Re: [PATCH] input/spi: add ads7843 support to ads7846 touchscreen driver

[Nicolas Ferre <nicolas.ferre@rfo.atmel.com>]

David Brownell :
> Did you find out what was causing the jerky behavior (draw a circle,
> it looks like a square) before?

No, my previous rework based on your patches (2.6.19) had this
jerky behavior. I was obliged to go back to old style timers.
On this build, with the htimer framework, it seems ok.
 
> > -	/* maybe off internal vREF */
> > -	if (use_internal) {
>
> This part doesn't make sense.  Could you say what you're trying
> to do?  The ads7846 requres an external vREF.  Is the issue that
> maybe the REF_OFF command isn't just turning off the (non-existent)
> internal voltage reference?  If so the comments need updating, and
> maybe the name REF_OFF needs to change too...

Well, on the ads7843, this command allow to put converter in low power
mode and, more important, enable the PENIRQ (otherwise disabled).

The REF_OFF command can be replaced by the PWRDOWN one (exactly the
same command). This last name matches better the ads7843
datasheet description (and seems ok considering the ads7846 one).

> > -		req->ref_off = REF_OFF;
> > -		req->xfer[4].tx_buf = &req->ref_off;
> > -		req->xfer[4].len = 1;
> > -		spi_message_add_tail(&req->xfer[4], &req->msg);
> > -
> > -		req->xfer[5].rx_buf = &req->scratch;
> > -		req->xfer[5].len = 2;
> > -		CS_CHANGE(req->xfer[5]);
> > -		spi_message_add_tail(&req->xfer[5], &req->msg);
> > -	}
> > +	req->ref_off = REF_OFF;
> > +	req->xfer[4].tx_buf = &req->ref_off;
> > +	req->xfer[4].len = 1;
> > +	spi_message_add_tail(&req->xfer[4], &req->msg);
> > +
> > +	req->xfer[5].rx_buf = &req->scratch;
> > +	req->xfer[5].len = 2;
> > +	CS_CHANGE(req->xfer[5]);
> > +	spi_message_add_tail(&req->xfer[5], &req->msg);
> >  
> >  	ts->irq_disabled = 1;
> >  	disable_irq(spi->irq);

Regards,
--
Nicolas Ferre


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