[igt-dev] [PATCH i-g-t] lib/debugfs: Use a blocking read in igt_pipe_crc_get_single()

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

All users of igt_pipe_crc_get_single() want a blocking read even if
the fd was opened in nonblocking mode. Make it so.

Cc: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 lib/igt_debugfs.c           | 35 ++++++++++++-----------------------
 lib/igt_debugfs.h           |  2 +-
 tests/kms_chv_cursor_fail.c |  2 +-
 3 files changed, 14 insertions(+), 25 deletions(-)

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index baedc2255ac9..d151d9b23ed4 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -757,8 +757,13 @@ static void read_one_crc(igt_pipe_crc_t *pipe_crc, igt_crc_t *out)
 {
 	int ret;
 
-	while ((ret = read_crc(pipe_crc, out)) <= 0 && ret != -EINVAL)
-		usleep(1000);
+	fcntl(pipe_crc->crc_fd, F_SETFL, pipe_crc->flags & ~O_NONBLOCK);
+
+	do {
+		ret = read_crc(pipe_crc, out);
+	} while (ret == -EINTR);
+
+	fcntl(pipe_crc->crc_fd, F_SETFL, pipe_crc->flags);
 }
 
 /**
@@ -926,12 +931,8 @@ void igt_pipe_crc_drain(igt_pipe_crc_t *pipe_crc)
  * @pipe_crc: pipe CRC object
  * @crc: buffer pointer for the captured CRC value
  *
- * Read a single @crc from @pipe_crc. This function does not block
- * when nonblocking CRC is requested, and will return false if no CRC
- * can be captured.
- *
- * If opened in blocking mode it will always block until a new CRC is read, like
- * igt_pipe_crc_collect_crc().
+ * Read a single @crc from @pipe_crc. This function blocks even
+ * when nonblocking CRC is requested.
  *
  * Callers must start and stop the capturing themselves by calling
  * igt_pipe_crc_start() and igt_pipe_crc_stop(). For one-shot CRC collecting
@@ -943,22 +944,11 @@ void igt_pipe_crc_drain(igt_pipe_crc_t *pipe_crc)
  * Returns:
  * Whether a crc is captured, only false in non-blocking mode.
  */
-bool
-igt_pipe_crc_get_single(igt_pipe_crc_t *pipe_crc, igt_crc_t *crc)
+void igt_pipe_crc_get_single(igt_pipe_crc_t *pipe_crc, igt_crc_t *crc)
 {
-	bool found = true;
+	read_one_crc(pipe_crc, crc);
 
-	if (pipe_crc->flags & O_NONBLOCK) {
-		int ret = read_crc(pipe_crc, crc);
-
-		found = ret > 0;
-	} else
-		read_one_crc(pipe_crc, crc);
-
-	if (found)
-		crc_sanity_checks(crc);
-
-	return found;
+	crc_sanity_checks(crc);
 }
 
 /**
@@ -976,7 +966,6 @@ igt_pipe_crc_get_current(int drm_fd, igt_pipe_crc_t *pipe_crc, igt_crc_t *crc)
 {
 	unsigned vblank = kmstest_get_vblank(drm_fd, pipe_crc->pipe, 0);
 
-	igt_assert(!(pipe_crc->flags & O_NONBLOCK));
 	do {
 		read_one_crc(pipe_crc, crc);
 
diff --git a/lib/igt_debugfs.h b/lib/igt_debugfs.h
index 9f81be0a24de..58ca07f5c15d 100644
--- a/lib/igt_debugfs.h
+++ b/lib/igt_debugfs.h
@@ -132,7 +132,7 @@ __attribute__((warn_unused_result))
 int igt_pipe_crc_get_crcs(igt_pipe_crc_t *pipe_crc, int n_crcs,
 			  igt_crc_t **out_crcs);
 void igt_pipe_crc_drain(igt_pipe_crc_t *pipe_crc);
-bool igt_pipe_crc_get_single(igt_pipe_crc_t *pipe_crc, igt_crc_t *out_crc);
+void igt_pipe_crc_get_single(igt_pipe_crc_t *pipe_crc, igt_crc_t *out_crc);
 void igt_pipe_crc_get_current(int drm_fd, igt_pipe_crc_t *pipe_crc, igt_crc_t *crc);
 
 void igt_pipe_crc_collect_crc(igt_pipe_crc_t *pipe_crc, igt_crc_t *out_crc);
diff --git a/tests/kms_chv_cursor_fail.c b/tests/kms_chv_cursor_fail.c
index 7138e549aeb7..8e50978d0be1 100644
--- a/tests/kms_chv_cursor_fail.c
+++ b/tests/kms_chv_cursor_fail.c
@@ -258,7 +258,7 @@ static void prepare_crtc(data_t *data)
 
 	/* get reference crc w/o cursor */
 	igt_pipe_crc_start(data->pipe_crc);
-	igt_assert(igt_pipe_crc_get_single(data->pipe_crc, &data->ref_crc));
+	igt_pipe_crc_get_single(data->pipe_crc, &data->ref_crc);
 }
 
 static void test_crtc(data_t *data, unsigned int edges)
-- 
2.16.4