[PATCH 0/1] drm/i915: Disable Panel Self Refresh (PSR) by default

[PATCH 0/1] drm/i915: Disable Panel Self Refresh (PSR) by default

[Sultan Alsawaf]

From: Sultan Alsawaf <sultan@kerneltoast.com>

Hi,

Laptops which support an esoteric power-saving mechanism called Panel Self
Refresh (PSR) suffer from severe graphical corruption and flickering. Enabled by
default in 5.0, PSR causes graphical corruption to the point of unusability on
many Dell laptops made within the past few years, since they typically support
PSR. A bug was filed with Intel several months ago for this with more
information [1]. I suspect most of the community hasn't been affected by this
bug because ThinkPads and many other laptops I checked didn't support PSR. As of
writing, the issues I observed with PSR are neither fully fixed in Intel's
drm-tip branch nor in 5.6. Disabling PSR by default brings us safely back to
pre-5.0 behavior, remedying the glitches. Also, Ubuntu now ships with PSR
disabled by default in its affected kernels, so there is distro support behind
this change.

Thanks,
Sultan

[1] https://gitlab.freedesktop.org/drm/intel/issues/425

Sultan Alsawaf (1):
  drm/i915: Disable Panel Self Refresh (PSR) by default

 drivers/gpu/drm/i915/i915_params.c | 3 +--
 drivers/gpu/drm/i915/i915_params.h | 2 +-
 2 files changed, 2 insertions(+), 3 deletions(-)

-- 
2.26.0

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

[Sultan Alsawaf]

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 right now. 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, 5.5.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 1dd1f3652795..0c4661fcf011 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -85,8 +85,7 @@ 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 31b88f297fbc..4a9a3df7d292 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