PNP: don't fail device init if no DMA channel available

Most drivers for devices supporting ISA DMA can operate without DMA as well
(falling back zo PIO).  Thus it seems inappropriate for PNP to fail device
initialization in case none of the possible DMA channels are available.
Instead, it should be left to the driver to decide what to do if
request_dma() fails.

The patch at once adjusts the code to account for the fact that
pnp_assign_dma() now doesn't need to report failure anymore.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Cc: Adam Belay <ambx1@neo.rr.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/pnp/manager.c

@@ -161,7 +161,7 @@ static int pnp_assign_irq(struct pnp_dev *dev, struct pnp_irq *rule, int idx)
 	return 0;
 }
 
-static int pnp_assign_dma(struct pnp_dev *dev, struct pnp_dma *rule, int idx)
+static void pnp_assign_dma(struct pnp_dev *dev, struct pnp_dma *rule, int idx)
 {
 	resource_size_t *start, *end;
 	unsigned long *flags;
@@ -173,15 +173,14 @@ static int pnp_assign_dma(struct pnp_dev *dev, struct pnp_dma *rule, int idx)
 	};
 
 	if (idx >= PNP_MAX_DMA) {
-		pnp_err
-		    ("More than 2 dmas is incompatible with pnp specifications.");
-		/* pretend we were successful so at least the manager won't try again */
-		return 1;
+		pnp_err("More than 2 dmas is incompatible with pnp "
+			"specifications.");
+		return;
 	}
 
 	/* check if this resource has been manually set, if so skip */
 	if (!(dev->res.dma_resource[idx].flags & IORESOURCE_AUTO))
-		return 1;
+		return;
 
 	start = &dev->res.dma_resource[idx].start;
 	end = &dev->res.dma_resource[idx].end;
@@ -191,19 +190,17 @@ static int pnp_assign_dma(struct pnp_dev *dev, struct pnp_dma *rule, int idx)
 	*flags |= rule->flags | IORESOURCE_DMA;
 	*flags &= ~IORESOURCE_UNSET;
 
-	if (!rule->map) {
-		*flags |= IORESOURCE_DISABLED;
-		return 1;	/* skip disabled resource requests */
-	}
-
 	for (i = 0; i < 8; i++) {
 		if (rule->map & (1 << xtab[i])) {
 			*start = *end = xtab[i];
 			if (pnp_check_dma(dev, idx))
-				return 1;
+				return;
 		}
 	}
-	return 0;
+#ifdef MAX_DMA_CHANNELS
+	*start = *end = MAX_DMA_CHANNELS;
+#endif
+	*flags |= IORESOURCE_UNSET | IORESOURCE_DISABLED;
 }
 
 /**
@@ -330,8 +327,7 @@ static int pnp_assign_resources(struct pnp_dev *dev, int depnum)
 			irq = irq->next;
 		}
 		while (dma) {
-			if (!pnp_assign_dma(dev, dma, ndma))
-				goto fail;
+			pnp_assign_dma(dev, dma, ndma);
 			ndma++;
 			dma = dma->next;
 		}
@@ -367,8 +363,7 @@ static int pnp_assign_resources(struct pnp_dev *dev, int depnum)
 			irq = irq->next;
 		}
 		while (dma) {
-			if (!pnp_assign_dma(dev, dma, ndma))
-				goto fail;
+			pnp_assign_dma(dev, dma, ndma);
 			ndma++;
 			dma = dma->next;
 		}