| Message ID | 20190924110547.14770-2-lukma@denx.de (mailing list archive) |
|---|---|
| State | Superseded |
| Commit | bf390d25e03b38248a0a4f7d0002bbb495a82fe9 |
| Headers | show |
| Series | spi: Fix problem with interrupted slave transmission | expand |
Hi Lukasz, On Thu, Sep 26, 2019 at 3:33 AM Lukasz Majewski <lukma@denx.de> wrote: > This change is necessary for spidev devices (e.g. /dev/spidev3.0) working > in the slave mode (like NXP's dspi driver for Vybrid SoC). > > When SPI HW works in this mode - the master is responsible for providing > CS and CLK signals. However, when some fault happens - like for example > distortion on SPI lines - the SPI Linux driver needs a chance to recover > from this abnormal situation and prepare itself for next (correct) > transmission. > > This change doesn't pose any threat on drivers working in master mode as > spi_slave_abort() function checks if SPI slave mode is supported. > > Signed-off-by: Lukasz Majewski <lukma@denx.de> Thanks for your patch! Yesterday I saw this appear on spi/for-next, but I couldn't find the email in my mbox. Today it has arrived. Looks like gmail had some troubles ("Delivered after 138401 seconds", ugh). > --- a/drivers/spi/spidev.c > +++ b/drivers/spi/spidev.c > @@ -627,6 +627,7 @@ static int spidev_release(struct inode *inode, struct file *filp) > if (dofree) > kfree(spidev); > } > + spi_slave_abort(spidev->spi); Looks good to me. Just wondering if this should be done for the last user only, i.e. in the "if" block above, like resetting speed_hz? > mutex_unlock(&device_list_lock); > > return 0; Gr{oetje,eeting}s, Geert
Hi Geert, > Hi Lukasz, > > On Thu, Sep 26, 2019 at 3:33 AM Lukasz Majewski <lukma@denx.de> wrote: > > This change is necessary for spidev devices (e.g. /dev/spidev3.0) > > working in the slave mode (like NXP's dspi driver for Vybrid SoC). > > > > When SPI HW works in this mode - the master is responsible for > > providing CS and CLK signals. However, when some fault happens - > > like for example distortion on SPI lines - the SPI Linux driver > > needs a chance to recover from this abnormal situation and prepare > > itself for next (correct) transmission. > > > > This change doesn't pose any threat on drivers working in master > > mode as spi_slave_abort() function checks if SPI slave mode is > > supported. > > > > Signed-off-by: Lukasz Majewski <lukma@denx.de> > > Thanks for your patch! > > Yesterday I saw this appear on spi/for-next, but I couldn't find the > email in my mbox. Today it has arrived. Looks like gmail had some > troubles ("Delivered after 138401 seconds", ugh). I've already sent v2 of this patch, as Intel Linux test setup spot the error with lack of #define guards. > > > --- a/drivers/spi/spidev.c > > +++ b/drivers/spi/spidev.c > > @@ -627,6 +627,7 @@ static int spidev_release(struct inode *inode, > > struct file *filp) if (dofree) > > kfree(spidev); > > } > > + spi_slave_abort(spidev->spi); > > Looks good to me. Just wondering if this should be done for the last > user only, i.e. in the "if" block above, like resetting speed_hz? I also thought about this. However, from my use case the user must end the transmission with CTRL+C on his user space program, which in turn communicate via SPI with /dev/spidev3.0. There might be many (potential) programs using the /dev/spidev3.0 at the same time, so the usage count may be not one. For the above reason I've moved it outside the above if(). > > > mutex_unlock(&device_list_lock); > > > > return 0; > > Gr{oetje,eeting}s, > > Geert > Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index 255786f2e844..fe9ea7e55e5b 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -627,6 +627,7 @@ static int spidev_release(struct inode *inode, struct file *filp) if (dofree) kfree(spidev); } + spi_slave_abort(spidev->spi); mutex_unlock(&device_list_lock); return 0;
This change is necessary for spidev devices (e.g. /dev/spidev3.0) working in the slave mode (like NXP's dspi driver for Vybrid SoC). When SPI HW works in this mode - the master is responsible for providing CS and CLK signals. However, when some fault happens - like for example distortion on SPI lines - the SPI Linux driver needs a chance to recover from this abnormal situation and prepare itself for next (correct) transmission. This change doesn't pose any threat on drivers working in master mode as spi_slave_abort() function checks if SPI slave mode is supported. Signed-off-by: Lukasz Majewski <lukma@denx.de> --- drivers/spi/spidev.c | 1 + 1 file changed, 1 insertion(+)