From: Arnd Bergmann arnd@arndb.de
[ Upstream commit 2498363310e9b5e5de0e104709adc35c9f3ff7d9 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/dma/stm32-dma.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index 1b2063fb3d1d6..bf3042b655485 100644 --- a/drivers/dma/stm32-dma.c +++ b/drivers/dma/stm32-dma.c @@ -278,7 +278,7 @@ 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; @@ -754,7 +754,7 @@ 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; @@ -810,7 +810,7 @@ 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;