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Date: Wed, 27 Mar 2013 22:58:58 -0700 From: Dmitry Torokhov <dmitry.torokhov@...il.com> To: seb <sebastien.royen@...il.com> Cc: Bill Pemberton <wfp5p@...ginia.edu>, linux-kernel@...r.kernel.org, seb <sebastien.royen@...adeus.com> Subject: Re: [PATCH 1/1] Input: mma8450 - fix signed 12bits to 32bits conversion Hi Seb, On Wed, Mar 27, 2013 at 09:17:43AM +0100, seb wrote: > Event value is wrong. Should be in range -2048 to 2047, but is in range 0 to 4095. > Use int8_t to int conversion and remove 0xfff mask. > > Signed-off-by: seb <sebastien.royen@...adeus.com> > --- > drivers/input/misc/mma8450.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/input/misc/mma8450.c b/drivers/input/misc/mma8450.c > index 480557f..c3781a1 100644 > --- a/drivers/input/misc/mma8450.c > +++ b/drivers/input/misc/mma8450.c > @@ -110,7 +110,7 @@ static void mma8450_poll(struct input_polled_dev *dev) > struct mma8450 *m = dev->private; > int x, y, z; > int ret; > - u8 buf[6]; > + int8_t buf[6]; > > ret = mma8450_read(m, MMA8450_STATUS); > if (ret < 0) > @@ -119,13 +119,18 @@ static void mma8450_poll(struct input_polled_dev *dev) > if (!(ret & MMA8450_STATUS_ZXYDR)) > return; > > - ret = mma8450_read_block(m, MMA8450_OUT_X_LSB, buf, sizeof(buf)); > + ret = mma8450_read_block(m, MMA8450_OUT_X_LSB, (u8*)buf, sizeof(buf)); > if (ret < 0) > return; > > - x = ((buf[1] << 4) & 0xff0) | (buf[0] & 0xf); > - y = ((buf[3] << 4) & 0xff0) | (buf[2] & 0xf); > - z = ((buf[5] << 4) & 0xff0) | (buf[4] & 0xf); > + /* convert 8 MSB from int8_t to int */ > + x = buf[1]; > + y = buf[3]; > + z = buf[5]; > + /* add 4 LSB */ > + x = (x << 4) | (buf[0] & 0xf); > + y = (y << 4) | (buf[2] & 0xf); > + z = (z << 4) | (buf[4] & 0xf); Should we just say: x = ((int)(s8)buf[1] << 4) | (buf[0] & 0xf); y = ... z = ... and leave the rest as is? Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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