On Wed, Mar 19, 2014 at 01:03:45PM -0500, mrnuke wrote:
> > > - /* We don't support transfer larger than the FIFO */
> > > - if (tfr->len > SUN4I_FIFO_DEPTH)
> > > + if (tfr->len > SUN4I_MAX_XFER_SIZE)
> > > + return -EINVAL;
> >
> > Why do you still need this test?
> >
> SUN4I_MAX_XFER_SIZE is not the FIFO size. It is the max number we can write in
> SUN4I_BURST_CNT_REG. That's the maximum SPI burst size (16 MiB - 1) that the
> hardware supports. Anything larger, and we'd need to break up the transfer in
> several bursts. That's a different problem than the one I'm addressing.
Ok, it makes sense.
> > > + /* Receive FIFO 3/4 full */
> > > + if (status & SUN4I_INT_CTL_RF_F34) {
> > > + sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);
> > > + /* Only clear the interrupt _after_ draining the FIFO */
> > > + sun4i_spi_write(sspi, SUN4I_INT_STA_REG,
> > > SUN4I_INT_CTL_RF_F34);
> >
> > Not that it's important, but it really doesn't matter to do it before
> > or after, the interrupts are disabled in the handler.
> >
> I think this was one of those bits that keeps being set by hardware until the
> Rx FIFO is under 48 bytes (less than 3/4 full). I'll have to look into this
> again.
Ok, it would deserve to be in the comments then :)
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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