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[1/2] dmaengine: xilinx: xdma: Fix operator precedence in xdma_prep_interleaved_dma()

Message ID 20231222-dma-xilinx-xdma-clang-fixes-v1-1-84a18ff184d2@kernel.org (mailing list archive)
State New, archived
Headers show
Series dmaengine: xilinx: xdma: Fix two clang warnings | expand

Commit Message

Nathan Chancellor Dec. 22, 2023, 6:06 p.m. UTC 
Clang warns (or errors with CONFIG_WERROR=y):

  drivers/dma/xilinx/xdma.c:757:68: error: operator '?:' has lower precedence than '+'; '+' will be evaluated first [-Werror,-Wparentheses]
    757 |                 src_addr += dmaengine_get_src_icg(xt, &xt->sgl[i]) + xt->src_inc ?
        |                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^
  drivers/dma/xilinx/xdma.c:757:68: note: place parentheses around the '+' expression to silence this warning
    757 |                 src_addr += dmaengine_get_src_icg(xt, &xt->sgl[i]) + xt->src_inc ?
        |                                                                                  ^
        |                             (                                                   )
  drivers/dma/xilinx/xdma.c:757:68: note: place parentheses around the '?:' expression to evaluate it first
    757 |                 src_addr += dmaengine_get_src_icg(xt, &xt->sgl[i]) + xt->src_inc ?
        |                                                                                  ^
        |                                                                      (
    758 |                                                               xt->sgl[i].size : 0;
        |
        |                                                                                  )
  drivers/dma/xilinx/xdma.c:759:68: error: operator '?:' has lower precedence than '+'; '+' will be evaluated first [-Werror,-Wparentheses]
    759 |                 dst_addr += dmaengine_get_dst_icg(xt, &xt->sgl[i]) + xt->dst_inc ?
        |                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^
  drivers/dma/xilinx/xdma.c:759:68: note: place parentheses around the '+' expression to silence this warning
    759 |                 dst_addr += dmaengine_get_dst_icg(xt, &xt->sgl[i]) + xt->dst_inc ?
        |                                                                                  ^
        |                             (                                                   )
  drivers/dma/xilinx/xdma.c:759:68: note: place parentheses around the '?:' expression to evaluate it first
    759 |                 dst_addr += dmaengine_get_dst_icg(xt, &xt->sgl[i]) + xt->dst_inc ?
        |                                                                                  ^
        |                                                                      (
    760 |                                                               xt->sgl[i].size : 0;
        |
        |                                                                                  )

The src_inc and dst_inc members of 'struct dma_interleaved_template' are
booleans, so it does not make sense for the addition to happen first.
Wrap the conditional operator in parantheses so it is evaluated first.

Closes: https://github.com/ClangBuiltLinux/linux/issues/1971
Fixes: 2f8f90cd2f8d ("dmaengine: xilinx: xdma: Implement interleaved DMA transfers")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 drivers/dma/xilinx/xdma.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
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Patch

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 4ebc90b41bdb..d5b9fc3fd955 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -754,10 +754,10 @@  xdma_prep_interleaved_dma(struct dma_chan *chan,
 	dst_addr = xt->dst_start;
 	for (i = 0; i < xt->frame_size; ++i) {
 		desc_num += xdma_fill_descs(sw_desc, src_addr, dst_addr, xt->sgl[i].size, desc_num);
-		src_addr += dmaengine_get_src_icg(xt, &xt->sgl[i]) + xt->src_inc ?
-							      xt->sgl[i].size : 0;
-		dst_addr += dmaengine_get_dst_icg(xt, &xt->sgl[i]) + xt->dst_inc ?
-							      xt->sgl[i].size : 0;
+		src_addr += dmaengine_get_src_icg(xt, &xt->sgl[i]) + (xt->src_inc ?
+							      xt->sgl[i].size : 0);
+		dst_addr += dmaengine_get_dst_icg(xt, &xt->sgl[i]) + (xt->dst_inc ?
+							      xt->sgl[i].size : 0);
 		period_size += xt->sgl[i].size;
 	}
 	sw_desc->period_size = period_size;