| Message ID | 55AE3290.60103@compulab.co.il (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Igor, The patch you attached is okay for me. But I suggest to explain this issue more clearly. Actually it is not a no clear reason. i.MX6 platform SPI driver set MOSI and MISO in high level. You can refer to my patch log. Best Regards Haibo Chen > -----Original Message----- > From: Igor Grinberg [mailto:grinberg@compulab.co.il] > Sent: Tuesday, July 21, 2015 7:53 PM > To: Chen Haibo-B51421; dmitry.torokhov@gmail.com > Cc: jg1.han@samsung.com; pramod.gurav@smartplayin.com; linux- > input@vger.kernel.org > Subject: Re: [PATCH] Input: ads7846 - correct the value get from SPI > > Hi, > > On 05/22/15 10:02, Haibo Chen wrote: > > 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 <haibo.chen@freescale.com> > > --- > > 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; > > IIRC, 7845 is the same in regard to SPI bus, so may be we should also > adjust the value in if statement, not just the else part. > > We have the attached patch locally, so may you would like to consider it > or a mixture of both... > > > -- > Regards, > Igor. -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From fda22bb445c3866a89ef1ec876516d60f0292f7f Mon Sep 17 00:00:00 2001 From: Andrey Gelman <andrey.gelman@compulab.co.il> Date: Sun, 26 Oct 2014 17:25:43 +0200 Subject: [PATCH] input: ads7846: enforce ADC output width Enforce ADC output is 12 bits width. For no clear reason, on i.MX6-based CM-FX6, we have experienced a 13-th bit set to 1 and therefore all reported values were out of range. Signed-off-by: Andrey Gelman <andrey.gelman@compulab.co.il> [grinberg@compulab.co.il: white space, comment and commit message adjusted] Signed-off-by: Igor Grinberg <grinberg@compulab.co.il> --- 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 5196861..655ae85 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -689,18 +689,22 @@ 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])) >> 3; } 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) >> 3; } + + /* enforce ADC output is 12 bits width */ + return value & 0xfff; } static void ads7846_update_value(struct spi_message *m, int val) -- 2.3.6