[PATCH 1/2] drm/i915: Disable Panel Self Refresh (PSR) by default

[Sultan Alsawaf <sultan@kerneltoast.com>]

From: Sultan Alsawaf <sultan@kerneltoast.com>

On all Dell laptops with panels and chipsets that support PSR (an
esoteric power-saving mechanism), both PSR1 and PSR2 cause flickering
and graphical glitches, sometimes to the point of making the laptop
unusable. Many laptops don't support PSR so it isn't known if PSR works
correctly on any consumer hardware as of 5.4. PSR was enabled by default
in 5.0 for capable hardware, so this patch just restores the previous
functionality of PSR being disabled by default.

More info is available on the freedesktop bug:
https://gitlab.freedesktop.org/drm/intel/issues/425

Cc: <stable@vger.kernel.org> # 5.4.x
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
---
 drivers/gpu/drm/i915/i915_params.c | 3 +--
 drivers/gpu/drm/i915/i915_params.h | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 296452f9efe4..4a0d37f7cf49 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -84,8 +84,7 @@ i915_param_named_unsafe(enable_hangcheck, bool, 0600,
 
 i915_param_named_unsafe(enable_psr, int, 0600,
 	"Enable PSR "
-	"(0=disabled, 1=enabled) "
-	"Default: -1 (use per-chip default)");
+	"(-1=use per-chip default, 0=disabled [default], 1=enabled) ");
 
 i915_param_named_unsafe(force_probe, charp, 0400,
 	"Force probe the driver for specified devices. "
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index d29ade3b7de6..715888811593 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -50,7 +50,7 @@ struct drm_printer;
 	param(int, vbt_sdvo_panel_type, -1) \
 	param(int, enable_dc, -1) \
 	param(int, enable_fbc, -1) \
-	param(int, enable_psr, -1) \
+	param(int, enable_psr, 0) \
 	param(int, disable_power_well, -1) \
 	param(int, enable_ips, 1) \
 	param(int, invert_brightness, 0) \
-- 
2.26.0