[PATCH 2/2] drm/i915: Adjust sideband locking a bit for CHV/VLV

ville.syrjala
2015-05-26T17:42:44Z

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

chv_enable_pll() doesn't need to hold sb_lock for the entire duration of
the function. Drop the lock as soon as possible.

valleyview_set_cdclk() does a potential lock+unlock+lock+unlock cycle
with sb_lock. Move Grab the lock a few lines earlier so we can make do
with a single lock+unlock cycle always.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 72b6529..067b1de 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1668,6 +1668,8 @@ static void chv_enable_pll(struct intel_crtc *crtc,
tmp |= DPIO_DCLKP_EN;
vlv_dpio_write(dev_priv, pipe, CHV_CMN_DW14(port), tmp);

+ mutex_unlock(&dev_priv->sb_lock);
+
/*
* Need to wait > 100ns between dclkp clock enable bit and PLL enable.
*/
@@ -1683,8 +1685,6 @@ static void chv_enable_pll(struct intel_crtc *crtc,
/* not sure when this should be written */
I915_WRITE(DPLL_MD(pipe), pipe_config->dpll_hw_state.dpll_md);
POSTING_READ(DPLL_MD(pipe));
-
- mutex_unlock(&dev_priv->sb_lock);
}

static int intel_num_dvo_pipes(struct drm_device *dev)
@@ -5780,12 +5780,13 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
}
mutex_unlock(&dev_priv->rps.hw_lock);

+ mutex_lock(&dev_priv->sb_lock);
+
if (cdclk == 400000) {
u32 divider;

divider = DIV_ROUND_CLOSEST(dev_priv->hpll_freq << 1, cdclk) - 1;

- mutex_lock(&dev_priv->sb_lock);
/* adjust cdclk divider */
val = vlv_cck_read(dev_priv, CCK_DISPLAY_CLOCK_CONTROL);
val &= ~DISPLAY_FREQUENCY_VALUES;
@@ -5796,10 +5797,8 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
DISPLAY_FREQUENCY_STATUS) == (divider << DISPLAY_FREQUENCY_STATUS_SHIFT),
50))
DRM_ERROR("timed out waiting for CDclk change\n");
- mutex_unlock(&dev_priv->sb_lock);
}

- mutex_lock(&dev_priv->sb_lock);
/* adjust self-refresh exit latency value */
val = vlv_bunit_read(dev_priv, BUNIT_REG_BISOC);
val &= ~0x7f;
@@ -5813,6 +5812,7 @@ static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
else
val |= 3000 / 250; /* 3.0 usec */
vlv_bunit_write(dev_priv, BUNIT_REG_BISOC, val);
+
mutex_unlock(&dev_priv->sb_lock);

vlv_update_cdclk(dev);
--
2.3.6