| Message ID | 39ffc897bd2e5fd48a3141ed4cd122a80c5bbb20.1390544495.git.baruch@tkos.co.il (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Fri, Jan 24, 2014 at 7:28 AM, Baruch Siach <baruch@tkos.co.il> wrote: > --- a/include/linux/spi/spi.h > +++ b/include/linux/spi/spi.h > @@ -285,7 +285,9 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) > * @transfer_one: transfer a single spi_transfer. When the > * driver is finished with this transfer it must call > * spi_finalize_current_transfer() so the subsystem can issue > - * the next transfer > + * the next transfer. Note: transfer_one and > + * transfer_one_message are mutually exclusive; when both are > + * set, transfer_one takes precedence. I find this a bit difficult to grasp. What does "take precedence" mean in this context? The default spi_transfer_one_message() uses .transfer_one(). But if .transfer_one_message() is set, it depends on your own driver if .transfer_one() is used or not. 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
Hi Gerrt, On Fri, Jan 24, 2014 at 08:44:32AM +0100, Geert Uytterhoeven wrote: > On Fri, Jan 24, 2014 at 7:28 AM, Baruch Siach <baruch@tkos.co.il> wrote: > > --- a/include/linux/spi/spi.h > > +++ b/include/linux/spi/spi.h > > @@ -285,7 +285,9 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) > > * @transfer_one: transfer a single spi_transfer. When the > > * driver is finished with this transfer it must call > > * spi_finalize_current_transfer() so the subsystem can issue > > - * the next transfer > > + * the next transfer. Note: transfer_one and > > + * transfer_one_message are mutually exclusive; when both are > > + * set, transfer_one takes precedence. > > I find this a bit difficult to grasp. What does "take precedence" mean in > this context? > > The default spi_transfer_one_message() uses .transfer_one(). > But if .transfer_one_message() is set, it depends on your own driver if > .transfer_one() is used or not. Of course. I misread the code. How about this: Note: transfer_one and transfer_one_message are mutually exclusive; when both are set, the transfer_one callback is not called by the generic subsystem. Thanks again, baruch
On Fri, Jan 24, 2014 at 9:12 AM, Baruch Siach <baruch@tkos.co.il> wrote: >> > @@ -285,7 +285,9 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) >> > * @transfer_one: transfer a single spi_transfer. When the >> > * driver is finished with this transfer it must call >> > * spi_finalize_current_transfer() so the subsystem can issue >> > - * the next transfer >> > + * the next transfer. Note: transfer_one and >> > + * transfer_one_message are mutually exclusive; when both are >> > + * set, transfer_one takes precedence. >> >> I find this a bit difficult to grasp. What does "take precedence" mean in >> this context? >> >> The default spi_transfer_one_message() uses .transfer_one(). >> But if .transfer_one_message() is set, it depends on your own driver if >> .transfer_one() is used or not. > > Of course. I misread the code. How about this: > > Note: transfer_one and transfer_one_message are mutually exclusive; when both > are set, the transfer_one callback is not called by the generic subsystem. Sounds fine to me, thanks! 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
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 8c62ba74dd91..060b21e82e73 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -285,7 +285,9 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) * @transfer_one: transfer a single spi_transfer. When the * driver is finished with this transfer it must call * spi_finalize_current_transfer() so the subsystem can issue - * the next transfer + * the next transfer. Note: transfer_one and + * transfer_one_message are mutually exclusive; when both are + * set, transfer_one takes precedence. * @unprepare_message: undo any work done by prepare_message(). * @cs_gpios: Array of GPIOs to use as chip select lines; one per CS * number. Any individual value may be -ENOENT for CS lines that
Explicitly note the transfer_one and transfer_one_message are mutually exclusive, to make the text a little more newcomers friendly. Signed-off-by: Baruch Siach <baruch@tkos.co.il> --- include/linux/spi/spi.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)