| Message ID | 20210707124115.20028-1-o.rempel@pengutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1] Input: ads7846: ads7846_get_value - fix unaligned pointer value warning | expand |
Hi Oleksij, On Wed, Jul 07, 2021 at 02:41:15PM +0200, Oleksij Rempel wrote: > Fix warning reported by the kernel test robot: > drivers/input/touchscreen/ads7846.c:705:24: warning: taking address > of packed member 'data' of class or structure 'ads7846_buf' may result > in an unaligned pointer value [-Waddress-of-packed-member] > > Fixes: 6965eece2a89 ("Input: ads7846 - convert to one message") > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > --- > drivers/input/touchscreen/ads7846.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c > index adb4c2230c31..1987dedac94f 100644 > --- a/drivers/input/touchscreen/ads7846.c > +++ b/drivers/input/touchscreen/ads7846.c > @@ -702,7 +702,7 @@ static int ads7846_get_value(struct ads7846_buf *buf) > { > int value; > > - value = be16_to_cpup(&buf->data); > + value = get_unaligned_be16(&buf->data); ds7846_buf is declared as packed so I believe using be16_to_cpu(buf->data) will suffice. I can adjust on my side if you agree. Thanks.
Hi Dmitry, On Thu, Sep 09, 2021 at 10:04:16PM -0700, Dmitry Torokhov wrote: > Hi Oleksij, > > On Wed, Jul 07, 2021 at 02:41:15PM +0200, Oleksij Rempel wrote: > > Fix warning reported by the kernel test robot: > > drivers/input/touchscreen/ads7846.c:705:24: warning: taking address > > of packed member 'data' of class or structure 'ads7846_buf' may result > > in an unaligned pointer value [-Waddress-of-packed-member] > > > > Fixes: 6965eece2a89 ("Input: ads7846 - convert to one message") > > Reported-by: kernel test robot <lkp@intel.com> > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > > --- > > drivers/input/touchscreen/ads7846.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c > > index adb4c2230c31..1987dedac94f 100644 > > --- a/drivers/input/touchscreen/ads7846.c > > +++ b/drivers/input/touchscreen/ads7846.c > > @@ -702,7 +702,7 @@ static int ads7846_get_value(struct ads7846_buf *buf) > > { > > int value; > > > > - value = be16_to_cpup(&buf->data); > > + value = get_unaligned_be16(&buf->data); > > ds7846_buf is declared as packed so I believe using be16_to_cpu(buf->data) > will suffice. The pointer to the data is is off by 8 bits, so it is not naturally aligned. This is why we need to use function which is dealing with unaligned pointers. Regards, Oleksij
On Fri, Sep 10, 2021 at 09:51:54AM +0200, Oleksij Rempel wrote: > Hi Dmitry, > > On Thu, Sep 09, 2021 at 10:04:16PM -0700, Dmitry Torokhov wrote: > > Hi Oleksij, > > > > On Wed, Jul 07, 2021 at 02:41:15PM +0200, Oleksij Rempel wrote: > > > Fix warning reported by the kernel test robot: > > > drivers/input/touchscreen/ads7846.c:705:24: warning: taking address > > > of packed member 'data' of class or structure 'ads7846_buf' may result > > > in an unaligned pointer value [-Waddress-of-packed-member] > > > > > > Fixes: 6965eece2a89 ("Input: ads7846 - convert to one message") > > > Reported-by: kernel test robot <lkp@intel.com> > > > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> > > > --- > > > drivers/input/touchscreen/ads7846.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c > > > index adb4c2230c31..1987dedac94f 100644 > > > --- a/drivers/input/touchscreen/ads7846.c > > > +++ b/drivers/input/touchscreen/ads7846.c > > > @@ -702,7 +702,7 @@ static int ads7846_get_value(struct ads7846_buf *buf) > > > { > > > int value; > > > > > > - value = be16_to_cpup(&buf->data); > > > + value = get_unaligned_be16(&buf->data); > > > > ds7846_buf is declared as packed so I believe using be16_to_cpu(buf->data) > > will suffice. > > The pointer to the data is is off by 8 bits, so it is not naturally > aligned. This is why we need to use function which is dealing with > unaligned pointers. As I mentioned, the structure is packed, so the compiler will take care of doing unaligned access safely on architectures that can not tolerate it. Thanks.
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index adb4c2230c31..1987dedac94f 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -702,7 +702,7 @@ static int ads7846_get_value(struct ads7846_buf *buf) { int value; - value = be16_to_cpup(&buf->data); + value = get_unaligned_be16(&buf->data); /* enforce ADC output is 12 bits width */ return (value >> 3) & 0xfff;
Fix warning reported by the kernel test robot: drivers/input/touchscreen/ads7846.c:705:24: warning: taking address of packed member 'data' of class or structure 'ads7846_buf' may result in an unaligned pointer value [-Waddress-of-packed-member] Fixes: 6965eece2a89 ("Input: ads7846 - convert to one message") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de> --- drivers/input/touchscreen/ads7846.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)