linux-kernel - [PATCH -next] dmaengine: fsl-dpaa2-qdma: Remove unnecessary local variables in DPDMAI_CMD

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Date:   Tue, 22 Oct 2019 10:16:48 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Peng Ma <peng.ma@....com>, Vinod Koul <vkoul@...nel.org>
Cc:     Dan Williams <dan.j.williams@...el.com>, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        Nathan Chancellor <natechancellor@...il.com>
Subject: [PATCH -next] dmaengine: fsl-dpaa2-qdma: Remove unnecessary local variables in DPDMAI_CMD_CREATE macro

Clang warns:

drivers/dma/fsl-dpaa2-qdma/dpdmai.c:148:25: warning: variable 'cfg' is
uninitialized when used within its own initialization [-Wuninitialized]
        DPDMAI_CMD_CREATE(cmd, cfg);
        ~~~~~~~~~~~~~~~~~~~~~~~^~~~
drivers/dma/fsl-dpaa2-qdma/dpdmai.c:42:24: note: expanded from macro
'DPDMAI_CMD_CREATE'
        typeof(_cfg) (cfg) = (_cfg); \
                      ~~~     ^~~~
1 warning generated.

Looking at the preprocessed source, we can see that this is true.

int dpdmai_create(struct fsl_mc_io *mc_io, u32 cmd_flags,
                  const struct dpdmai_cfg *cfg, u16 *token)
{
        struct fsl_mc_command cmd = { 0 };
        int err;

        cmd.header = mc_encode_cmd_header((((0x90E) << 4) | 0), cmd_flags, 0);
        do {
                typeof(cmd)(cmd) = (cmd);
                typeof(cfg)(cfg) = (cfg);
                ((cmd).params[0] |= mc_enc((8), (8), (cfg)->priorities[0]));
                ((cmd).params[0] |= mc_enc((16), (8), (cfg)->priorities[1]));
        } while (0);

I cannot see a good reason to create another version of cfg when the
parameter one will work perfectly fine and cmd can just be used as is.
Remove them to fix this warning.

Fixes: f2835adf8afb ("dmaengine: fsl-dpaa2-qdma: Add the DPDMAI(Data Path DMA Interface) support")
Link: https://github.com/ClangBuiltLinux/linux/issues/746
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 drivers/dma/fsl-dpaa2-qdma/dpdmai.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/dma/fsl-dpaa2-qdma/dpdmai.c b/drivers/dma/fsl-dpaa2-qdma/dpdmai.c
index fbc2b2f39bec..f26c0b71688a 100644
--- a/drivers/dma/fsl-dpaa2-qdma/dpdmai.c
+++ b/drivers/dma/fsl-dpaa2-qdma/dpdmai.c
@@ -36,10 +36,8 @@ struct dpdmai_rsp_get_tx_queue {
 	((_cmd).params[_param] |= mc_enc((_offset), (_width), _arg))
 
 /* cmd, param, offset, width, type, arg_name */
-#define DPDMAI_CMD_CREATE(_cmd, _cfg) \
+#define DPDMAI_CMD_CREATE(cmd, cfg) \
 do { \
-	typeof(_cmd) (cmd) = (_cmd); \
-	typeof(_cfg) (cfg) = (_cfg); \
 	MC_CMD_OP(cmd, 0, 8,  8,  u8,  (cfg)->priorities[0]);\
 	MC_CMD_OP(cmd, 0, 16, 8,  u8,  (cfg)->priorities[1]);\
 } while (0)
-- 
2.23.0