Re: TSC2101/2102

[Imre Deak <imre.deak@solidboot.com>]

On Fri, Mar 16, 2007 at 05:05:58PM +0900, Kyungmin Park wrote:
> 
> > > > 
> > > > I needed only the basic register read / write interface to access 
> > > > the
> > > > TSC2101 GPIO lines. The TS part you wrote is still 
> > needed, it's init 
> > > > function being called from the tsc2101.c probe, as it's done in 
> > > > tsc2301-core.c.
> > > > 
> > > > > The current code only supports 16-bit tsc2101 for OMAP1.
> > > > > We have to consider OMAP2 tsc2101 for H4 and apollon.
> > > > 
> > > > Is the 32-bit interface some alternate interface 
> > configuration for 
> > > > the chip?
> > > 
> > > No. it's only needed in SPI protocol.
> > > 
> > > I don't know it's possible to use 16-bit mode in OMAP2. but most 
> > > driver which uses tsc2101 on OMAP2 uses 32-bit access.
> > 
> > The following is an example how you setup the transfer for 32-bit
> > transfer:
> > 
> > +static void tsc2101_ts_setup_spi_xfer(struct tsc2101 *tsc) {
> > +	struct tsc2101_ts *ts = tsc->ts;
> > +	struct spi_message *m = &ts->read_msg;
> > +	struct spi_transfer *x = &ts->read_xfer[0];
> > +
> > +	ts->address[0] = (0x8000 | TSC2101_REG_X) << 16;
> > +	ts->address[1] = (0x8000 | TSC2101_REG_Y) << 16;
> > +	ts->address[2] = (0x8000 | TSC2101_REG_Z1) << 16;
> > +	ts->address[3] = (0x8000 | TSC2101_REG_Z2) << 16;
> > +
> > +	spi_message_init(m);
> > +
> > +	x->tx_buf = &ts->address;
> > +	x->rx_buf = &ts->data;
> > +	x->len = 16;
> > +	spi_message_add_tail(x, m);
> > +
> > +	m->complete = tsc2101_ts_rx;
> > +	m->context = tsc;
> > +}
> > 
> > While this may work, I'm not sure the driver should have 
> > support for such an alternate protocol. What's the benifit of 
> > it? The TSC2xxx chips have a register address auto increment 
> > feature, so you need to send only the starting address and 
> > then do a read for each consecutive registers. Did you try 
> > the 16-bit mode in SPI_MODE_0 as it's done in the TSC2301 driver?
> 
> No, it's not work if we provide the one address
> 
> /* XXX: tsc2101 specific */
> static const u32 tsc2101_ts_read_data[4] = {
>         (0x8000 | TSC2101_REG_X) << 16,
>         (0x8000 | TSC2101_REG_Y) << 16,
>         (0x8000 | TSC2101_REG_Z1) << 16,
>         (0x8000 | TSC2101_REG_Z2) << 16,
> };
> 
> static void tsc2101_ts_setup_spi_xfer(struct tsc2101 *tsc)
> {
>         struct tsc2101_ts *ts = tsc->ts;
>         struct spi_message *m = &ts->read_msg;
>         struct spi_transfer *x = &ts->read_xfer[0];
> 
>         spi_message_init(m);
> 
>         x->tx_buf = &tsc2101_ts_read_data;
>         x->rx_buf = &ts->data;
>         x->len = 16;
>         spi_message_add_tail(x, m);
> 
>         m->complete = tsc2101_ts_rx;
>         m->context = tsc;
> }
> 
> No, I don't try to use 16-bit mode. since it's working well 32-bit mode, I
> just use it for a long time.

Could you try it with debugging enabled in omap2_mcspi? Would be interesting
to see where the problem is.

--Imre
>