[v2,3/5] dma-direct: Turn zone_dma_bits default value into a define

Commit Message

Nicolas Saenz Julienne Oct. 10, 2020, 3:12 p.m. UTC

So as for architecture code to set their own default values when
relevant.

Signed-off-by: Nicolas Saenz Julienne <[e-mail]>
---

Note: This is not really needed, but I think it nicer having
architectures use this than setting zone_dma_bits in a random place in
arch code. That said, I'll hapily edit it out if you don't agree.

 include/linux/dma-direct.h | 3 +++
 kernel/dma/direct.c        | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

Patch

diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 18aade195884..e433d90cbacf 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -12,6 +12,9 @@ 
 #include <linux/mem_encrypt.h>
 #include <linux/swiotlb.h>
 
+#ifndef ZONE_DMA_BITS_DEFAULT
+#define ZONE_DMA_BITS_DEFAULT	24
+#endif
 extern unsigned int zone_dma_bits;
 
 /*
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 06c111544f61..c0d97f536e93 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -20,7 +20,7 @@ 
  * it for entirely different regions. In that case the arch code needs to
  * override the variable below for dma-direct to work properly.
  */
-unsigned int zone_dma_bits __ro_after_init = 24;
+unsigned int zone_dma_bits __ro_after_init = ZONE_DMA_BITS_DEFAULT;
 
 static inline dma_addr_t phys_to_dma_direct(struct device *dev,
 		phys_addr_t phys)