[PATCH] libertas: check valid bits in SPI bus mode reg

[PATCH] libertas: check valid bits in SPI bus mode reg

[Andrey Yurovsky]

The SPI driver writes to the bus mode register and performs a sanity
check by reading back what we wrote, however only the lower four bits of
that register are defined.  In some cases, the device side seems to set
the higher bits, causing us to fail the sanity check unnecessarily.
Check only the lower four bits instead.

Thanks to John Goyette from Schick Technologies for pointing out the
problem.

Signed-off-by: Andrey Yurovsky <andrey@cozybit.com>
---
 drivers/net/wireless/libertas/if_spi.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/wireless/libertas/if_spi.c b/drivers/net/wireless/libertas/if_spi.c
index 6564282..86263a9 100644
--- a/drivers/net/wireless/libertas/if_spi.c
+++ b/drivers/net/wireless/libertas/if_spi.c
@@ -376,7 +376,7 @@ static int spu_set_bus_mode(struct if_spi_card *card, u16 mode)
 	err = spu_read_u16(card, IF_SPI_SPU_BUS_MODE_REG, &rval);
 	if (err)
 		return err;
-	if (rval != mode) {
+	if ((rval & 0xF) != mode) {
 		lbs_pr_err("Can't read bus mode register.\n");
 		return -EIO;
 	}
-- 
1.5.6.3

Re: [PATCH] libertas: check valid bits in SPI bus mode reg

[Dan Williams]

On Fri, 2009-07-31 at 11:35 -0700, Andrey Yurovsky wrote:
> The SPI driver writes to the bus mode register and performs a sanity
> check by reading back what we wrote, however only the lower four bits of
> that register are defined.  In some cases, the device side seems to set
> the higher bits, causing us to fail the sanity check unnecessarily.
> Check only the lower four bits instead.
> 
> Thanks to John Goyette from Schick Technologies for pointing out the
> problem.
> 
> Signed-off-by: Andrey Yurovsky <andrey@cozybit.com>

Acked-by: Dan Williams <dcbw@redhat.com>

> ---
>  drivers/net/wireless/libertas/if_spi.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/wireless/libertas/if_spi.c b/drivers/net/wireless/libertas/if_spi.c
> index 6564282..86263a9 100644
> --- a/drivers/net/wireless/libertas/if_spi.c
> +++ b/drivers/net/wireless/libertas/if_spi.c
> @@ -376,7 +376,7 @@ static int spu_set_bus_mode(struct if_spi_card *card, u16 mode)
>  	err = spu_read_u16(card, IF_SPI_SPU_BUS_MODE_REG, &rval);
>  	if (err)
>  		return err;
> -	if (rval != mode) {
> +	if ((rval & 0xF) != mode) {
>  		lbs_pr_err("Can't read bus mode register.\n");
>  		return -EIO;
>  	}