[PATCH][next] spi: dw: remove redundant assignment to variable len

[PATCH][next] spi: dw: remove redundant assignment to variable len

[Colin Ian King]

The variable id len being initialized with a value that is never read,
it is being re-assigned later on in a for-loop. The initialization is
redundant and can be removed.

Cleans up clang scan build warning:
drivers/spi/spi-dw-dma.c:580:17: warning: Although the value stored
to 'len' is used in the enclosing expression, the value is never
actually read from 'len' [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
---
 drivers/spi/spi-dw-dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index 0ecbb6c36e23..f4c209e5f52b 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -577,7 +577,7 @@ static int dw_spi_dma_transfer_one(struct dw_spi *dws,
 	sg_init_table(&tx_tmp, 1);
 	sg_init_table(&rx_tmp, 1);
 
-	for (base = 0, len = 0; base < xfer->len; base += len) {
+	for (base = 0; base < xfer->len; base += len) {
 		/* Fetch next Tx DMA data chunk */
 		if (!tx_len) {
 			tx_sg = !tx_sg ? &xfer->tx_sg.sgl[0] : sg_next(tx_sg);
-- 
2.39.2

Re: [PATCH][next] spi: dw: remove redundant assignment to variable len

[Colin King (gmail)]

On 15/02/2024 13:16, Colin Ian King wrote:
> The variable id len being initialized with a value that is never read,

should be "len is being.."

> it is being re-assigned later on in a for-loop. The initialization is
> redundant and can be removed.
> 
> Cleans up clang scan build warning:
> drivers/spi/spi-dw-dma.c:580:17: warning: Although the value stored
> to 'len' is used in the enclosing expression, the value is never
> actually read from 'len' [deadcode.DeadStores]
> 
> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
> ---
>   drivers/spi/spi-dw-dma.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
> index 0ecbb6c36e23..f4c209e5f52b 100644
> --- a/drivers/spi/spi-dw-dma.c
> +++ b/drivers/spi/spi-dw-dma.c
> @@ -577,7 +577,7 @@ static int dw_spi_dma_transfer_one(struct dw_spi *dws,
>   	sg_init_table(&tx_tmp, 1);
>   	sg_init_table(&rx_tmp, 1);
>   
> -	for (base = 0, len = 0; base < xfer->len; base += len) {
> +	for (base = 0; base < xfer->len; base += len) {
>   		/* Fetch next Tx DMA data chunk */
>   		if (!tx_len) {
>   			tx_sg = !tx_sg ? &xfer->tx_sg.sgl[0] : sg_next(tx_sg);

Re: [PATCH][next] spi: dw: remove redundant assignment to variable len

[Serge Semin]

On Thu, Feb 15, 2024 at 01:16:03PM +0000, Colin Ian King wrote:
> The variable id len being initialized with a value that is never read,
> it is being re-assigned later on in a for-loop. The initialization is
> redundant and can be removed.
> 
> Cleans up clang scan build warning:
> drivers/spi/spi-dw-dma.c:580:17: warning: Although the value stored
> to 'len' is used in the enclosing expression, the value is never
> actually read from 'len' [deadcode.DeadStores]

Don't know for sure now what was my original intention of having it
pre-initialized in the for-loop init section. Possibly what you
suggest to drop was a leftover from some another version of the
function implementation where the re-initialization was required. On
the other hand rather weak but still a justification of having that
assignment can be a maintainability so all the basic loop variables
would be safely pre-initialized before the code block is executed. But
in that case a more correct value would have been "xfer->len" instead
of zero. Anyway let's keep the code simple and drop the assignment.
Thanks for the patch.

Acked-by: Serge Semin <fancer.lancer@gmail.com>

-Serge(y)

> 
> Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
> ---
>  drivers/spi/spi-dw-dma.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
> index 0ecbb6c36e23..f4c209e5f52b 100644
> --- a/drivers/spi/spi-dw-dma.c
> +++ b/drivers/spi/spi-dw-dma.c
> @@ -577,7 +577,7 @@ static int dw_spi_dma_transfer_one(struct dw_spi *dws,
>  	sg_init_table(&tx_tmp, 1);
>  	sg_init_table(&rx_tmp, 1);
>  
> -	for (base = 0, len = 0; base < xfer->len; base += len) {
> +	for (base = 0; base < xfer->len; base += len) {
>  		/* Fetch next Tx DMA data chunk */
>  		if (!tx_len) {
>  			tx_sg = !tx_sg ? &xfer->tx_sg.sgl[0] : sg_next(tx_sg);
> -- 
> 2.39.2
> 

Re: [PATCH][next] spi: dw: remove redundant assignment to variable len

[Mark Brown]

On Thu, 15 Feb 2024 13:16:03 +0000, Colin Ian King wrote:
> The variable id len being initialized with a value that is never read,
> it is being re-assigned later on in a for-loop. The initialization is
> redundant and can be removed.
> 
> Cleans up clang scan build warning:
> drivers/spi/spi-dw-dma.c:580:17: warning: Although the value stored
> to 'len' is used in the enclosing expression, the value is never
> actually read from 'len' [deadcode.DeadStores]
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: dw: remove redundant assignment to variable len
      commit: 125b28b18926e050e770160a5897b81082304f8c

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark