVCOREDUMP_CHUNK_MAX)
+	if (pm_needed)
 		xe_pm_runtime_put(gt_to_xe(ss->gt));
 
-	return byte_copied;
+	return byte_copied ? byte_copied : ret;
 }
 
 static void xe_devcoredump_free(void *data)
@@ -313,13 +331,9 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
 {
 	struct xe_devcoredump_snapshot *ss = &coredump->snapshot;
 	struct xe_guc *guc = exec_queue_to_guc(q);
-	u32 adj_logical_mask = q->logical_mask;
-	u32 width_mask = (0x1 << q->width) - 1;
 	const char *process_name = "no process";
-
 	unsigned int fw_ref;
 	bool cookie;
-	int i;
 
 	ss->snapshot_time = ktime_get_real();
 	ss->boot_time = ktime_get_boottime();
@@ -335,14 +349,6 @@ static void devcoredump_snapshot(struct xe_devcoredump *coredump,
 	INIT_WORK(&ss->work, xe_devcoredump_deferred_snap_work);
 
 	cookie = dma_fence_begin_signalling();
-	for (i = 0; q->width > 1 && i < XE_HW_ENGINE_MAX_INSTANCE;) {
-		if (adj_logical_mask & BIT(i)) {
-			adj_logical_mask |= width_mask << i;
-			i += q->width;
-		} else {
-			++i;
-		}
-	}
 
 	/* keep going if fw fails as we still want to save the memory and SW data */
 	fw_ref = xe_force_wake_get(gt_to_fw(q->gt), XE_FORCEWAKE_ALL);