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| author | Arnd Bergmann <arnd@arndb.de> | 2021-11-03 18:33:12 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-18 21:17:11 +0300 |
| commit | 0bf8323e2c74012d38a61d4f9470fe7f33376bd4 (patch) | |
| tree | b775efcb08aa5b78638994fa45f668303080f8ff /drivers/dma | |
| parent | 4ee1ac7f3cf56b2e9f629208bdf28d81397a48dd (diff) | |
| download | linux-0bf8323e2c74012d38a61d4f9470fe7f33376bd4.tar.xz | |
dmaengine: stm32-dma: avoid 64-bit division in stm32_dma_get_max_width
[ 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>
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/stm32-dma.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c index c276a39aa793..7dfc743ac433 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; @@ -756,7 +756,7 @@ 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; @@ -812,7 +812,7 @@ 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; |