X-Git-Url: https://git.kernelconcepts.de/?p=karo-tx-linux.git;a=blobdiff_plain;f=arch%2Farm%2FKconfig;h=0e16cca1d01168ad6fb78112879aa87835b5c0f4;hp=a955d89ed83642cd5b5b62d7954edd8241637730;hb=887cbce0adead8dc394157b8e53603ed001a3060;hpb=d414c104e26fd3b597f855cc29473a8b1527fb4c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a955d89ed836..0e16cca1d011 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -49,6 +49,7 @@ config ARM
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_UID16
+	select HAVE_VIRT_TO_BUS
 	select KTIME_SCALAR
 	select PERF_USE_VMALLOC
 	select RTC_LIB
@@ -77,6 +78,27 @@ config ARM_DMA_USE_IOMMU
 	select ARM_HAS_SG_CHAIN
 	select NEED_SG_DMA_LENGTH
 
+if ARM_DMA_USE_IOMMU
+
+config ARM_DMA_IOMMU_ALIGNMENT
+	int "Maximum PAGE_SIZE order of alignment for DMA IOMMU buffers"
+	range 4 9
+	default 8
+	help
+	  DMA mapping framework by default aligns all buffers to the smallest
+	  PAGE_SIZE order which is greater than or equal to the requested buffer
+	  size. This works well for buffers up to a few hundreds kilobytes, but
+	  for larger buffers it just a waste of address space. Drivers which has
+	  relatively small addressing window (like 64Mib) might run out of
+	  virtual space with just a few allocations.
+
+	  With this parameter you can specify the maximum PAGE_SIZE order for
+	  DMA IOMMU buffers. Larger buffers will be aligned only to this
+	  specified order. The order is expressed as a power of two multiplied
+	  by the PAGE_SIZE.
+
+endif
+
 config HAVE_PWM
 	bool