[patch 2.6.0-test9] fix "generic dma" implementation bugs

From: David Brownell
Date: Wed Oct 29 2003 - 16:52:09 EST

This should fix some arch-specific problems with the "generic DMA"
API implementations of dma_supported() and dma_set_mask():

- dma_set_mask():
* Removes pointless clones that were used on arm, i386,
ia64, mips, and parisc
* Also removed PCI-specific "asm-generic" version
* Replaces them with a truly generic implementation that
doesn't needlessly BUG() with non-PCI devices
* Adds an ARCH_HAS_* hook to cope with sparc64-only
restrictions (for ali5451 pci audio hardware);
sparc64 retains a BUG() for non-pci hardware.
- dma_supported():
* Removes broken versions from arm, i386, mips; the
broken versions never actually compared the two
masks they were specified to compare:
+ arm only verified there was a device mask
+ i386/mips didn't even do that much
* Also removed PCI-specific "asm-generic" version
* Replaces them with a generic implementation that
+ doesn't needlessly BUG() with non-PCI devices
+ actually compares the two masks (bit-wise)
* Adds an ARCH_HAS_* hook to handle ia64 and parisc,
which already have their own fancy implementations

Sanity tested on x86/pc and ARM/PXA.

It's unfortunate that the arch-specific BUG() behavior only
started getting reported recently (test7?); and particularly
that the previous dma_supported() was so broken even on i386.
In consequence, it's not quite clear what bugs are being
hidden by the bogus masking.

- Dave

--- 1.1/include/linux/dma-mapping.h Sat Dec 21 20:37:05 2002
+++ edited/include/linux/dma-mapping.h Tue Oct 28 10:56:19 2003
@@ -12,6 +12,37 @@

#include <asm/dma-mapping.h>

+#ifndef ARCH_HAS_DMA_SUPPORTED
+/*
+ * Returns true iff the device can support those DMA address bits on this
+ * system. For example: to see if it can do DMA with any 64 bit address
+ * you could pass ~(u64)0 as the mask; to test for 24 bit bus mastering
+ * address support, pass 0x00ffffff as the mask.
+ */
+static inline int
+dma_supported(struct device *dev, u64 mask)
+{
+ return dev && dev->dma_mask && (mask & ~*dev->dma_mask) == 0;
+}
+#endif
+
+#ifndef ARCH_HAS_DMA_SET_MASK
+/*
+ * Changes a driver's DMA mask; this can sometimes have side-effects.
+ * Only the lowest level of the driver stack may use this call;
+ * virtualized devices (higher in the stack) must never use this,
+ * since they don't directly control the hardware or DMA.
+ */
+static inline int
+dma_set_mask(struct device *dev, u64 mask)
+{
+ if (!dma_supported(dev, mask))
+ return -EIO;
+ *dev->dma_mask = mask;
+ return 0;
+}
+#endif
+
#endif


--- 1.7/include/asm-arm/dma-mapping.h Wed Aug 13 16:46:20 2003
+++ edited/include/asm-arm/dma-mapping.h Sun Oct 26 11:23:01 2003
@@ -39,27 +39,6 @@
#define dmadev_is_sa1111(dev) (0)
#endif

-/*
- * Return whether the given device DMA address mask can be supported
- * properly. For example, if your device can only drive the low 24-bits
- * during bus mastering, then you would pass 0x00ffffff as the mask
- * to this function.
- */
-static inline int dma_supported(struct device *dev, u64 mask)
-{
- return dev->dma_mask && *dev->dma_mask != 0;
-}
-
-static inline int dma_set_mask(struct device *dev, u64 dma_mask)
-{
- if (!dev->dma_mask || !dma_supported(dev, dma_mask))
- return -EIO;
-
- *dev->dma_mask = dma_mask;
-
- return 0;
-}
-
static inline int dma_get_cache_alignment(void)
{
return 32;
--- 1.4/include/asm-generic/dma-mapping.h Mon Jan 13 14:37:47 2003
+++ edited/include/asm-generic/dma-mapping.h Sun Oct 26 11:20:02 2003
@@ -13,22 +13,6 @@
/* need struct page definitions */
#include <linux/mm.h>

-static inline int
-dma_supported(struct device *dev, u64 mask)
-{
- BUG_ON(dev->bus != &pci_bus_type);
-
- return pci_dma_supported(to_pci_dev(dev), mask);
-}
-
-static inline int
-dma_set_mask(struct device *dev, u64 dma_mask)
-{
- BUG_ON(dev->bus != &pci_bus_type);
-
- return pci_set_dma_mask(to_pci_dev(dev), dma_mask);
-}
-
static inline void *
dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
int flag)
--- 1.2/include/asm-i386/dma-mapping.h Mon Jan 13 08:28:47 2003
+++ edited/include/asm-i386/dma-mapping.h Sun Oct 26 11:23:23 2003
@@ -93,31 +93,6 @@
}

static inline int
-dma_supported(struct device *dev, u64 mask)
-{
- /*
- * we fall back to GFP_DMA when the mask isn't all 1s,
- * so we can't guarantee allocations that must be
- * within a tighter range than GFP_DMA..
- */
- if(mask < 0x00ffffff)
- return 0;
-
- return 1;
-}
-
-static inline int
-dma_set_mask(struct device *dev, u64 mask)
-{
- if(!dev->dma_mask || !dma_supported(dev, mask))
- return -EIO;
-
- *dev->dma_mask = mask;
-
- return 0;
-}
-
-static inline int
dma_get_cache_alignment(void)
{
/* no easy way to get cache size on all x86, so return the
--- 1.2/include/asm-ia64/dma-mapping.h Sat May 10 02:28:47 2003
+++ edited/include/asm-ia64/dma-mapping.h Sun Oct 26 11:25:01 2003
@@ -31,15 +31,7 @@
dma_sync_single(dev, dma_handle, size, dir)

#define dma_supported platform_dma_supported
-
-static inline int
-dma_set_mask (struct device *dev, u64 mask)
-{
- if (!dev->dma_mask || !dma_supported(dev, mask))
- return -EIO;
- *dev->dma_mask = mask;
- return 0;
-}
+#define ARCH_HAS_DMA_SUPPORTED

static inline int
dma_get_cache_alignment (void)
--- 1.2/include/asm-mips/dma-mapping.h Mon Jul 28 04:57:50 2003
+++ edited/include/asm-mips/dma-mapping.h Sun Oct 26 11:25:57 2003
@@ -181,31 +181,6 @@
#endif /* CONFIG_MAPPED_DMA_IO */

static inline int
-dma_supported(struct device *dev, u64 mask)
-{
- /*
- * we fall back to GFP_DMA when the mask isn't all 1s,
- * so we can't guarantee allocations that must be
- * within a tighter range than GFP_DMA..
- */
- if (mask < 0x00ffffff)
- return 0;
-
- return 1;
-}
-
-static inline int
-dma_set_mask(struct device *dev, u64 mask)
-{
- if(!dev->dma_mask || !dma_supported(dev, mask))
- return -EIO;
-
- *dev->dma_mask = mask;
-
- return 0;
-}
-
-static inline int
dma_get_cache_alignment(void)
{
/* XXX Largest on any MIPS */
--- 1.4/include/asm-parisc/dma-mapping.h Sat Sep 27 14:43:44 2003
+++ edited/include/asm-parisc/dma-mapping.h Sun Oct 26 11:26:19 2003
@@ -142,21 +142,11 @@
hppa_dma_ops->dma_sync_sg(dev, sg, nelems, direction);
}

+#define ARCH_HAS_DMA_SUPPORTED
static inline int
dma_supported(struct device *dev, u64 mask)
{
return hppa_dma_ops->dma_supported(dev, mask);
-}
-
-static inline int
-dma_set_mask(struct device *dev, u64 mask)
-{
- if(!dev->dma_mask || !dma_supported(dev, mask))
- return -EIO;
-
- *dev->dma_mask = mask;
-
- return 0;
}

static inline int
--- 1.2/include/asm-sparc64/dma-mapping.h Wed Jul 23 00:04:55 2003
+++ edited/include/asm-sparc64/dma-mapping.h Tue Oct 28 11:23:39 2003
@@ -2,4 +2,14 @@

#ifdef CONFIG_PCI
#include <asm-generic/dma-mapping.h>
+
+#define ARCH_HAS_DMA_SET_MASK
+static inline int
+dma_set_mask(struct device *dev, u64 dma_mask)
+{
+ BUG_ON(dev->bus != &pci_bus_type);
+
+ return pci_set_dma_mask(to_pci_dev(dev), dma_mask);
+}
+
#endif