i.MX31: fix framebuffer locking regressions

Recent framebuffer locking patches first made affected systems unbootable,
then the dead-lock has been fixed but as of 2.6.31-rc4 the framebuffer on
mx3 machines doesn't work. Fix this.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/video/mx3fb.c

@@ -669,7 +669,8 @@ static uint32_t bpp_to_pixfmt(int bpp)
 }
 
 static int mx3fb_blank(int blank, struct fb_info *fbi);
-static int mx3fb_map_video_memory(struct fb_info *fbi, unsigned int mem_len);
+static int mx3fb_map_video_memory(struct fb_info *fbi, unsigned int mem_len,
+				  bool lock);
 static int mx3fb_unmap_video_memory(struct fb_info *fbi);
 
 /**
@@ -711,12 +712,7 @@ static void mx3fb_dma_done(void *arg)
 	complete(&mx3_fbi->flip_cmpl);
 }
 
-/**
- * mx3fb_set_par() - set framebuffer parameters and change the operating mode.
- * @fbi:	framebuffer information pointer.
- * @return:	0 on success or negative error code on failure.
- */
-static int mx3fb_set_par(struct fb_info *fbi)
+static int __set_par(struct fb_info *fbi, bool lock)
 {
 	u32 mem_len;
 	struct ipu_di_signal_cfg sig_cfg;
@@ -727,10 +723,6 @@ static int mx3fb_set_par(struct fb_info *fbi)
 	struct idmac_video_param *video = &ichan->params.video;
 	struct scatterlist *sg = mx3_fbi->sg;
 
-	dev_dbg(mx3fb->dev, "%s [%c]\n", __func__, list_empty(&ichan->queue) ? '-' : '+');
-
-	mutex_lock(&mx3_fbi->mutex);
-
 	/* Total cleanup */
 	if (mx3_fbi->txd)
 		sdc_disable_channel(mx3_fbi);
@@ -742,10 +734,8 @@ static int mx3fb_set_par(struct fb_info *fbi)
 		if (fbi->fix.smem_start)
 			mx3fb_unmap_video_memory(fbi);
 
-		if (mx3fb_map_video_memory(fbi, mem_len) < 0) {
-			mutex_unlock(&mx3_fbi->mutex);
+		if (mx3fb_map_video_memory(fbi, mem_len, lock) < 0)
 			return -ENOMEM;
-		}
 	}
 
 	sg_init_table(&sg[0], 1);
@@ -791,7 +781,6 @@ static int mx3fb_set_par(struct fb_info *fbi)
 				   fbi->var.vsync_len,
 				   fbi->var.lower_margin +
 				   fbi->var.vsync_len, sig_cfg) != 0) {
-			mutex_unlock(&mx3_fbi->mutex);
 			dev_err(fbi->device,
 				"mx3fb: Error initializing panel.\n");
 			return -EINVAL;
@@ -810,9 +799,30 @@ static int mx3fb_set_par(struct fb_info *fbi)
 	if (mx3_fbi->blank == FB_BLANK_UNBLANK)
 		sdc_enable_channel(mx3_fbi);
 
+	return 0;
+}
+
+/**
+ * mx3fb_set_par() - set framebuffer parameters and change the operating mode.
+ * @fbi:	framebuffer information pointer.
+ * @return:	0 on success or negative error code on failure.
+ */
+static int mx3fb_set_par(struct fb_info *fbi)
+{
+	struct mx3fb_info *mx3_fbi = fbi->par;
+	struct mx3fb_data *mx3fb = mx3_fbi->mx3fb;
+	struct idmac_channel *ichan = mx3_fbi->idmac_channel;
+	int ret;
+
+	dev_dbg(mx3fb->dev, "%s [%c]\n", __func__, list_empty(&ichan->queue) ? '-' : '+');
+
+	mutex_lock(&mx3_fbi->mutex);
+
+	ret = __set_par(fbi, true);
+
 	mutex_unlock(&mx3_fbi->mutex);
 
-	return 0;
+	return ret;
 }
 
 /**
@@ -966,21 +976,11 @@ static int mx3fb_setcolreg(unsigned int regno, unsigned int red,
 	return ret;
 }
 
-/**
- * mx3fb_blank() - blank the display.
- */
-static int mx3fb_blank(int blank, struct fb_info *fbi)
+static void __blank(int blank, struct fb_info *fbi)
 {
 	struct mx3fb_info *mx3_fbi = fbi->par;
 	struct mx3fb_data *mx3fb = mx3_fbi->mx3fb;
 
-	dev_dbg(fbi->device, "%s, blank = %d, base %p, len %u\n", __func__,
-		blank, fbi->screen_base, fbi->fix.smem_len);
-
-	if (mx3_fbi->blank == blank)
-		return 0;
-
-	mutex_lock(&mx3_fbi->mutex);
 	mx3_fbi->blank = blank;
 
 	switch (blank) {
@@ -999,6 +999,23 @@ static int mx3fb_blank(int blank, struct fb_info *fbi)
 		sdc_set_brightness(mx3fb, mx3fb->backlight_level);
 		break;
 	}
+}
+
+/**
+ * mx3fb_blank() - blank the display.
+ */
+static int mx3fb_blank(int blank, struct fb_info *fbi)
+{
+	struct mx3fb_info *mx3_fbi = fbi->par;
+
+	dev_dbg(fbi->device, "%s, blank = %d, base %p, len %u\n", __func__,
+		blank, fbi->screen_base, fbi->fix.smem_len);
+
+	if (mx3_fbi->blank == blank)
+		return 0;
+
+	mutex_lock(&mx3_fbi->mutex);
+	__blank(blank, fbi);
 	mutex_unlock(&mx3_fbi->mutex);
 
 	return 0;
@@ -1198,6 +1215,7 @@ static int mx3fb_resume(struct platform_device *pdev)
  * mx3fb_map_video_memory() - allocates the DRAM memory for the frame buffer.
  * @fbi:	framebuffer information pointer
  * @mem_len:	length of mapped memory
+ * @lock:	do not lock during initialisation
  * @return:	Error code indicating success or failure
  *
  * This buffer is remapped into a non-cached, non-buffered, memory region to
@@ -1205,7 +1223,8 @@ static int mx3fb_resume(struct platform_device *pdev)
  * area is remapped, all virtual memory access to the video memory should occur
  * at the new region.
  */
-static int mx3fb_map_video_memory(struct fb_info *fbi, unsigned int mem_len)
+static int mx3fb_map_video_memory(struct fb_info *fbi, unsigned int mem_len,
+				  bool lock)
 {
 	int retval = 0;
 	dma_addr_t addr;
@@ -1221,10 +1240,12 @@ static int mx3fb_map_video_memory(struct fb_info *fbi, unsigned int mem_len)
 		goto err0;
 	}
 
-	mutex_lock(&fbi->mm_lock);
+	if (lock)
+		mutex_lock(&fbi->mm_lock);
 	fbi->fix.smem_start = addr;
 	fbi->fix.smem_len = mem_len;
-	mutex_unlock(&fbi->mm_lock);
+	if (lock)
+		mutex_unlock(&fbi->mm_lock);
 
 	dev_dbg(fbi->device, "allocated fb @ p=0x%08x, v=0x%p, size=%d.\n",
 		(uint32_t) fbi->fix.smem_start, fbi->screen_base, fbi->fix.smem_len);
@@ -1365,6 +1386,11 @@ static int init_fb_chan(struct mx3fb_data *mx3fb, struct idmac_channel *ichan)
 	init_completion(&mx3fbi->flip_cmpl);
 	disable_irq(ichan->eof_irq);
 	dev_dbg(mx3fb->dev, "disabling irq %d\n", ichan->eof_irq);
+	ret = __set_par(fbi, false);
+	if (ret < 0)
+		goto esetpar;
+
+	__blank(FB_BLANK_UNBLANK, fbi);
 
 	dev_info(dev, "registered, using mode %s\n", fb_mode);