From: Alexander Sverdlin <[email protected]>
Commit f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
has changed the user-space interface so that bogus SPI_CS_HIGH started
to appear in the mask returned by SPI_IOC_RD_MODE even for active-low CS
pins. Commit 138c9c32f090
("spi: spidev: Fix CS polarity if GPIO descriptors are used") fixed only
SPI_IOC_WR_MODE part of the problem. Let's fix SPI_IOC_RD_MODE
symmetrically.
Test case:
#include <sys/ioctl.h>
#include <fcntl.h>
#include <linux/spi/spidev.h>
int main(int argc, char **argv)
{
char modew = SPI_CPHA;
char moder;
int f = open("/dev/spidev0.0", O_RDWR);
if (f < 0)
return 1;
ioctl(f, SPI_IOC_WR_MODE, &modew);
ioctl(f, SPI_IOC_RD_MODE, &moder);
return moder == modew ? 0 : 2;
}
Fixes: f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
Signed-off-by: Alexander Sverdlin <[email protected]>
---
drivers/spi/spidev.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index b2775d82d2d7b..23177a7c916c3 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -377,8 +377,17 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
switch (cmd) {
/* read requests */
case SPI_IOC_RD_MODE:
- retval = put_user(spi->mode & SPI_MODE_MASK,
- (__u8 __user *)arg);
+ tmp = spi->mode;
+
+ {
+ struct spi_controller *ctlr = spi->controller;
+
+ if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
+ ctlr->cs_gpiods[spi->chip_select])
+ tmp &= ~SPI_CS_HIGH;
+ }
+
+ retval = put_user(tmp & SPI_MODE_MASK, (__u8 __user *)arg);
break;
case SPI_IOC_RD_MODE32:
retval = put_user(spi->mode & SPI_MODE_MASK,
--
2.34.1
On Wed, Nov 30, 2022 at 03:39:48PM +0100, A. Sverdlin wrote:
> /* read requests */
> case SPI_IOC_RD_MODE:
> - retval = put_user(spi->mode & SPI_MODE_MASK,
> - (__u8 __user *)arg);
> + tmp = spi->mode;
> +
> + {
> + struct spi_controller *ctlr = spi->controller;
> +
> + if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
> + ctlr->cs_gpiods[spi->chip_select])
> + tmp &= ~SPI_CS_HIGH;
> + }
> +
> + retval = put_user(tmp & SPI_MODE_MASK, (__u8 __user *)arg);
> break;
> case SPI_IOC_RD_MODE32:
> retval = put_user(spi->mode & SPI_MODE_MASK,
What about SPI_IOC_RD_MODE_32? On the write path the code is shared...
Hello Mark,
On Wed, 2022-11-30 at 14:57 +0000, Mark Brown wrote:
> > /* read requests */
> > case SPI_IOC_RD_MODE:
> > - retval = put_user(spi->mode & SPI_MODE_MASK,
> > - (__u8 __user *)arg);
> > + tmp = spi->mode;
> > +
> > + {
> > + struct spi_controller *ctlr = spi-
> > >controller;
> > +
> > + if (ctlr->use_gpio_descriptors && ctlr-
> > >cs_gpiods &&
> > + ctlr->cs_gpiods[spi->chip_select])
> > + tmp &= ~SPI_CS_HIGH;
> > + }
> > +
> > + retval = put_user(tmp & SPI_MODE_MASK, (__u8
> > __user *)arg);
> > break;
> > case SPI_IOC_RD_MODE32:
> > retval = put_user(spi->mode & SPI_MODE_MASK,
>
> What about SPI_IOC_RD_MODE_32? On the write path the code is
> shared...
you are right, thanks for this hint!
I'll re-send if there are no objections to this approach in general.
--
Alexander Sverdlin
Siemens AG
http://www.siemens.com
On Wed, Nov 30, 2022 at 03:43:27PM +0000, Sverdlin, Alexander wrote:
> On Wed, 2022-11-30 at 14:57 +0000, Mark Brown wrote:
> > What about SPI_IOC_RD_MODE_32?? On the write path the code is
> > shared...
> you are right, thanks for this hint!
> I'll re-send if there are no objections to this approach in general.
Should be fine.