[Intel-gfx] [PATCH v2 08/14] drm/i915: Sprinkle a few missing locks around shared DDI clock registers

From: Ville Syrjala <ville.syrjala@linux.intel.com>
To: intel-gfx@lists.freedesktop.org
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Subject: [Intel-gfx] [PATCH v2 08/14] drm/i915: Sprinkle a few missing locks around shared DDI clock registers
Date: Thu,  4 Feb 2021 20:10:42 +0200	[thread overview]
Message-ID: <20210204181048.24202-9-ville.syrjala@linux.intel.com> (raw)
In-Reply-To: <20210204181048.24202-1-ville.syrjala@linux.intel.com>

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

The current code attempts to protect the RMWs into global
clock routing registers with a mutex, but forgets to do so
in a few places. Let's remedy that.

Note that at the moment we serialize all modesets onto single
wq, so this shouldn't actually matter. But maybe one day we
wish to attempt parallel modesets again...

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 76aa7d2dba52..0b2a1e0c1b8b 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -3457,8 +3457,12 @@ static void cnl_ddi_disable_clock(struct intel_encoder *encoder)
 	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
 	enum port port = encoder->port;
 
+	mutex_lock(&i915->dpll.lock);
+
 	intel_de_rmw(i915, DPCLKA_CFGCR0,
 		     0, DPCLKA_CFGCR0_DDI_CLK_OFF(port));
+
+	mutex_unlock(&i915->dpll.lock);
 }
 
 static void skl_ddi_enable_clock(struct intel_encoder *encoder,
@@ -3487,8 +3491,12 @@ static void skl_ddi_disable_clock(struct intel_encoder *encoder)
 	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
 	enum port port = encoder->port;
 
+	mutex_lock(&i915->dpll.lock);
+
 	intel_de_rmw(i915, DPLL_CTRL2,
 		     0, DPLL_CTRL2_DDI_CLK_OFF(port));
+
+	mutex_unlock(&i915->dpll.lock);
 }
 
 static void hsw_ddi_enable_clock(struct intel_encoder *encoder,
-- 
2.26.2

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