gma500: frame buffer locking

If we are the console then a printk can hit us with a spin lock held (and
in fact the kernel will do its best to take the console printing lock).

In that case we cannot politely sleep when synching after an accelerated op
but must behave obnoxiously to be sure of getting the bits out.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/gma500/accel_2d.c

@@ -111,8 +111,9 @@ static int psbfb_2d_submit(struct drm_psb_private *dev_priv, uint32_t *cmdbuf,
 	int ret = 0;
 	int i;
 	unsigned submit_size;
+	unsigned long flags;
 
-	mutex_lock(&dev_priv->mutex_2d);
+	spin_lock_irqsave(&dev_priv->lock_2d, flags);
 	while (size > 0) {
 		submit_size = (size < 0x60) ? size : 0x60;
 		size -= submit_size;
@@ -127,7 +128,7 @@ static int psbfb_2d_submit(struct drm_psb_private *dev_priv, uint32_t *cmdbuf,
 
 		(void)PSB_RSGX32(PSB_SGX_2D_SLAVE_PORT + i - 4);
 	}
-	mutex_unlock(&dev_priv->mutex_2d);
+	spin_unlock_irqrestore(&dev_priv->lock_2d, flags);
 	return ret;
 }
 
@@ -327,8 +328,9 @@ int psbfb_sync(struct fb_info *info)
 	struct drm_psb_private *dev_priv = dev->dev_private;
 	unsigned long _end = jiffies + DRM_HZ;
 	int busy = 0;
+	unsigned long flags;
 
-	mutex_lock(&dev_priv->mutex_2d);
+	spin_lock_irqsave(&dev_priv->lock_2d, flags);
 	/*
 	 * First idle the 2D engine.
 	 */
@@ -357,6 +359,6 @@ int psbfb_sync(struct fb_info *info)
 					_PSB_C2B_STATUS_BUSY) != 0);
 
 out:
-	mutex_unlock(&dev_priv->mutex_2d);
+	spin_unlock_irqrestore(&dev_priv->lock_2d, flags);
 	return (busy) ? -EBUSY : 0;
 }

drivers/gpu/drm/gma500/psb_drv.c

@@ -186,7 +186,7 @@ static int psb_do_init(struct drm_device *dev)
 
 
 	spin_lock_init(&dev_priv->irqmask_lock);
-	mutex_init(&dev_priv->mutex_2d);
+	spin_lock_init(&dev_priv->lock_2d);
 
 	PSB_WSGX32(0x00000000, PSB_CR_BIF_BANK0);
 	PSB_WSGX32(0x00000000, PSB_CR_BIF_BANK1);

drivers/gpu/drm/gma500/psb_drv.h

@@ -606,7 +606,7 @@ struct drm_psb_private {
 	void *fbdev;
 
 	/* 2D acceleration */
-	struct mutex mutex_2d;
+	spinlock_t lock_2d;
 };