Re: [PATCH 09/11] spi-dw: Fix condition in spi_dw_{writer/reader}

[Dirk Brandewie]

On 06/22/2011 07:45 PM, Feng Tang wrote:
> On Thu, 23 Jun 2011 10:00:11 +0800
> "dirk.brandewie@xxxxxxxxx"<dirk.brandewie@xxxxxxxxx>  wrote:
>
> > From: Dirk Brandewie<dirk.brandewie@xxxxxxxxx>
> >
> > Fix the condition based on whether the current transfer has a tx/rx
> > buffer.
> >
> > Signed-off-by: Dirk Brandewie<dirk.brandewie@xxxxxxxxx>
> > ---
> >   drivers/spi/spi-dw.c |    6 +++---
> >   1 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
> > index cc38aa0..35b952b 100644
> > --- a/drivers/spi/spi-dw.c
> > +++ b/drivers/spi/spi-dw.c
> > @@ -193,8 +193,8 @@ static void spi_dw_writer(struct spi_dw *dws)
> >   	u16 txw = 0;
> >
> >   	while (max--) {
> > -		/* Set the tx word if the transfer's original "tx"
> > is not null */
> > -		if (dws->tx_end - dws->len) {
> > +		/* Set the tx word if the transfer's "tx" is not
> > null */
> > +		if (dws->tx) {
>
> No, in current mainstream code, the dws->tx is changing, see code:
> 	dws->tx += dws->n_bytes;
> so we have to use if (dws->tx_end - dws->len) for now, maybe
> we can use some bit to indicate whether the original tx is null

If dws->tx is non-null then it points to a valid buffer, it is unconditionally 
set with dws->tx = (void *)transfer->tx_buf when the transfer is setup.  if the 
original transfer->tx_buf is non-null then this change works.

> >   			if (dws->n_bytes == 1)
> >   				txw = *(u8 *)(dws->tx);
> >   			else
> > @@ -213,7 +213,7 @@ static void spi_dw_reader(struct spi_dw *dws)
> >   	while (max--) {
> >   		rxw = dw_readw(dws, dr);
> >   		/* Care rx only if the transfer's original "rx" is
> > not null */
> > -		if (dws->rx_end - dws->len) {
> > +		if (dws->rx) {
> >   			if (dws->n_bytes == 1)
> >   				*(u8 *)(dws->rx) = rxw;
> >   			else

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