[ARM] 3601/1: i.MX/MX1 DMA error handling for signaled channels only

Patch from Pavel Pisa

There has been bug, that dma_err_handler() touches even
channels not signaling error condition.

Problem noticed by Andrea Paterniani.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 45 insertions, 28 deletions

diff --git a/arch/arm/mach-imx/dma.c b/arch/arm/mach-imx/dma.c
index 4ca51dcf13ac..36578871ecc8 100644
--- a/arch/arm/mach-imx/dma.c
+++ b/arch/arm/mach-imx/dma.c
@@ -15,6 +15,9 @@
  *             Changed to support scatter gather DMA
  *             by taking Russell's code from RiscPC
  *
+ *  2006-05-31 Pavel Pisa <pisa@cmp.felk.cvut.cz>
+ *             Corrected error handling code.
+ *
  */
 
 #undef DEBUG
@@ -277,7 +280,7 @@ imx_dma_setup_sg(imx_dmach_t dma_ch,
 int
 imx_dma_setup_handlers(imx_dmach_t dma_ch,
                        void (*irq_handler) (int, void *, struct pt_regs *),
-                       void (*err_handler) (int, void *, struct pt_regs *),
+                       void (*err_handler) (int, void *, struct pt_regs *, int),
                        void *data)
 {
         struct imx_dma_channel *imxdma = &imx_dma_channels[dma_ch];
@@ -463,43 +466,53 @@ static irqreturn_t dma_err_handler(int irq, void *dev_id, struct pt_regs *regs)
         int i, disr = DISR;
         struct imx_dma_channel *channel;
         unsigned int err_mask = DBTOSR | DRTOSR | DSESR | DBOSR;
+        int errcode;
 
-        DISR = disr;
+        DISR = disr & err_mask;
         for (i = 0; i < IMX_DMA_CHANNELS; i++) {
-                channel = &imx_dma_channels[i];
-
-                if ((err_mask & 1 << i) && channel->name
-                    && channel->err_handler) {
-                        channel->err_handler(i, channel->data, regs);
+                if(!(err_mask & (1 << i)))
                         continue;
-                }
-
-                imx_dma_channels[i].sg = NULL;
+                channel = &imx_dma_channels[i];
+                errcode = 0;
 
                 if (DBTOSR & (1 << i)) {
-                        printk(KERN_WARNING
-                               "Burst timeout on channel %d (%s)\n",
-                               i, channel->name);
-                        DBTOSR |= (1 << i);
+                        DBTOSR = (1 << i);
+                        errcode |= IMX_DMA_ERR_BURST;
                 }
                 if (DRTOSR & (1 << i)) {
-                        printk(KERN_WARNING
-                               "Request timeout on channel %d (%s)\n",
-                               i, channel->name);
-                        DRTOSR |= (1 << i);
+                        DRTOSR = (1 << i);
+                        errcode |= IMX_DMA_ERR_REQUEST;
                 }
                 if (DSESR & (1 << i)) {
-                        printk(KERN_WARNING
-                               "Transfer timeout on channel %d (%s)\n",
-                               i, channel->name);
-                        DSESR |= (1 << i);
+                        DSESR = (1 << i);
+                        errcode |= IMX_DMA_ERR_TRANSFER;
                 }
                 if (DBOSR & (1 << i)) {
-                        printk(KERN_WARNING
-                               "Buffer overflow timeout on channel %d (%s)\n",
-                               i, channel->name);
-                        DBOSR |= (1 << i);
+                        DBOSR = (1 << i);
+                        errcode |= IMX_DMA_ERR_BUFFER;
                 }
+
+                /*
+                 * The cleaning of @sg field would be questionable
+                 * there, because its value can help to compute
+                 * remaining/transfered bytes count in the handler
+                 */
+                /*imx_dma_channels[i].sg = NULL;*/
+
+                if (channel->name && channel->err_handler) {
+                        channel->err_handler(i, channel->data, regs, errcode);
+                        continue;
+                }
+
+                imx_dma_channels[i].sg = NULL;
+
+                printk(KERN_WARNING
+                       "DMA timeout on channel %d (%s) -%s%s%s%s\n",
+                       i, channel->name,
+                       errcode&IMX_DMA_ERR_BURST?    " burst":"",
+                       errcode&IMX_DMA_ERR_REQUEST?  " request":"",
+                       errcode&IMX_DMA_ERR_TRANSFER? " transfer":"",
+                       errcode&IMX_DMA_ERR_BUFFER?   " buffer":"");
         }
         return IRQ_HANDLED;
 }
diff --git a/include/asm-arm/arch-imx/imx-dma.h b/include/asm-arm/arch-imx/imx-dma.h
index f2063c1d610d..599f03e5a9ef 100644
--- a/include/asm-arm/arch-imx/imx-dma.h
+++ b/include/asm-arm/arch-imx/imx-dma.h
@@ -46,7 +46,7 @@
 struct imx_dma_channel {
         const char *name;
         void (*irq_handler) (int, void *, struct pt_regs *);
-        void (*err_handler) (int, void *, struct pt_regs *);
+        void (*err_handler) (int, void *, struct pt_regs *, int errcode);
         void *data;
         dmamode_t  dma_mode;
         struct scatterlist *sg;
@@ -58,6 +58,10 @@ struct imx_dma_channel {
 
 extern struct imx_dma_channel imx_dma_channels[IMX_DMA_CHANNELS];
 
+#define IMX_DMA_ERR_BURST     1
+#define IMX_DMA_ERR_REQUEST   2
+#define IMX_DMA_ERR_TRANSFER  4
+#define IMX_DMA_ERR_BUFFER    8
 
 /* The type to distinguish channel numbers parameter from ordinal int type */
 typedef int imx_dmach_t;
@@ -74,7 +78,7 @@ imx_dma_setup_sg(imx_dmach_t dma_ch,
 int
 imx_dma_setup_handlers(imx_dmach_t dma_ch,
                 void (*irq_handler) (int, void *, struct pt_regs *),
-                void (*err_handler) (int, void *, struct pt_regs *), void *data);
+                void (*err_handler) (int, void *, struct pt_regs *, int), void *data);
 
 void imx_dma_enable(imx_dmach_t dma_ch);