lib/igt_pm: Add lib func to get lpsp capability

This lib function evaluate the lpsp capability from
the connector specific debugfs attribute i915_lpsp_info.

v2:
- changed the lib function prefix igt_output_is_lpsp_capable
  to i915_output_is_lpsp_capable. [Martin]
v3:
- early return for the connector which doesn't support
  lpsp on any platform.
v4:
- debugfs entry changed from i915_lpsp_info to i915_lpsp_capability.
v5:
- return lpsp capability false if i915_lpsp_capability debugfs is not
  present. [Animesh]

Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>

2 files changed, 30 insertions, 0 deletions

diff --git a/lib/igt_pm.c b/lib/igt_pm.c
index 9d441e1b7..b409ec463 100644
--- a/lib/igt_pm.c
+++ b/lib/igt_pm.c
@@ -37,6 +37,7 @@
 #include <dirent.h>
 
 #include "drmtest.h"
+#include "igt_kms.h"
 #include "igt_pm.h"
 #include "igt_aux.h"
 #include "igt_sysfs.h"
@@ -827,3 +828,31 @@ bool igt_pm_pc8_plus_residencies_enabled(int msr_fd)
 
 	return true;
 }
+
+/**
+ * i915_output_is_lpsp_capable:
+ * @drm_fd: fd to drm device
+ * @output: igt output for which lpsp capability need to be evaluated
+ * Check lpsp capability for a given output.
+ *
+ * Returns:
+ * True if given output is lpsp capable otherwise false.
+ */
+bool i915_output_is_lpsp_capable(int drm_fd, igt_output_t *output)
+{
+	char buf[256];
+	int fd, len;
+
+	fd = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_require(fd >= 0);
+	len = igt_debugfs_simple_read(fd, "i915_lpsp_capability",
+				      buf, sizeof(buf));
+
+	/* if i915_lpsp_capability not present return the capability as false */
+	if (len < 0)
+		return false;
+
+	close(fd);
+
+	return strstr(buf, "LPSP: capable");
+}
diff --git a/lib/igt_pm.h b/lib/igt_pm.h
index 5e4384522..162d3ca3c 100644
--- a/lib/igt_pm.h
+++ b/lib/igt_pm.h
@@ -53,5 +53,6 @@ enum igt_runtime_pm_status igt_get_runtime_pm_status(void);
 bool igt_wait_for_pm_status(enum igt_runtime_pm_status status);
 bool igt_pm_dmc_loaded(int debugfs);
 bool igt_pm_pc8_plus_residencies_enabled(int msr_fd);
+bool i915_output_is_lpsp_capable(int drm_fd, igt_output_t *output);
 
 #endif /* IGT_PM_H */