diff mbox series

[RFC,1/5] dma/direct: turn ARCH_ZONE_DMA_BITS into a variable

Message ID 20191014183108.24804-2-nsaenzjulienne@suse.de (mailing list archive)
State New, archived
Headers show
Series ARM: Raspberry Pi 4 DMA support | expand

Commit Message

Nicolas Saenz Julienne Oct. 14, 2019, 6:31 p.m. UTC 
Some architectures, notably ARM, are interested in tweaking this
depending on their runtime DMA addressing limitations.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 arch/arm64/include/asm/page.h   |  2 --
 arch/arm64/mm/init.c            |  9 +++++++--
 arch/powerpc/include/asm/page.h |  9 ---------
 arch/powerpc/mm/mem.c           | 20 +++++++++++++++-----
 arch/s390/include/asm/page.h    |  2 --
 arch/s390/mm/init.c             |  1 +
 include/linux/dma-direct.h      |  2 ++
 kernel/dma/direct.c             | 13 ++++++-------
 8 files changed, 31 insertions(+), 27 deletions(-)

Comments

Christoph Hellwig Oct. 30, 2019, 9:49 p.m. UTC | #1 
On Mon, Oct 14, 2019 at 08:31:03PM +0200, Nicolas Saenz Julienne wrote:
> Some architectures, notably ARM, are interested in tweaking this
> depending on their runtime DMA addressing limitations.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

Do you want me to pick this up for the 5.5 dma-mapping tree, or do you
want me to wait for the rest to settle?
Nicolas Saenz Julienne Oct. 31, 2019, 10:30 a.m. UTC | #2 
On Wed, 2019-10-30 at 14:49 -0700, Christoph Hellwig wrote:
> On Mon, Oct 14, 2019 at 08:31:03PM +0200, Nicolas Saenz Julienne wrote:
> > Some architectures, notably ARM, are interested in tweaking this
> > depending on their runtime DMA addressing limitations.
> > 
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> 
> Do you want me to pick this up for the 5.5 dma-mapping tree, or do you
> want me to wait for the rest to settle?

I'd say take it, this will be ultimately needed once we push forward with ARM.
Christoph Hellwig Oct. 31, 2019, 1:38 p.m. UTC | #3 
On Thu, Oct 31, 2019 at 11:30:36AM +0100, Nicolas Saenz Julienne wrote:
> On Wed, 2019-10-30 at 14:49 -0700, Christoph Hellwig wrote:
> > On Mon, Oct 14, 2019 at 08:31:03PM +0200, Nicolas Saenz Julienne wrote:
> > > Some architectures, notably ARM, are interested in tweaking this
> > > depending on their runtime DMA addressing limitations.
> > > 
> > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > 
> > Do you want me to pick this up for the 5.5 dma-mapping tree, or do you
> > want me to wait for the rest to settle?
> 
> I'd say take it, this will be ultimately needed once we push forward with ARM.

Can you resend a version that applies against 5.4-rc?  The current one
has conflicts in the arm64 code.
Nicolas Saenz Julienne Oct. 31, 2019, 5:26 p.m. UTC | #4 
On Thu, 2019-10-31 at 06:38 -0700, Christoph Hellwig wrote:
> On Thu, Oct 31, 2019 at 11:30:36AM +0100, Nicolas Saenz Julienne wrote:
> > On Wed, 2019-10-30 at 14:49 -0700, Christoph Hellwig wrote:
> > > On Mon, Oct 14, 2019 at 08:31:03PM +0200, Nicolas Saenz Julienne wrote:
> > > > Some architectures, notably ARM, are interested in tweaking this
> > > > depending on their runtime DMA addressing limitations.
> > > > 
> > > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > > 
> > > Do you want me to pick this up for the 5.5 dma-mapping tree, or do you
> > > want me to wait for the rest to settle?
> > 
> > I'd say take it, this will be ultimately needed once we push forward with
> > ARM.
> 
> Can you resend a version that applies against 5.4-rc?  The current one
> has conflicts in the arm64 code.

Hi Catalin,
would you mind taking this patch on top of the arm64 ZONE_DMA series?

I tried to go though Christoph's tree but it ultimately clashes with the
ZONE_DMA series. It's simpler to apply it on top of your tree.

Regrads,
Nicolas
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index 7b8c98830101..d39ddb258a04 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -38,6 +38,4 @@  extern int pfn_valid(unsigned long);
 
 #include <asm-generic/getorder.h>
 
-#define ARCH_ZONE_DMA_BITS 30
-
 #endif
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 44f07fdf7a59..ddd6a6ce158e 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -20,6 +20,7 @@ 
 #include <linux/sort.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
+#include <linux/dma-direct.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-contiguous.h>
 #include <linux/efi.h>
@@ -41,6 +42,8 @@ 
 #include <asm/tlb.h>
 #include <asm/alternative.h>
 
+#define ARM64_ZONE_DMA_BITS	30
+
 /*
  * We need to be able to catch inadvertent references to memstart_addr
  * that occur (potentially in generic code) before arm64_memblock_init()
@@ -440,8 +443,10 @@  void __init arm64_memblock_init(void)
 
 	early_init_fdt_scan_reserved_mem();
 
-	if (IS_ENABLED(CONFIG_ZONE_DMA))
-		arm64_dma_phys_limit = max_zone_phys(ARCH_ZONE_DMA_BITS);
+	if (IS_ENABLED(CONFIG_ZONE_DMA)) {
+		zone_dma_bits = ARM64_ZONE_DMA_BITS;
+		arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS);
+	}
 
 	if (IS_ENABLED(CONFIG_ZONE_DMA32))
 		arm64_dma32_phys_limit = max_zone_phys(32);
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index c8bb14ff4713..f6c562acc3f8 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -329,13 +329,4 @@  struct vm_area_struct;
 #endif /* __ASSEMBLY__ */
 #include <asm/slice.h>
 
-/*
- * Allow 30-bit DMA for very limited Broadcom wifi chips on many powerbooks.
- */
-#ifdef CONFIG_PPC32
-#define ARCH_ZONE_DMA_BITS 30
-#else
-#define ARCH_ZONE_DMA_BITS 31
-#endif
-
 #endif /* _ASM_POWERPC_PAGE_H */
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 97e5922cb52e..8bab4e8b6bae 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -31,6 +31,7 @@ 
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/memremap.h>
+#include <linux/dma-direct.h>
 
 #include <asm/pgalloc.h>
 #include <asm/prom.h>
@@ -200,10 +201,10 @@  static int __init mark_nonram_nosave(void)
  * everything else. GFP_DMA32 page allocations automatically fall back to
  * ZONE_DMA.
  *
- * By using 31-bit unconditionally, we can exploit ARCH_ZONE_DMA_BITS to
- * inform the generic DMA mapping code.  32-bit only devices (if not handled
- * by an IOMMU anyway) will take a first dip into ZONE_NORMAL and get
- * otherwise served by ZONE_DMA.
+ * By using 31-bit unconditionally, we can exploit zone_dma_bits to inform the
+ * generic DMA mapping code.  32-bit only devices (if not handled by an IOMMU
+ * anyway) will take a first dip into ZONE_NORMAL and get otherwise served by
+ * ZONE_DMA.
  */
 static unsigned long max_zone_pfns[MAX_NR_ZONES];
 
@@ -236,9 +237,18 @@  void __init paging_init(void)
 	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
 	       (long int)((top_of_ram - total_ram) >> 20));
 
+	/*
+	 * Allow 30-bit DMA for very limited Broadcom wifi chips on many
+	 * powerbooks.
+	 */
+	if (IS_ENABLED(CONFIG_PPC32))
+		zone_dma_bits = 30;
+	else
+		zone_dma_bits = 31;
+
 #ifdef CONFIG_ZONE_DMA
 	max_zone_pfns[ZONE_DMA]	= min(max_low_pfn,
-				      1UL << (ARCH_ZONE_DMA_BITS - PAGE_SHIFT));
+				      1UL << (zone_dma_bits - PAGE_SHIFT));
 #endif
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 #ifdef CONFIG_HIGHMEM
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index 823578c6b9e2..a4d38092530a 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -177,8 +177,6 @@  static inline int devmem_is_allowed(unsigned long pfn)
 #define VM_DATA_DEFAULT_FLAGS	(VM_READ | VM_WRITE | \
 				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
 
-#define ARCH_ZONE_DMA_BITS	31
-
 #include <asm-generic/memory_model.h>
 #include <asm-generic/getorder.h>
 
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index c1d96e588152..ac44bd76db4b 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -118,6 +118,7 @@  void __init paging_init(void)
 
 	sparse_memory_present_with_active_regions(MAX_NUMNODES);
 	sparse_init();
+	zone_dma_bits = 31;
 	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
 	max_zone_pfns[ZONE_DMA] = PFN_DOWN(MAX_DMA_ADDRESS);
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index adf993a3bd58..d03af3605460 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -5,6 +5,8 @@ 
 #include <linux/dma-mapping.h>
 #include <linux/mem_encrypt.h>
 
+extern unsigned int zone_dma_bits;
+
 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
 #include <asm/dma-direct.h>
 #else
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 8402b29c280f..0b67c04e531b 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -16,12 +16,11 @@ 
 #include <linux/swiotlb.h>
 
 /*
- * Most architectures use ZONE_DMA for the first 16 Megabytes, but
- * some use it for entirely different regions:
+ * Most architectures use ZONE_DMA for the first 16 Megabytes, but some use it
+ * it for entirely different regions. In that case the arch code needs to
+ * override the variable below for dma-direct to work properly.
  */
-#ifndef ARCH_ZONE_DMA_BITS
-#define ARCH_ZONE_DMA_BITS 24
-#endif
+unsigned int zone_dma_bits __ro_after_init = 24;
 
 static void report_addr(struct device *dev, dma_addr_t dma_addr, size_t size)
 {
@@ -69,7 +68,7 @@  static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
 	 * Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
 	 * zones.
 	 */
-	if (*phys_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
+	if (*phys_mask <= DMA_BIT_MASK(zone_dma_bits))
 		return GFP_DMA;
 	if (*phys_mask <= DMA_BIT_MASK(32))
 		return GFP_DMA32;
@@ -395,7 +394,7 @@  int dma_direct_supported(struct device *dev, u64 mask)
 	u64 min_mask;
 
 	if (IS_ENABLED(CONFIG_ZONE_DMA))
-		min_mask = DMA_BIT_MASK(ARCH_ZONE_DMA_BITS);
+		min_mask = DMA_BIT_MASK(zone_dma_bits);
 	else
 		min_mask = DMA_BIT_MASK(32);