Re: problem with converting from at91_spi to atmel_spi (AT91RM9200)

[Ivan Kuten <ivan.kuten-NihHnkIkDZhBDgjK7y7TUQ@public.gmane.org>]

On Wed, 23 May 2007 09:06:12 -0700
David Brownell wrote:
> 
> Chipselect zero ... I've had one report that this driver has some issues
> on that chipselect.  There seem to be two errata in conflict here:
> 
>   - One saying that when the controller manages chipselects, it
>     does so incorrectly ... releasing it before it's told to do so,
>     which prematurely terminates transactions.  ("NPCSx rises if
>     no data is to be transmitted")
> 
>   - Another saying that if it does *not* manage chipselects, then
>     broken mode fault detect logic kicks in; this could be what
>     you're seeing.  ("Mode Fault does not allow more than one
>     master on Chip Select 0")
> 

David, as I understood new atmel_spi driver enables CONFIG_SPI_AT91_MANUAL_CS
which in turn enables workaround for 1st errata item you mentioned

at91rm9200_devices.c
...
in at91_add_device_spi function:

#ifdef CONFIG_SPI_AT91_MANUAL_CS 
                at91_set_gpio_output(cs_pin, 1);
#else 
                at91_set_A_periph(cs_pin, 0);
#endif 

Regarding second errata item - I have a single device (dataflash - 8MB) on SPI chip select 0, 
so I do not think this is an issue here.

Best regards, Ivan


-------------------------------------------------------------------------
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/