On Mon, Sep 21, 2009 at 02:33, Li Yi wrote: > On Fri, 2009-09-18 at 14:29 -0700, Andrew Morton wrote: >> On Thu, 17 Sep 2009 18:03:16 -0400 >> Mike Frysinger <[email protected]> wrote: >> >> > From: Yi Li <[email protected]> >> > >> > For some MMC cards over SPI bus, it needs to lock the SPI bus for its own >> > use. The SPI transfer must not be interrupted by other SPI devices that >> > share the SPI bus with SPI MMC card. >> > >> > This patch introduces 2 APIs for SPI bus locking operation. >> > >> > Signed-off-by: Yi Li <[email protected]> >> > Signed-off-by: Bryan Wu <[email protected]> >> > Signed-off-by: Mike Frysinger <[email protected]> >> > --- >> > Andrew: we've posted these in the past with no response. could you pick >> > them up please ? >> > >> > drivers/spi/spi.c | 48 >> > +++++++++++++++++++++++++++++++++++++++++++++++ >> > include/linux/spi/spi.h | 7 ++++++ >> > 2 files changed, 55 insertions(+), 0 deletions(-) >> > >> > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c >> > index 70845cc..b82b8ad 100644 >> > --- a/drivers/spi/spi.c >> > +++ b/drivers/spi/spi.c >> > @@ -653,6 +653,54 @@ static void spi_complete(void *arg) >> > } >> > >> > /** >> > + * spi_lock_bus - lock SPI bus for exclusive access >> > + * @spi: device which want to lock the bus >> > + * Context: any >> > + * >> > + * Once the caller owns exclusive access to the SPI bus, >> > + * only messages for this device will be transferred. >> > + * Messages for other devices are queued but not transferred until >> > + * the bus owner unlock the bus. >> > + * >> > + * The caller may call spi_lock_bus() before spi_sync() or spi_async(). >> > + * So this call may be used in irq and other contexts which can't sleep, >> > + * as well as from task contexts which can sleep. >> >> Hence spi_lock_bus() basically has to use a spinning lock? >> >> So code which has called spi_lock_bus() cannot sleep until it calls >> spi_unlock_bus()? >> >> That's worth mentioning in the description. >> > Code called spi_lock_bus() _can_ sleep. This is mentioned in the > comments.
should add might_sleep() to the common spi_lock_bus() function then. -mike ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
