dmaengine: shdma: Fix SH_DMAC_MAX_CHANNELS handling

Fix the shdma.c handing of SH_DMAC_MAX_CHANNELS
to avoid overwriting the chan_irq[] and chan_flag[]
arrays in the case of pdata->channel_num is larger
than SH_DMAC_MAX_CHANNELS.

With this patch applied up to SH_DMAC_MAX_CHANNELS
will be used by the shdma.c driver. If more channels
are available in the platform data the user will
be notified on the console.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 23 insertions, 8 deletions

diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c
index 3391b157d057..636e40925b16 100644
--- a/drivers/dma/shdma.c
+++ b/drivers/dma/shdma.c
@@ -1083,7 +1083,7 @@ static int __init sh_dmae_probe(struct platform_device *pdev)
         unsigned long irqflags = IRQF_DISABLED,
                 chan_flag[SH_DMAC_MAX_CHANNELS] = {};
         int errirq, chan_irq[SH_DMAC_MAX_CHANNELS];
-        int err, i, irq_cnt = 0, irqres = 0;
+        int err, i, irq_cnt = 0, irqres = 0, irq_cap = 0;
         struct sh_dmae_device *shdev;
         struct resource *chan, *dmars, *errirq_res, *chanirq_res;
 
@@ -1208,8 +1208,13 @@ static int __init sh_dmae_probe(struct platform_device *pdev)
             !platform_get_resource(pdev, IORESOURCE_IRQ, 1)) {
                 /* Special case - all multiplexed */
                 for (; irq_cnt < pdata->channel_num; irq_cnt++) {
-                        chan_irq[irq_cnt] = chanirq_res->start;
-                        chan_flag[irq_cnt] = IRQF_SHARED;
+                        if (irq_cnt < SH_DMAC_MAX_CHANNELS) {
+                                chan_irq[irq_cnt] = chanirq_res->start;
+                                chan_flag[irq_cnt] = IRQF_SHARED;
+                        } else {
+                                irq_cap = 1;
+                                break;
+                        }
                 }
         } else {
                 do {
@@ -1223,22 +1228,32 @@ static int __init sh_dmae_probe(struct platform_device *pdev)
                                         "Found IRQ %d for channel %d\n",
                                         i, irq_cnt);
                                 chan_irq[irq_cnt++] = i;
+
+                                if (irq_cnt >= SH_DMAC_MAX_CHANNELS)
+                                        break;
+                        }
+
+                        if (irq_cnt >= SH_DMAC_MAX_CHANNELS) {
+                                irq_cap = 1;
+                                break;
                         }
                         chanirq_res = platform_get_resource(pdev,
                                                 IORESOURCE_IRQ, ++irqres);
                 } while (irq_cnt < pdata->channel_num && chanirq_res);
         }
 
-        if (irq_cnt < pdata->channel_num)
-                goto eirqres;
-
         /* Create DMA Channel */
-        for (i = 0; i < pdata->channel_num; i++) {
+        for (i = 0; i < irq_cnt; i++) {
                 err = sh_dmae_chan_probe(shdev, i, chan_irq[i], chan_flag[i]);
                 if (err)
                         goto chan_probe_err;
         }
 
+        if (irq_cap)
+                dev_notice(&pdev->dev, "Attempting to register %d DMA "
+                           "channels when a maximum of %d are supported.\n",
+                           pdata->channel_num, SH_DMAC_MAX_CHANNELS);
+
         pm_runtime_put(&pdev->dev);
 
         platform_set_drvdata(pdev, shdev);
@@ -1248,7 +1263,7 @@ static int __init sh_dmae_probe(struct platform_device *pdev)
 
 chan_probe_err:
         sh_dmae_chan_remove(shdev);
-eirqres:
+
 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_ARCH_SHMOBILE)
         free_irq(errirq, shdev);
 eirq_err: