[PATCH/RFC] PVR2 DMA fix

[Adrian M. <ad...@ne...>]

The code for PVR2 DMA in the kernel is currently completely broken at
both hardware handling and algorithmic levels and more than likely to
cash a fatal crash if used.

This patch fixes the code and it seems to work well. I know it is not up
to the standards required to go to mainline yet, but any commentary on
it would be helpful.

Signed-off by Adrian McMenamin <ad...@mc...>

--- a/arch/sh/drivers/dma/dma-pvr2.c
+++ b/arch/sh/drivers/dma/dma-pvr2.c
@@ -18,23 +18,14 @@
 #include <asm/dma.h>
 #include <asm/io.h>
 
-static unsigned int xfer_complete;
-static int count;
-
 static irqreturn_t pvr2_dma_interrupt(int irq, void *dev_id)
 {
-	if (get_dma_residue(PVR2_CASCADE_CHAN)) {
-		printk(KERN_WARNING "DMA: SH DMAC did not complete transfer "
-		       "on channel %d, waiting..\n", PVR2_CASCADE_CHAN);
-		dma_wait_for_completion(PVR2_CASCADE_CHAN);
+	struct dma_channel *channel;
+	if (likely(!get_dma_residue(PVR2_CASCADE_CHAN))) {
+		channel = get_dma_channel(PVR2_CASCADE_CHAN);
+		wake_up(&channel->wait_queue);
 	}
 
-	if (count++ < 10)
-		pr_debug("Got a pvr2 dma interrupt for channel %d\n",
-			 irq - HW_EVENT_PVR2_DMA);
-
-	xfer_complete = 1;
-
 	return IRQ_HANDLED;
 }
 
@@ -42,15 +33,12 @@ static int pvr2_request_dma(struct dma_channel
*chan)
 {
 	if (ctrl_inl(PVR2_DMA_MODE) != 0)
 		return -EBUSY;
-
-	ctrl_outl(0, PVR2_DMA_LMMODE0);
-
 	return 0;
 }
 
 static int pvr2_get_dma_residue(struct dma_channel *chan)
 {
-	return xfer_complete == 0;
+	return ctrl_inl(PVR2_DMA_MODE);
 }
 
 static int pvr2_xfer_dma(struct dma_channel *chan)
@@ -58,11 +46,9 @@ static int pvr2_xfer_dma(struct dma_channel *chan)
 	if (chan->sar || !chan->dar)
 		return -EINVAL;
 
-	xfer_complete = 0;
-
 	ctrl_outl(chan->dar, PVR2_DMA_ADDR);
 	ctrl_outl(chan->count, PVR2_DMA_COUNT);
-	ctrl_outl(chan->mode & DMA_MODE_MASK, PVR2_DMA_MODE);
+	ctrl_outl(1, PVR2_DMA_MODE);
 
 	return 0;
 }

--- a/drivers/video/pvr2fb.c
+++ b/drivers/video/pvr2fb.c
@@ -677,11 +677,14 @@ static int pvr2_init_cable(void)
 static ssize_t pvr2fb_write(struct fb_info *info, const char *buf,
 			    size_t count, loff_t *ppos)
 {
-	unsigned long dst, start, end, len;
+	unsigned long dst, start, end, len, phys_dst;
 	unsigned int nr_pages;
 	struct page **pages;
 	int ret, i;
 
+	/* Bounds check */
+	if (*ppos > 0x2FFFFF) return -ENOSPC;
+
 	nr_pages = (count + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
 	pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
@@ -698,39 +701,57 @@ static ssize_t pvr2fb_write(struct fb_info *info,
const char *buf,
 		ret = -EINVAL;
 		goto out_unmap;
 	}
-
-	dma_configure_channel(shdma, 0x12c1);
+	
 
 	dst   = (unsigned long)fb_info->screen_base + *ppos;
 	start = (unsigned long)page_address(pages[0]);
-	end   = (unsigned long)page_address(pages[nr_pages]);
+	end   = (unsigned long)page_address(pages[nr_pages - 1]);
 	len   = nr_pages << PAGE_SHIFT;
+	if ((*ppos + len) > 0x2FFFFF)
+		len = 0x2FFFFF - *ppos;
+
+	/* transfer is via Tile Accelerator */
+	phys_dst = PHYSADDR(*ppos + 0x11000000);
+	if (phys_dst >= 0x11000000 && phys_dst <= 0x11FFFFE0){
+		ctrl_outl(0, PVR2_DMA_LMMODE0);
+		ctrl_outl(1, PVR2_DMA_LMMODE1);
+	}
+	else if (phys_dst >= 0x13000000 && phys_dst <= 0x13FFFFE0) {
+		ctrl_outl(1, PVR2_DMA_LMMODE0);
+		ctrl_outl(0, PVR2_DMA_LMMODE1);
+	}
+	else {
+		ctrl_outl(1, PVR2_DMA_LMMODE0);
+		ctrl_outl(1, PVR2_DMA_LMMODE1);
+	}
 
-	/* Half-assed contig check */
-	if (start + len == end) {
-		/* As we do this in one shot, it's either all or nothing.. */
-		if ((*ppos + len) > fb_info->fix.smem_len) {
-			ret = -ENOSPC;
-			goto out_unmap;
-		}
-
-		dma_write(shdma, start, 0, len);
-		dma_write(pvr2dma, 0, dst, len);
-		dma_wait_for_completion(pvr2dma);
+	if (start + len == end + (1 << PAGE_SHIFT)) {
+		ctrl_outl(0, PVR2_DMA_MODE);		/* DMA off for now */
+		ctrl_outl(0x12c0, 0xFFA0002C); 		/* set transfer flags to off */
+		ctrl_outl(start, 0xFFA00020);		/* set channel 2 start address */
+		ctrl_outl(len/32, 0xFFA00028);		/* chan2 dma is in 32 byte lumps */
+		ctrl_outl(0x12c1, 0xFFA0002C);		/* set flags to be ready to go */
+		ctrl_outl(phys_dst, PVR2_DMA_ADDR);	/* transfer is via the TA */
+		ctrl_outl(len, PVR2_DMA_COUNT);		
+		ctrl_outl(1, PVR2_DMA_MODE);		/* and go... */
+		dma_wait_for_completion(shdma);		/* sleep till we are done */
 
 		goto out;
 	}
 
 	/* Not contiguous, writeout per-page instead.. */
 	for (i = 0; i < nr_pages; i++, dst += PAGE_SIZE) {
-		if ((*ppos + (i << PAGE_SHIFT)) > fb_info->fix.smem_len) {
-			ret = -ENOSPC;
-			goto out_unmap;
-		}
-
-		dma_write_page(shdma, (unsigned long)page_address(pages[i]), 0);
-		dma_write_page(pvr2dma, 0, dst);
-		dma_wait_for_completion(pvr2dma);
+		if ((*ppos + (1 << PAGE_SHIFT)) > 0x2FFFFF)
+			break;
+		ctrl_outl(0, PVR2_DMA_MODE);
+		ctrl_outl(0x12c0, 0xFFA0002C);
+		ctrl_outl((unsigned long)page_address(pages[i]), 0xFFA00020);
+		ctrl_outl(len/32, 0xFFA00028);
+		ctrl_outl(0x12c1, 0xFFA0002C);
+		ctrl_outl(phys_dst, PVR2_DMA_ADDR);
+		ctrl_outl(1 << PAGE_SHIFT, PVR2_DMA_COUNT);
+		ctrl_outl(1, PVR2_DMA_MODE);
+		dma_wait_for_completion(shdma);
 	}
 
 out:
@@ -890,7 +911,7 @@ static int __init pvr2fb_dc_init(void)
 	pvr2_fix.mmio_start	= 0xa05f8000;	/* registers start here */
 	pvr2_fix.mmio_len	= 0x2000;
 
-	if (request_irq(HW_EVENT_VSYNC, pvr2fb_interrupt, 0,
+	if (request_irq(HW_EVENT_VSYNC, pvr2fb_interrupt, IRQF_SHARED,
 	                "pvr2 VBL handler", fb_info)) {
 		return -EBUSY;
 	}