Re: [Nios2-dev] [PATCH] spi: bitbang: Make setup_transfer callback optional

From: Ezequiel Garcia
Date: Mon Apr 13 2015 - 20:25:50 EST


Hi Pelle,

Just some minor nitpicks.

On 04/13/2015 07:08 AM, Pelle Nilsson wrote:
> spi-altera doesn't register this callback, and doesn't have a need for it,
> but currently causes a NULL dereference when callback is called.

This commit needs a Signed-off-by tag.

Also, maybe you can avoid talking about spi-altera in the commit, since
this change is not related to it. Instead you can explain that some SPI
controllers don't register the callback (e.g. spi-altera) and so this
commit makes it optional to prevent a NULL dereference.

You explained in the cover that you are fixing commit 30af9b558a56 so
you probably want to add a Fixes tag (Documentation/SubmittingPatches
explains this procedure). The stable team will use the Fixes tag to
backport the change if needed.

> ---
> drivers/spi/spi-bitbang.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
> index 5ef6638..d02057d 100644
> --- a/drivers/spi/spi-bitbang.c
> +++ b/drivers/spi/spi-bitbang.c
> @@ -180,7 +180,7 @@ int spi_bitbang_setup(struct spi_device *spi)
> {
> struct spi_bitbang_cs *cs = spi->controller_state;
> struct spi_bitbang *bitbang;
> - int retval;
> + int retval = 0;
> unsigned long flags;
>
> bitbang = spi_master_get_devdata(spi->master);
> @@ -197,7 +197,8 @@ int spi_bitbang_setup(struct spi_device *spi)
> if (!cs->txrx_word)
> return -EINVAL;
>
> - retval = bitbang->setup_transfer(spi, NULL);
> + if (bitbang->setup_transfer)

retval is only used in this scope, so you can declare it only here:

if (bitbang->setup_transfer) {
int retval = bitbang->setup_transfer(spi, NULL);
if (retval < 0)
return retval;
}

> + retval = bitbang->setup_transfer(spi, NULL);
> if (retval < 0)
> return retval;
>
> @@ -295,9 +296,11 @@ static int spi_bitbang_transfer_one(struct spi_master *master,
>
> /* init (-1) or override (1) transfer params */
> if (do_setup != 0) {
> - status = bitbang->setup_transfer(spi, t);
> - if (status < 0)
> - break;
> + if (bitbang->setup_transfer) {
> + status = bitbang->setup_transfer(spi, t);
> + if (status < 0)
> + break;
> + }
> if (do_setup == -1)
> do_setup = 0;
> }
>

Other than that, the commit looks good.
--
Ezequiel Garcia, VanguardiaSur
www.vanguardiasur.com.ar
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