lib/psr: Add support for toggling edp psr through debugfs, v5.

It's harmful to write to enable_psr at runtime, and the patch that allows
us to change i915_edp_psr_debug with the panel running will require us
to abandon the module parameter. Hence the userspace change needs to be
put in IGT first before we can change it at kernel time.

Toggling it to debugfs will mean we can skip a modeset when changing our
feature set.

Changes since v1:
- Rebase with the previous patches dropped.
Changes since v2:
- Rebase on top of new api in i915_edp_psr_debug.
Changes since v3:
- Enable IRQ debugging for extra logging.
- Force PSR1 mode. (dhnkrn)
- Move PSR enable/disable functions to lib/igt_psr. (dhnkrn)
Changes since v4:
- Redisable irqs right away when debugfs api doesn't work. (dhnkrn)
- Use hex everywhere. (dhnkrn)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
[mlankhorst: Fix -ENODEV explanation in has_psr_debugfs (dhnkrn)]
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>

1 files changed, 85 insertions, 1 deletions

diff --git a/lib/igt_psr.c b/lib/igt_psr.c
index c979b0b5..bc142632 100644
--- a/lib/igt_psr.c
+++ b/lib/igt_psr.c
@@ -21,7 +21,9 @@
  * IN THE SOFTWARE.
  */
 
-#include  "igt_psr.h"
+#include "igt_psr.h"
+#include "igt_sysfs.h"
+#include <errno.h>
 
 bool psr_active(int fd, bool check_active)
 {
@@ -38,3 +40,85 @@ bool psr_wait_entry(int fd)
 {
 	return igt_wait(psr_active(fd, true), 500, 1);
 }
+
+static ssize_t psr_write(int fd, const char *buf)
+{
+	return igt_sysfs_write(fd, "i915_edp_psr_debug", buf, strlen(buf));
+}
+
+static int has_psr_debugfs(int fd)
+{
+	int ret;
+
+	/*
+	 * Check if new PSR debugfs api is usable by writing an invalid value.
+	 * Legacy mode will return OK here, debugfs api will return -EINVAL.
+	 * -ENODEV is returned when PSR is unavailable.
+	 */
+	ret = psr_write(fd, "0xf");
+	if (ret == -EINVAL)
+		return 0;
+	else if (ret < 0)
+		return ret;
+
+	/* legacy debugfs api, we enabled irqs by writing, disable them. */
+	psr_write(fd, "0");
+	return -EINVAL;
+}
+
+static bool psr_modparam_set(int val)
+{
+	static int oldval = -1;
+
+	igt_set_module_param_int("enable_psr", val);
+
+	if (val == oldval)
+		return false;
+
+	oldval = val;
+	return true;
+}
+
+static int psr_restore_debugfs_fd = -1;
+
+static void restore_psr_debugfs(int sig)
+{
+	psr_write(psr_restore_debugfs_fd, "0");
+}
+
+static bool psr_set(int fd, bool enable)
+{
+	int ret;
+
+	ret = has_psr_debugfs(fd);
+	if (ret == -ENODEV) {
+		igt_skip_on_f(enable, "PSR not available\n");
+		return false;
+	}
+
+	if (ret == -EINVAL) {
+		ret = psr_modparam_set(enable);
+	} else {
+		ret = psr_write(fd, enable ? "0x3" : "0x1");
+		igt_assert(ret > 0);
+	}
+
+	/* Restore original value on exit */
+	if (psr_restore_debugfs_fd == -1) {
+		psr_restore_debugfs_fd = dup(fd);
+		igt_assert(psr_restore_debugfs_fd >= 0);
+		igt_install_exit_handler(restore_psr_debugfs);
+	}
+
+	return ret;
+}
+
+bool psr_enable(int fd)
+{
+	return psr_set(fd, true);
+}
+
+bool psr_disable(int fd)
+{
+	return psr_set(fd, false);
+}