| Message ID | 1444140010-23939-1-git-send-email-grinberg@compulab.co.il (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Tue, Oct 06, 2015 at 05:00:10PM +0300, Igor Grinberg wrote: > From: Andrey Gelman <andrey.gelman@compulab.co.il> > > According to the touch controller spec, SPI return a 16 bit value, > only 12 bits are valid, they are bit[14-3]. > > The value of MISO and MOSI can be configured when SPI is in idle mode. > Currently this touch driver assumes the SPI bus sets the MOSI and > MISO in low level when SPI bus is in idle mode. So the bit[15] of the > value got from SPI bus is always 0. But when SPI bus congfigures the > MOSI and MISO in high level during the SPI idle mode, the bit[15] of > the value get from SPI is always 1. If bit[15] is not masked, we may > get the wrong value. > > Mask the invalid bit to make sure the correct value gets returned. > Regardless of the SPI bus idle configuration. > > Signed-off-by: Andrey Gelman <andrey.gelman@compulab.co.il> > Signed-off-by: Haibo Chen <haibo.chen@freescale.com> > Signed-off-by: Igor Grinberg <grinberg@compulab.co.il> Applied, thank you. > --- > drivers/input/touchscreen/ads7846.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c > index 727d88c..8e2a44d 100644 > --- a/drivers/input/touchscreen/ads7846.c > +++ b/drivers/input/touchscreen/ads7846.c > @@ -666,18 +666,22 @@ static int ads7846_no_filter(void *ads, int data_idx, int *val) > > static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m) > { > + int value; > struct spi_transfer *t = > list_entry(m->transfers.prev, struct spi_transfer, transfer_list); > > if (ts->model == 7845) { > - return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3; > + value = be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])); > } else { > /* > * adjust: on-wire is a must-ignore bit, a BE12 value, then > * padding; built from two 8 bit values written msb-first. > */ > - return be16_to_cpup((__be16 *)t->rx_buf) >> 3; > + value = be16_to_cpup((__be16 *)t->rx_buf); > } > + > + /* enforce ADC output is 12 bits width */ > + return (value >> 3) & 0xfff; > } > > static void ads7846_update_value(struct spi_message *m, int val) > -- > 2.4.9 >
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index 727d88c..8e2a44d 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -666,18 +666,22 @@ static int ads7846_no_filter(void *ads, int data_idx, int *val) static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m) { + int value; struct spi_transfer *t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list); if (ts->model == 7845) { - return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3; + value = be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])); } else { /* * adjust: on-wire is a must-ignore bit, a BE12 value, then * padding; built from two 8 bit values written msb-first. */ - return be16_to_cpup((__be16 *)t->rx_buf) >> 3; + value = be16_to_cpup((__be16 *)t->rx_buf); } + + /* enforce ADC output is 12 bits width */ + return (value >> 3) & 0xfff; } static void ads7846_update_value(struct spi_message *m, int val)