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> -----Original Message----- > From: Haibo Chen [mailto:[email protected]] > Sent: Friday, May 22, 2015 3:02 PM > To: [email protected] > Cc: [email protected]; [email protected]; linux- > [email protected]; Chen Haibo-B51421 > Subject: [PATCH] Input: ads7846 - correct the value get from SPI > > 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 configed when SPI in idle mode. > Currently this touch driver consider the SPI bus set the MOSI and MISO in > low level when SPI bus in idle mode. So the bit[15] of the value get from > SPI bus is always 0. But when SPI bus congfig the MOSI and MISO in high > level when SPI in idle mode, the bit[15] of the value get from SPI is > always 1, if not mask this bit[15], we may get the wrong value. > > This patch mask the invalid bit, and make sure to return the correct > value nomatter how SPI bus configed. > > Signed-off-by: Haibo Chen <[email protected]> > --- > 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 e4eb8a6..91b335f 100644 > --- a/drivers/input/touchscreen/ads7846.c > +++ b/drivers/input/touchscreen/ads7846.c > @@ -678,7 +678,7 @@ static int ads7846_get_value(struct ads7846 *ts, > struct spi_message *m) > * 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; > + return (be16_to_cpup((__be16 *)t->rx_buf) & 0x7ff8) >> 3; > } > } > > -- > 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
