SPI: DUAL/QUAD support

[yuhang wang]

> To add to all the discussion going on,
> I am using a qspi controller with a spansion flash device.
> I tried using quad read mode bit, and what is required to change in
> my case is the following:
>
> 1. enable quad mode in flash configuration register.
> 2. change my read opcode to QUAD READ opcode according to flash datasheet.
> 3. Configure my qspi controller cmd reg to use 6 PIN whenever quad mode is
> used.
>

Sorry, to the third point I am still not very clear. The first time,
spi controller should send
QUAD READ opcode to your spansion flash with 1 line, then receive datas from
flash with 4 lines. So how does your controller master this process
automatically.

Please give me some details.

Thanks