| Message ID | 1395201227.16346.1.camel@phoenix (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Mar 19, 2014 at 4:53 AM, Axel Lin <axel.lin@ingics.com> wrote: > Reject transfer if both tx_buf and rx_buf are NULL for non-zero length transfer. > Add the checking in spi core so we can remove the same checking in various > drivers. Just wondering: are there any SPI slave drivers that implement dummy cycles this way? > Signed-off-by: Axel Lin <axel.lin@ingics.com> > --- > drivers/spi/spi.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 26b331d..0a29d2a 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -1876,6 +1876,10 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) > if (xfer->len % w_size) > return -EINVAL; > > + /* non-zero length transfer must has tx_buf or rx_buf */ have > + if (xfer->len && !xfer->tx_buf && !xfer->rx_buf) > + return -EINVAL; > + Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
2014-03-19 16:06 GMT+08:00 Geert Uytterhoeven <geert@linux-m68k.org>: > On Wed, Mar 19, 2014 at 4:53 AM, Axel Lin <axel.lin@ingics.com> wrote: >> Reject transfer if both tx_buf and rx_buf are NULL for non-zero length transfer. >> Add the checking in spi core so we can remove the same checking in various >> drivers. > > Just wondering: are there any SPI slave drivers that implement dummy cycles > this way? I think I found one such case: drivers/net/wireless/libertas/if_spi.c the dummy_trans has non-zero length, and both tx_buf and rx_buf are NULL. But that means it doesn't work with master drivers with this checking, e.g. all drivers using bitbang library has this checking. Regards, Axel -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Mar 19, 2014 at 11:43:55PM +0800, Axel Lin wrote: > 2014-03-19 16:06 GMT+08:00 Geert Uytterhoeven <geert@linux-m68k.org>: > > Just wondering: are there any SPI slave drivers that implement dummy cycles > > this way? > I think I found one such case: > drivers/net/wireless/libertas/if_spi.c > the dummy_trans has non-zero length, and both tx_buf and rx_buf are NULL. > But that means it doesn't work with master drivers with this checking, e.g. > all drivers using bitbang library has this checking. I have to say that this seems rather abusive on the part of the driver, it's going to cause implementation issues in the masters - I expect more than just those that check aren't doing to do the right thing.
On Wed, Mar 19, 2014 at 09:06:31AM +0100, Geert Uytterhoeven wrote: > On Wed, Mar 19, 2014 at 4:53 AM, Axel Lin <axel.lin@ingics.com> wrote: > > Reject transfer if both tx_buf and rx_buf are NULL for non-zero length transfer. > > Add the checking in spi core so we can remove the same checking in various > > drivers. > Just wondering: are there any SPI slave drivers that implement dummy cycles > this way? The ChromeOS EC apparently does this.
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 26b331d..0a29d2a 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1876,6 +1876,10 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) if (xfer->len % w_size) return -EINVAL; + /* non-zero length transfer must has tx_buf or rx_buf */ + if (xfer->len && !xfer->tx_buf && !xfer->rx_buf) + return -EINVAL; + if (xfer->speed_hz && master->min_speed_hz && xfer->speed_hz < master->min_speed_hz) return -EINVAL;
Reject transfer if both tx_buf and rx_buf are NULL for non-zero length transfer. Add the checking in spi core so we can remove the same checking in various drivers. Signed-off-by: Axel Lin <axel.lin@ingics.com> --- drivers/spi/spi.c | 4 ++++ 1 file changed, 4 insertions(+)