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authorArnd Bergmann <arnd@arndb.de>2021-11-03 16:33:12 +0100
committerVinod Koul <vkoul@kernel.org>2021-11-09 11:20:35 +0530
commit2498363310e9b5e5de0e104709adc35c9f3ff7d9 (patch)
treee84ac41c5fb21ec3da618b6b467f05a3a823e935 /drivers/dma
parente0674853943287669a82d1ffe09a700944615978 (diff)
dmaengine: stm32-dma: avoid 64-bit division in stm32_dma_get_max_width
Using the % operator on a 64-bit variable is expensive and can cause a link failure: arm-linux-gnueabi-ld: drivers/dma/stm32-dma.o: in function `stm32_dma_get_max_width': stm32-dma.c:(.text+0x170): undefined reference to `__aeabi_uldivmod' arm-linux-gnueabi-ld: drivers/dma/stm32-dma.o: in function `stm32_dma_set_xfer_param': stm32-dma.c:(.text+0x1cd4): undefined reference to `__aeabi_uldivmod' As we know that we just want to check the alignment in stm32_dma_get_max_width(), there is no need for a full division, and using a simple mask is a faster replacement. Same in stm32_dma_set_xfer_param(), change this to only allow burst transfers if the address is a multiple of the length. stm32_dma_get_best_burst just after will take buf_len into account to fix burst in case of misalignment. Fixes: b20fd5fa310c ("dmaengine: stm32-dma: fix stm32_dma_get_max_width") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com> Link: https://lore.kernel.org/r/20211103153312.41483-1-amelie.delaunay@foss.st.com Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/stm32-dma.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 2283c500f4ce..83a37a6955a3 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -280,7 +280,7 @@ static enum dma_slave_buswidth stm32_dma_get_max_width(u32 buf_len,
max_width > DMA_SLAVE_BUSWIDTH_1_BYTE)
max_width = max_width >> 1;
- if (buf_addr % max_width)
+ if (buf_addr & (max_width - 1))
max_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
return max_width;
@@ -757,7 +757,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
* Set memory burst size - burst not possible if address is not aligned on
* the address boundary equal to the size of the transfer
*/
- if (buf_addr % buf_len)
+ if (buf_addr & (buf_len - 1))
src_maxburst = 1;
else
src_maxburst = STM32_DMA_MAX_BURST;
@@ -813,7 +813,7 @@ static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
* Set memory burst size - burst not possible if address is not aligned on
* the address boundary equal to the size of the transfer
*/
- if (buf_addr % buf_len)
+ if (buf_addr & (buf_len - 1))
dst_maxburst = 1;
else
dst_maxburst = STM32_DMA_MAX_BURST;