drm/i915: rework locking for intel_dpio|sbi_read|write
Spinning for up to 200 us with interrupts locked out is not good. So
let's just spin (and even that seems to be excessive).
And we don't call these functions from interrupt context, so this is
not required. Besides that doing anything in interrupt contexts which
might take a few hundred us is a no-go. So just convert the entire
thing to a mutex. Also move the mutex-grabbing out of the read/write
functions (add a WARN_ON(!is_locked)) instead) since all callers are
nicely grouped together.
Finally the real motivation for this change: Dont grab the modeset
mutex in the dpio debugfs file, we don't need that consistency. And
correctness of the dpio interface is ensured with the dpio_lock.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 7e516ee..7047c4a9f 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1633,7 +1633,7 @@
return 0;
}
- ret = mutex_lock_interruptible(&dev->mode_config.mutex);
+ ret = mutex_lock_interruptible(&dev_priv->dpio_lock);
if (ret)
return ret;
@@ -1662,7 +1662,7 @@
seq_printf(m, "DPIO_FASTCLK_DISABLE: 0x%08x\n",
intel_dpio_read(dev_priv, DPIO_FASTCLK_DISABLE));
- mutex_unlock(&dev->mode_config.mutex);
+ mutex_unlock(&dev_priv->dpio_lock);
return 0;
}
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 0c2ab40..a99c46d 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1599,7 +1599,7 @@
spin_lock_init(&dev_priv->irq_lock);
spin_lock_init(&dev_priv->error_lock);
spin_lock_init(&dev_priv->rps.lock);
- spin_lock_init(&dev_priv->dpio_lock);
+ mutex_init(&dev_priv->dpio_lock);
mutex_init(&dev_priv->rps.hw_lock);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e55303e..514aee8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -686,7 +686,7 @@
struct pm_qos_request pm_qos;
/* DPIO indirect register protection */
- spinlock_t dpio_lock;
+ struct mutex dpio_lock;
/** Cached value of IMR to avoid reads in updating the bitfield */
u32 pipestat[2];
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 115bf62..2a01b09 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -416,13 +416,11 @@
u32 intel_dpio_read(struct drm_i915_private *dev_priv, int reg)
{
- unsigned long flags;
- u32 val = 0;
+ WARN_ON(!mutex_is_locked(&dev_priv->dpio_lock));
- spin_lock_irqsave(&dev_priv->dpio_lock, flags);
if (wait_for_atomic_us((I915_READ(DPIO_PKT) & DPIO_BUSY) == 0, 100)) {
DRM_ERROR("DPIO idle wait timed out\n");
- goto out_unlock;
+ return 0;
}
I915_WRITE(DPIO_REG, reg);
@@ -430,24 +428,20 @@
DPIO_BYTE);
if (wait_for_atomic_us((I915_READ(DPIO_PKT) & DPIO_BUSY) == 0, 100)) {
DRM_ERROR("DPIO read wait timed out\n");
- goto out_unlock;
+ return 0;
}
- val = I915_READ(DPIO_DATA);
-out_unlock:
- spin_unlock_irqrestore(&dev_priv->dpio_lock, flags);
- return val;
+ return I915_READ(DPIO_DATA);
}
static void intel_dpio_write(struct drm_i915_private *dev_priv, int reg,
u32 val)
{
- unsigned long flags;
+ WARN_ON(!mutex_is_locked(&dev_priv->dpio_lock));
- spin_lock_irqsave(&dev_priv->dpio_lock, flags);
if (wait_for_atomic_us((I915_READ(DPIO_PKT) & DPIO_BUSY) == 0, 100)) {
DRM_ERROR("DPIO idle wait timed out\n");
- goto out_unlock;
+ return;
}
I915_WRITE(DPIO_DATA, val);
@@ -456,9 +450,6 @@
DPIO_BYTE);
if (wait_for_atomic_us((I915_READ(DPIO_PKT) & DPIO_BUSY) == 0, 100))
DRM_ERROR("DPIO write wait timed out\n");
-
-out_unlock:
- spin_unlock_irqrestore(&dev_priv->dpio_lock, flags);
}
static void vlv_init_dpio(struct drm_device *dev)
@@ -1455,13 +1446,12 @@
static void
intel_sbi_write(struct drm_i915_private *dev_priv, u16 reg, u32 value)
{
- unsigned long flags;
+ WARN_ON(!mutex_is_locked(&dev_priv->dpio_lock));
- spin_lock_irqsave(&dev_priv->dpio_lock, flags);
if (wait_for((I915_READ(SBI_CTL_STAT) & SBI_BUSY) == 0,
100)) {
DRM_ERROR("timeout waiting for SBI to become ready\n");
- goto out_unlock;
+ return;
}
I915_WRITE(SBI_ADDR,
@@ -1475,24 +1465,19 @@
if (wait_for((I915_READ(SBI_CTL_STAT) & (SBI_BUSY | SBI_RESPONSE_FAIL)) == 0,
100)) {
DRM_ERROR("timeout waiting for SBI to complete write transaction\n");
- goto out_unlock;
+ return;
}
-
-out_unlock:
- spin_unlock_irqrestore(&dev_priv->dpio_lock, flags);
}
static u32
intel_sbi_read(struct drm_i915_private *dev_priv, u16 reg)
{
- unsigned long flags;
- u32 value = 0;
+ WARN_ON(!mutex_is_locked(&dev_priv->dpio_lock));
- spin_lock_irqsave(&dev_priv->dpio_lock, flags);
if (wait_for((I915_READ(SBI_CTL_STAT) & SBI_BUSY) == 0,
100)) {
DRM_ERROR("timeout waiting for SBI to become ready\n");
- goto out_unlock;
+ return 0;
}
I915_WRITE(SBI_ADDR,
@@ -1504,14 +1489,10 @@
if (wait_for((I915_READ(SBI_CTL_STAT) & (SBI_BUSY | SBI_RESPONSE_FAIL)) == 0,
100)) {
DRM_ERROR("timeout waiting for SBI to complete read transaction\n");
- goto out_unlock;
+ return 0;
}
- value = I915_READ(SBI_DATA);
-
-out_unlock:
- spin_unlock_irqrestore(&dev_priv->dpio_lock, flags);
- return value;
+ return I915_READ(SBI_DATA);
}
/**
@@ -2924,6 +2905,8 @@
u32 divsel, phaseinc, auxdiv, phasedir = 0;
u32 temp;
+ mutex_lock(&dev_priv->dpio_lock);
+
/* It is necessary to ungate the pixclk gate prior to programming
* the divisors, and gate it back when it is done.
*/
@@ -3005,6 +2988,8 @@
udelay(24);
I915_WRITE(PIXCLK_GATE, PIXCLK_GATE_UNGATE);
+
+ mutex_unlock(&dev_priv->dpio_lock);
}
/*
@@ -4222,6 +4207,8 @@
bool is_sdvo;
u32 temp;
+ mutex_lock(&dev_priv->dpio_lock);
+
is_sdvo = intel_pipe_has_type(crtc, INTEL_OUTPUT_SDVO) ||
intel_pipe_has_type(crtc, INTEL_OUTPUT_HDMI);
@@ -4305,6 +4292,8 @@
temp |= (1 << 21);
intel_dpio_write(dev_priv, DPIO_DATA_CHANNEL2, temp);
}
+
+ mutex_unlock(&dev_priv->dpio_lock);
}
static void i9xx_update_pll(struct drm_crtc *crtc,