Hi,
On Mon, 18 May 2015 15:55:00 +0300
Evgeniy Dushistov <dushistov@xxxxxxx> wrote:
> CC me please, I'm not subscribed to any linux-kernel list.
>
> Hi,
> recently I have ads7845 device connected to my beagleboard,
> and I try to use ads7846 to work with it.
> But it fails, it show completely wrong x/y.
>
> But, after I disabled almost all code that related to ads7845 ("== 7845"),
> except determination of amount of pressure force,
> all start works as expected,
> I found such commit:
>
> >commit 3eac5c7e44f35eb07f0ecb28ce60f15b2dda1932
> >Author: Anatolij Gustschin <agust@xxxxxxx>
> >...
> >ADS7845 is a controller for 5-wire touch screens and somewhat
> >different from 7846. It requires three serial communications to
> >accomplish one complete conversion.
> >...
>
> But according to datasheets:
> http://www.ti.com/lit/ds/symlink/ads7846.pdf
> http://www.ti.com/lit/ds/symlink/ads7845.pdf
>
> ads7845(page 8) and ads7846 (page 12) have
> identical digital interfaces, I attach quotes
> from them in text from to this email.
>
> So why spi negotiation for ads7845 require special code,
> except
> >Z1-/Z2- position measurement
>
> Was this commit tested? May be you test
> in some special mode, like 15 vs 16 bits?
this was tested, but if I remember correctly, on some ppc board were
multi-segment SPI transfers didn't work (SPI chip-select disabled by
controller after first SPI command byte). I do not know any more if it
was the only reason for this ads7845 specific handling in my commit
and unfortunately I do not have this board to check it again.
> Here is working for me patch (it against 3.16,
> but applied to Linus's git master also).
>
> ads7846: fix to force ads7846 driver works with ads7845
> device
Then can you please first revert my patch and then add the only
code that is needed to work with ads7845 ? After this you can
squash both parts to a single commit and submit a clean patch.
Thanks,
Anatolij
> Signed-off-by: Evgneiy A. Dushistov <dushistov@xxxxxxx>
> ---
> drivers/input/touchscreen/ads7846.c | 21 +++++++++++----------
> 1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
> index da201b8..27f4796 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -17,6 +17,9 @@
> * it under the terms of the GNU General Public License version 2 as
> * published by the Free Software Foundation.
> */
> +#define VERBOSE_DEBUG
> +#define DEBUG
> +
> #include <linux/types.h>
> #include <linux/hwmon.h>
> #include <linux/err.h>
> @@ -671,14 +674,14 @@ static int ads7846_get_value(struct ads7846 *ts, struct spi_message *m)
> struct spi_transfer *t =
> list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
>
> - if (ts->model == 7845) {
> + if (0/*ts->model == 7845*/) {
> return 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;
> + return (be16_to_cpup((__be16 *)t->rx_buf) & 0x7fff) >> 3;
> }
> }
>
> @@ -755,14 +758,12 @@ static void ads7846_report_state(struct ads7846 *ts)
> * from on-the-wire format as part of debouncing to get stable
> * readings.
> */
> + x = packet->tc.x;
> + y = packet->tc.y;
> if (ts->model == 7845) {
> - x = *(u16 *)packet->tc.x_buf;
> - y = *(u16 *)packet->tc.y_buf;
> z1 = 0;
> z2 = 0;
> } else {
> - x = packet->tc.x;
> - y = packet->tc.y;
> z1 = packet->tc.z1;
> z2 = packet->tc.z2;
> }
> @@ -995,7 +996,7 @@ static void ads7846_setup_spi_msg(struct ads7846 *ts,
> spi_message_init(m);
> m->context = ts;
>
> - if (ts->model == 7845) {
> + if (0/*ts->model == 7845*/) {
> packet->read_y_cmd[0] = READ_Y(vref);
> packet->read_y_cmd[1] = 0;
> packet->read_y_cmd[2] = 0;
> @@ -1040,7 +1041,7 @@ static void ads7846_setup_spi_msg(struct ads7846 *ts,
> spi_message_init(m);
> m->context = ts;
>
> - if (ts->model == 7845) {
> + if (0/*ts->model == 7845*/) {
> x++;
> packet->read_x_cmd[0] = READ_X(vref);
> packet->read_x_cmd[1] = 0;
> @@ -1149,7 +1150,7 @@ static void ads7846_setup_spi_msg(struct ads7846 *ts,
> spi_message_init(m);
> m->context = ts;
>
> - if (ts->model == 7845) {
> + if (0/*ts->model == 7845*/) {
> x++;
> packet->pwrdown_cmd[0] = PWRDOWN;
> packet->pwrdown_cmd[1] = 0;
> @@ -1408,7 +1409,7 @@ static int ads7846_probe(struct spi_device *spi)
> * Take a first sample, leaving nPENIRQ active and vREF off; avoid
> * the touchscreen, in case it's not connected.
> */
> - if (ts->model == 7845)
> + if (0/*ts->model == 7845*/)
> ads7845_read12_ser(&spi->dev, PWRDOWN);
> else
> (void) ads7846_read12_ser(&spi->dev, READ_12BIT_SER(vaux));
--
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