[alsa-devel] [PATCH] EDB93xx: Add support for CS4271 CODEC on EDB93xx boards

[H Hartley Sweeten]

On Wednesday, February 02, 2011 10:33 AM, Alexander Sverdlin wrote:
> It's a chip select. The way I've managed it in CODEC it's because Cirrus
> boards do not have any other SPI devices. Supported by current mainline,
> at least.

All the EDB93xx boards also have an spi flash device.  And there are a
couple drivers in mainline that can be used.  Depending on the actual spi
flash device: drivers/mtd/m25p80.c, drivers/mtd/sst25l.c, or 
/drivers/misc/eeprom/at25.c.

There are a couple patches floating around to add the spi flash support
to the edb93xx platform init but nothing is merged yet.

BTW, you really should remove the or-gate's that Cirrus used with the spi
chip-selects to logically-and the SFRM and GPIO signals.  The SFRM signal
deasserts when the spi fifo's empty which could cause a chip-select 
deassertion to the chip in the middle of a transfer.  For the spi flash,
this breaks any read's from the device.  Just connect the gpio line
directly to the chip-select of the device.

Regards,
Hartley