[Intel-gfx] [RFC 3/3] drm/i915: Creating guc log file in drmfs instead of debugfs

[swati.dhingra at intel.com]

From: Swati Dhingra <swati.dhingra at intel.com>

In the current scenario, the relay API fit well only with debugfs, due to
availability of parent dentry. Any other existing filesystem was not feasible for
holding guc logs, due to incompatibility with relay. But this makes the  guc_log
file unavailable on the production kernels.

GuC log file can therefore be one of candidates for movement to the drmfs
filesystem, which can satisfy all the requirements needed by relay API, and can
house any relayfs based output file.

The patch moves the parent directory of guc 'log_dir' from debugfs_root to
drmfs_root, while using the drmfs api's to create the requisite files.

Signed-off-by: Sourab Gupta <sourab.gupta at intel.com>
Signed-off-by: Swati Dhingra <swati.dhingra at intel.com>
---
 drivers/gpu/drm/i915/i915_guc_submission.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 4462112..cd2e8ed 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -24,6 +24,7 @@
 #include <linux/firmware.h>
 #include <linux/circ_buf.h>
 #include <linux/debugfs.h>
+#include <linux/drmfs.h>
 #include <linux/relay.h>
 #include "i915_drv.h"
 #include "intel_guc.h"
@@ -923,7 +924,7 @@ static int subbuf_start_callback(struct rchan_buf *buf,
 }
 
 /*
- * file_create() callback. Creates relay file in debugfs.
+ * file_create() callback. Creates relay file.
  */
 static struct dentry *create_buf_file_callback(const char *filename,
 					       struct dentry *parent,
@@ -949,17 +950,26 @@ static struct dentry *create_buf_file_callback(const char *filename,
 	 * dentry of the file associated with the channel buffer and that file's
 	 * name need not be same as the filename passed as an argument.
 	 */
+#if defined(CONFIG_DRMFS)
+	buf_file = drmfs_create_file("guc_log", mode,
+				       parent, buf, &relay_file_operations);
+#else
 	buf_file = debugfs_create_file("guc_log", mode,
 				       parent, buf, &relay_file_operations);
+#endif
 	return buf_file;
 }
 
 /*
- * file_remove() default callback. Removes relay file in debugfs.
+ * file_remove() default callback. Removes relay file.
  */
 static int remove_buf_file_callback(struct dentry *dentry)
 {
+#if defined(CONFIG_DRMFS)
+	drmfs_remove(dentry);
+#else
 	debugfs_remove(dentry);
+#endif
 	return 0;
 }
 
@@ -1009,6 +1019,10 @@ static int guc_log_create_relay_file(struct intel_guc *guc)
 	struct dentry *log_dir;
 	int ret;
 
+#if defined(CONFIG_DRMFS)
+	/* Create the log file in drmfs dir: /sys/kernel/drm/i915/ */
+	log_dir = dev_priv->drm.driver->drmfs_root;
+#else
 	/* For now create the log file in /sys/kernel/debug/dri/0 dir */
 	log_dir = dev_priv->drm.primary->debugfs_root;
 
@@ -1021,10 +1035,12 @@ static int guc_log_create_relay_file(struct intel_guc *guc)
 	 *      relay channel.
 	 * ii)  Should be able to use 'relay_file_operations' fops for the file.
 	 * iii) Set the 'i_private' field of file's inode to the pointer of
-	 *	relay channel buffer.
+	 *      relay channel buffer.
 	 */
+#endif
+
 	if (!log_dir) {
-		DRM_ERROR("Debugfs dir not available yet for GuC log file\n");
+		DRM_ERROR("Root dir not available yet for GuC log file\n");
 		return -ENODEV;
 	}
 
@@ -1265,7 +1281,7 @@ static int guc_log_create_extras(struct intel_guc *guc)
 	if (!guc->log.relay_chan) {
 		/* Create a relay channel, so that we have buffers for storing
 		 * the GuC firmware logs, the channel will be linked with a file
-		 * later on when debugfs is registered.
+		 * later on when debugfs/drmfs is registered.
 		 */
 		ret = guc_log_create_relay_channel(guc);
 		if (ret)
-- 
2.7.4