diff mbox series

spi: bcm2835: fix gpio cs level inversion

Message ID 20201014090230.2706810-1-martin@geanix.com
State Accepted
Commit 5e31ba0c0543a04483b53151eb5b7413efece94c
Headers show
Series spi: bcm2835: fix gpio cs level inversion | expand

Commit Message

Martin Hundebøll Oct. 14, 2020, 9:02 a.m. UTC
The work on improving gpio chip-select in spi core, and the following
fixes, has caused the bcm2835 spi driver to use wrong levels. Fix this
by simply removing level handling in the bcm2835 driver, and let the
core do its work.

Fixes: 3e5ec1db8bfe ("spi: Fix SPI_CS_HIGH setting when using native and GPIO CS")
Cc: <stable@vger.kernel.org>
Signed-off-by: Martin Hundebøll <martin@geanix.com>
---
 drivers/spi/spi-bcm2835.c | 12 ------------
 1 file changed, 12 deletions(-)

Comments

Nathan Chancellor Oct. 30, 2020, 9:06 a.m. UTC | #1
On Wed, Oct 14, 2020 at 11:02:30AM +0200, Martin Hundebøll wrote:
> The work on improving gpio chip-select in spi core, and the following

> fixes, has caused the bcm2835 spi driver to use wrong levels. Fix this

> by simply removing level handling in the bcm2835 driver, and let the

> core do its work.

> 

> Fixes: 3e5ec1db8bfe ("spi: Fix SPI_CS_HIGH setting when using native and GPIO CS")

> Cc: <stable@vger.kernel.org>

> Signed-off-by: Martin Hundebøll <martin@geanix.com>

> ---

>  drivers/spi/spi-bcm2835.c | 12 ------------

>  1 file changed, 12 deletions(-)

> 

> diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c

> index b87116e9b413..9b6ba94fe878 100644

> --- a/drivers/spi/spi-bcm2835.c

> +++ b/drivers/spi/spi-bcm2835.c

> @@ -1259,18 +1259,6 @@ static int bcm2835_spi_setup(struct spi_device *spi)

>  	if (!chip)

>  		return 0;

>  

> -	/*

> -	 * Retrieve the corresponding GPIO line used for CS.

> -	 * The inversion semantics will be handled by the GPIO core

> -	 * code, so we pass GPIOD_OUT_LOW for "unasserted" and

> -	 * the correct flag for inversion semantics. The SPI_CS_HIGH

> -	 * on spi->mode cannot be checked for polarity in this case

> -	 * as the flag use_gpio_descriptors enforces SPI_CS_HIGH.

> -	 */

> -	if (of_property_read_bool(spi->dev.of_node, "spi-cs-high"))

> -		lflags = GPIO_ACTIVE_HIGH;

> -	else

> -		lflags = GPIO_ACTIVE_LOW;

>  	spi->cs_gpiod = gpiochip_request_own_desc(chip, 8 - spi->chip_select,

>  						  DRV_NAME,

>  						  lflags,

> -- 

> 2.28.0

> 

> 


Clang now warns:

drivers/spi/spi-bcm2835.c:1264:9: warning: variable 'lflags' is uninitialized when used here [-Wuninitialized]
                                                  lflags,
                                                  ^~~~~~
drivers/spi/spi-bcm2835.c:1196:2: note: variable 'lflags' is declared here
        enum gpio_lookup_flags lflags;
        ^
1 warning generated.

Cheers,
Nathan
Mark Brown Nov. 5, 2020, 3:08 p.m. UTC | #2
On Thu, Nov 05, 2020 at 10:06:15AM +0100, Martin Hundebøll wrote:
> Removing the duplicate gpio chip select level handling in
> bcm2835_spi_setup() left the lflags variable uninitialized. Avoid trhe
> use of such variable by passing default flags to
> gpiochip_request_own_desc().

Please don't send patches in reply to old threads, it buries them and
can make it unclear what is a new patch which needs review.  Send new
patches as new threads.
diff mbox series

Patch

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index b87116e9b413..9b6ba94fe878 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -1259,18 +1259,6 @@  static int bcm2835_spi_setup(struct spi_device *spi)
 	if (!chip)
 		return 0;
 
-	/*
-	 * Retrieve the corresponding GPIO line used for CS.
-	 * The inversion semantics will be handled by the GPIO core
-	 * code, so we pass GPIOD_OUT_LOW for "unasserted" and
-	 * the correct flag for inversion semantics. The SPI_CS_HIGH
-	 * on spi->mode cannot be checked for polarity in this case
-	 * as the flag use_gpio_descriptors enforces SPI_CS_HIGH.
-	 */
-	if (of_property_read_bool(spi->dev.of_node, "spi-cs-high"))
-		lflags = GPIO_ACTIVE_HIGH;
-	else
-		lflags = GPIO_ACTIVE_LOW;
 	spi->cs_gpiod = gpiochip_request_own_desc(chip, 8 - spi->chip_select,
 						  DRV_NAME,
 						  lflags,