On Thu, 23 Jun 2011 11:01:25 +0800
Dirk Brandewie <[email protected]> wrote:
> >> - /*
> >> - * Try to detect the FIFO depth if not set by interface
> >> driver,
> >> - * the depth could be from 2 to 256 from HW spec
> >> - */
> >> - if (!dws->fifo_len) {
> >> - u32 fifo;
> >> - for (fifo = 2; fifo<= 257; fifo++) {
> >> - dw_writew(dws, txfltr, fifo);
> >> - if (fifo != dw_readw(dws, txfltr))
> >> - break;
> >> - }
> >> -
> >> - dws->fifo_len = (fifo == 257) ? 0 : fifo;
> >> - dw_writew(dws, txfltr, 0);
> >> - }
> >> }
> >
> > This code is requested by other community developers, the FIFO
> > length is adjustable for the dw_spi core when deployed on
> > different platforms, for those who are not certain about the
> > FIFO len, they can use this code to probe the FIFO len.
> >
> > So we need to keep it.
> >
>
> Then I have bad documentation because document I have says that you
> can NOt write to txfltr while the controller is enabled. The sizing
> routine as it stands can't work for the implementation in Moorsetown
> and Medfield.
>
> If there are other SOC's that are implementing different semantics
> for txfltr we will need to handle this differently and do some
> runtime detection of how the fifo should be sized.
>
> Can you give ne a reference to the person that requiested the sizing
> code so I can follow-up
Git-show c587b6fa0510
commit c587b6fa05106606053fc5e8e344f07cd34ace23
Author: Feng Tang <[email protected]>
Date: Thu Jan 21 10:41:10 2010 +0800
spi/dw_spi: add a FIFO depth detection
FIFO depth is configurable for each implementation of DW core,
so add a depth detection for those interface drivers who don't set
the fifo_len explicitly
Signed-off-by: Feng Tang <[email protected]>
Acked-by: Jean-Hugues Deschenes <[email protected]>
Signed-off-by: Grant Likely <[email protected]>
I added the code per request from Jean-Hugues Deschenes.
Recently Alek Du has tested this code on his Medfield platform.
Thanks,
Feng
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