Re: [PATCH V2] spi: remove check for bits_per_word on transfer fromlow level driver

[Laxman Dewangan]

On Wednesday 19 December 2012 09:54 PM, Grant Likely wrote:
> On Tue, 18 Dec 2012 14:25:43 +0530, Laxman Dewangan<ldewangan@xxxxxxxxxx>  wrote:
> > The spi core make sure that each transfer structure have the proper
> > setting for bits_per_word before calling low level transfer APIs.
> >
> > Hence it is no more require to check again in low level driver for
> > this field whether this is set correct or not. Removing such code
> > from low level driver.
> >
> > Signed-off-by: Laxman Dewangan<ldewangan@xxxxxxxxxx>
> [...]
> > */
> >
> >   		if (prev_speed_hz != speed_hz
> > @@ -316,9 +315,8 @@ static int txx9spi_transfer(struct spi_device *spi, struct spi_message *m)
> >   	/* check each transfer's parameters */
> >   	list_for_each_entry (t,&m->transfers, transfer_list) {
> >   		u32 speed_hz = t->speed_hz ? : spi->max_speed_hz;
> > -		u8 bits_per_word = t->bits_per_word ? : spi->bits_per_word;
> > +		u8 bits_per_word = t->bits_per_word;
> >
> > -		bits_per_word = bits_per_word ? : 8;
> Have you verified here that bits_per_word can never be '0' here? What is
> the path that ensures spi->bits_per_word (and hence t->bits_per_word) is
> set to 8 here?
>
> Otherwise the patch looks good. Thanks for doing this work.


When we do the spi_add_device(), the spi_setup() get called.
In spi_setup, it make  sure that spi->bits_per_word is not zero.

in spi_setup(spi.c)

if (!spi->bits_per_word)
                spi->bits_per_word = 8;


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