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

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Message-Id: <20200330163006.4064-2-sultan@kerneltoast.com>
Date:   Mon, 30 Mar 2020 09:30:06 -0700
From:   Sultan Alsawaf <sultan@...neltoast.com>
To:     linux-kernel@...r.kernel.org
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        Sultan Alsawaf <sultan@...neltoast.com>, stable@...r.kernel.org
Subject: [PATCH 1/1] drm/i915: Disable Panel Self Refresh (PSR) by default

From: Sultan Alsawaf <sultan@...neltoast.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@...r.kernel.org> # 5.4.x, 5.5.x
Signed-off-by: Sultan Alsawaf <sultan@...neltoast.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