Re: [RFC 1/4] Input: edt-ft5x06 - Use max support points to determine how much to read

Dmitry Torokhov
2015-10-14T23:39:11Z

On Wed, Oct 07, 2015 at 07:21:38AM -0500, fcooper@ti.com wrote:
> From: Franklin S Cooper Jr <fcooper@ti.com>
>
> Calculate the amount of data that needs to be read for the specified max
> number of support points. If the maximum number of support points changes
> then the amount that is read from the touch screen controller should
> reflect this.
>
> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
> ---
> drivers/input/touchscreen/edt-ft5x06.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
> index 7239c31..1e0ed6e 100644
> --- a/drivers/input/touchscreen/edt-ft5x06.c
> +++ b/drivers/input/touchscreen/edt-ft5x06.c
> @@ -178,14 +178,16 @@ static irqreturn_t edt_ft5x06_ts_isr(int irq, void *dev_id)
> cmd = 0xf9; /* tell the controller to send touch data */
> offset = 5; /* where the actual touch data starts */
> tplen = 4; /* data comes in so called frames */
> - datalen = 26; /* how much bytes to listen for */
> +
> + /* how many bytes to listen for */
> + datalen = tplen * MAX_SUPPORT_POINTS + offset + 1;
> break;
>
> case M09:
> cmd = 0x02;
> offset = 1;
> tplen = 6;
> - datalen = 29;
> + datalen = tplen * MAX_SUPPORT_POINTS - cmd + 1;
> break;

Hmm, why would formulae for datalen be different depending on the
firmware? And I think original 29 it too low: we need 30 bytes for 5
contacts + 1 to account for offset.

I also wonder why we need extra 1 byte in M06 case.

Lothar?

Thanks.

--
Dmitry