[PATCH] input: wacom: Fix physical size calculation for 3rd-gen Bamboo

[PATCH] input: wacom: Fix physical size calculation for 3rd-gen Bamboo

[Jason Gerecke]

This calculation determines the physical dimensions of the tablet,
used later on in calculate_touch_res to obtain the touch sensor
resolution.

Instead of dividing the logical size by the resolution, the current
code performs a multiplication. This doesn't pose a problem for the
3rd-gen Bamboo since the resolution and scale factor happen to be
identical, but will produce an incorrect result for other cases.

Signed-off-by: Jason Gerecke <killertofu@gmail.com>
---
 drivers/input/tablet/wacom_sys.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/tablet/wacom_sys.c b/drivers/input/tablet/wacom_sys.c
index c9588ee..dc07821 100644
--- a/drivers/input/tablet/wacom_sys.c
+++ b/drivers/input/tablet/wacom_sys.c
@@ -184,9 +184,9 @@ static int wacom_parse_logical_collection(unsigned char *report,
 		 * data before its overwritten.
 		 */
 		features->x_phy =
-			(features->x_max * features->x_resolution) / 100;
+			(features->x_max * 100) / features->x_resolution;
 		features->y_phy =
-			(features->y_max * features->y_resolution) / 100;
+			(features->y_max * 100) / features->y_resolution;
 
 		features->x_max = features->y_max =
 			get_unaligned_le16(&report[10]);
-- 
1.7.9.1

Re: [PATCH] input: wacom: Fix physical size calculation for 3rd-gen Bamboo

[Chris Bagwell]

On Mon, Mar 12, 2012 at 5:53 PM, Jason Gerecke <killertofu@gmail.com> wrote:
> This calculation determines the physical dimensions of the tablet,
> used later on in calculate_touch_res to obtain the touch sensor
> resolution.
>
> Instead of dividing the logical size by the resolution, the current
> code performs a multiplication. This doesn't pose a problem for the
> 3rd-gen Bamboo since the resolution and scale factor happen to be
> identical, but will produce an incorrect result for other cases.
>
> Signed-off-by: Jason Gerecke <killertofu@gmail.com>

Reviewed-by: Chris Bagwell <chris@cnpbagwell.com>

> ---
>  drivers/input/tablet/wacom_sys.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/tablet/wacom_sys.c b/drivers/input/tablet/wacom_sys.c
> index c9588ee..dc07821 100644
> --- a/drivers/input/tablet/wacom_sys.c
> +++ b/drivers/input/tablet/wacom_sys.c
> @@ -184,9 +184,9 @@ static int wacom_parse_logical_collection(unsigned char *report,
>                 * data before its overwritten.
>                 */
>                features->x_phy =
> -                       (features->x_max * features->x_resolution) / 100;
> +                       (features->x_max * 100) / features->x_resolution;
>                features->y_phy =
> -                       (features->y_max * features->y_resolution) / 100;
> +                       (features->y_max * 100) / features->y_resolution;
>
>                features->x_max = features->y_max =
>                        get_unaligned_le16(&report[10]);
> --
> 1.7.9.1
>
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Re: [PATCH] input: wacom: Fix physical size calculation for 3rd-gen Bamboo

[Dmitry Torokhov]

On Mon, Mar 12, 2012 at 10:25:47PM -0500, Chris Bagwell wrote:
> On Mon, Mar 12, 2012 at 5:53 PM, Jason Gerecke <killertofu@gmail.com> wrote:
> > This calculation determines the physical dimensions of the tablet,
> > used later on in calculate_touch_res to obtain the touch sensor
> > resolution.
> >
> > Instead of dividing the logical size by the resolution, the current
> > code performs a multiplication. This doesn't pose a problem for the
> > 3rd-gen Bamboo since the resolution and scale factor happen to be
> > identical, but will produce an incorrect result for other cases.
> >
> > Signed-off-by: Jason Gerecke <killertofu@gmail.com>
> 
> Reviewed-by: Chris Bagwell <chris@cnpbagwell.com>

Applied, thank you.

-- 
Dmitry