[Pdbg] [PATCH 5/7] libpdbg: Rescan fsi bus only once

[Amitay Isaacs]

On rescan, kernel driver re-creates all the slave devices.  This
invalidates all the slave deviced opened before the scan.

Signed-off-by: Amitay Isaacs <amitay at ozlabs.org>
---
 libpdbg/kernel.c | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/libpdbg/kernel.c b/libpdbg/kernel.c
index 2cc81f2..912895a 100644
--- a/libpdbg/kernel.c
+++ b/libpdbg/kernel.c
@@ -116,6 +116,15 @@ static void kernel_fsi_scan_devices(void)
 	const char *kernel_path = kernel_get_fsi_path();
 	char *path;
 	int rc, fd;
+	static bool scanned = false;
+
+	/*
+	 * On fsi bus rescan, kernel re-creates all the slave device entries.
+	 * It means any currently open devices will be invalid and need to be
+	 * re-opened.  So avoid scanning multiple times.
+	 */
+	if (scanned)
+		return;
 
 	if (!kernel_path)
 		return;
@@ -139,12 +148,13 @@ static void kernel_fsi_scan_devices(void)
 
 	free(path);
 	close(fd);
+
+	scanned = true;
 }
 
 int kernel_fsi_probe(struct pdbg_target *target)
 {
 	struct fsi *fsi = target_to_fsi(target);
-	int tries = 5;
 	int rc;
 	const char *kernel_path = kernel_get_fsi_path();
 	const char *fsi_path;
@@ -162,24 +172,19 @@ int kernel_fsi_probe(struct pdbg_target *target)
 		return rc;
 	}
 
-	while (tries) {
-		/* Open first raw device */
-		fsi->fd = open(path, O_RDWR | O_SYNC);
-		if (fsi->fd >= 0) {
-			free(path);
-			return 0;
-		}
-		tries--;
-
-		/* Scan */
-		kernel_fsi_scan_devices();
-		sleep(1);
-	}
-	if (fsi->fd < 0) {
-		PR_ERROR("Unable to open %s\n", path);
+	/* Always scan the fsi bus once */
+	kernel_fsi_scan_devices();
+	sleep(1);
+
+	/* Open first raw device */
+	fsi->fd = open(path, O_RDWR | O_SYNC);
+	if (fsi->fd >= 0) {
 		free(path);
+		return 0;
 	}
 
+	PR_ERROR("Unable to open %s\n", path);
+	free(path);
 	return -1;
 }
 
-- 
2.26.2