[U-Boot] [PATCH] NET: add ENC28J60 driver using SPI framework

[Reinhard Meyer]

On 04.09.2010 00:14, Mike Frysinger wrote:
> On Friday, September 03, 2010 17:23:43 Reinhard Meyer wrote:
>> On 03.09.2010 23:03, Mike Frysinger wrote:
>>>> not sure, however, if calling spi_setup_slave() is ok at this point.
>>>
>>> i believe the func should only doing validation on the arguments.  it
>>> shouldnt need to talk to any actual hardware.  maybe this needs
>>> codifying in the API documentation.
>>
>> In atmel_spi.c it sets up the csr[indexed by cs=0..3] register with clock,
>> phase and polarity.
>> That's harmless, but might need some rethinking there.
>
> i'm not familiar with the Atmel SPI controller, but my gut reaction is that
> register values should be calculated in spi_setup_slave(), stored in the
> internal xxx_spi_slave struct, and then written at spi_claim_bus() time.
> -mike
Well, the SPI hardware can store the settings for 4 chip selects, and quite
automagically switch between them, including programmable switch times. When
using DMA it would be possible to setup transfers to/from different chip
selects without software doing the switches, ex:
15 words of 13 bits using 199kHz and mode 3 via CS2,
2 words of 8 bits using 10MHz and mode 0 via CS3, etc...
All this, of course, is not needed in u-boot and currently only half used
anyway. Therefore I tend to rework the atmel_spi.c not to make use of that
feature at all.

For codig the ENC driver I will just postulate its save to setup the slave
at initialize time.

Reinhard