When compiled on i386, it produces several warnings:
./arch/x86/include/asm/bitops.h:457:22: warning: asm output is not an lvalue
./arch/x86/include/asm/bitops.h:457:22: warning: asm output is not an lvalue
./arch/x86/include/asm/bitops.h:457:22: warning: asm output is not an lvalue
./arch/x86/include/asm/bitops.h:457:22: warning: asm output is not an lvalue
./arch/x86/include/asm/bitops.h:457:22: warning: asm output is not an lvalue
./arch/x86/include/asm/bitops.h:457:22: warning: asm output is not an lvalue
I suspect that some gcc optimization could be causing the asm code to be
incorrectly generated. Splitting it into two macro calls fix the issues
and gets us rid of 6 smatch warnings, with is a good thing. As it should
not cause any troubles, as we're basically doing the same thing, let's
apply such change to vpe.c.
Cc: Benoit Parrot <bparrot@xxxxxx>
Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
---
drivers/media/platform/ti-vpe/vpe.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/media/platform/ti-vpe/vpe.c b/drivers/media/platform/ti-vpe/vpe.c
index 0626593a8b22..f0156b7759e9 100644
--- a/drivers/media/platform/ti-vpe/vpe.c
+++ b/drivers/media/platform/ti-vpe/vpe.c
@@ -1615,20 +1615,32 @@ static int __vpe_try_fmt(struct vpe_ctx *ctx, struct v4l2_format *f,
*/
depth_bytes = depth >> 3;
- if (depth_bytes == 3)
+ if (depth_bytes == 3) {
/*
* if bpp is 3(as in some RGB formats), the pixel width doesn't
* really help in ensuring line stride is 16 byte aligned
*/
w_align = 4;
- else
+ } else {
/*
* for the remainder bpp(4, 2 and 1), the pixel width alignment
* can ensure a line stride alignment of 16 bytes. For example,
* if bpp is 2, then the line stride can be 16 byte aligned if
* the width is 8 byte aligned
*/
- w_align = order_base_2(VPDMA_DESC_ALIGN / depth_bytes);
+
+ /*
+ * HACK: using order_base_2() here causes lots of asm output
+ * errors with smatch, on i386:
+ * ./arch/x86/include/asm/bitops.h:457:22:
+ * warning: asm output is not an lvalue
+ * Perhaps some gcc optimization is doing the wrong thing
+ * there.
+ * Let's get rid of them by doing the calculus on two steps
+ */
+ w_align = roundup_pow_of_two(VPDMA_DESC_ALIGN / depth_bytes);
+ w_align = ilog2(w_align);
+ }
v4l_bound_align_image(&pix->width, MIN_W, MAX_W, w_align,
&pix->height, MIN_H, MAX_H, H_ALIGN,
--
2.9.3
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