cma: decrease CMA_ALIGNMENT lower limit to 2

On an embedded system with a tiny (1 MiB) CMA area for video memory, and
a simple enough video pipeline, we can decrease the CMA_ALIGNMENT by a
factor of 2 to avoid wasting memory, as all the allocations for video
buffers will be of the exact same size (dictated by the size of the
screen).

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index c5f7170..6479967 100644 (file)
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -177,7 +177,7 @@ endchoice
 
 config CMA_ALIGNMENT
        int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
-       range 4 12
+       range 2 12
        default 8
        help
          DMA mapping framework by default aligns all buffers to the smallest