[PATCHv2] drivers: mtd: devices: Add quad read support.

[Huang Shijie]

于 2013年09月27日 13:54, Sourav Poddar 写道:
> On Friday 27 September 2013 08:10 AM, Huang Shijie wrote:
>> 于 2013年09月26日 19:21, Sourav Poddar 写道:
>>> If the pupose of LUT is to just set the dummy cycles, and vf610-twr
>>> hardware state machine does not have have any other dependency
>>> on LUT, this patch should work.
>> Hi Sourav & David:
>>
>>    The key issue about the vf610-twr is that:
>>    [0] Use the LUT makes the Quadspi driver more efficiency.
>>    [1] the vf610-twr needs to know the SPI NOR commands for Page 
>> Program.
>>        Why? because the driver can not change the size of 
>> write-buffer from 256bytes to the 64byte(TXFIFO SIZE).
> Not clear about this. But, you will anyway know what you are using 
> from the m25p80 side rite?

  The TX FIFO is 64 bytes in the Vybrid, but the Page Program may writes 
265 bytes per time.

  If the TX FIFO is smaller then the size of Page Program, we have to 
wait until the Write(64bytes) is finished.
  If we do not wait, the write will not finished.



>>    [2] the dummy and other things.
>>
> Dummy stuffs can be handled from m25p80 side rite? fast read dummy 
> cycle support is already there. While,
> $subject patch adds it for quad read.
The m25p80 can only handle the 8bit dummy now, such as fast read and 
QOR(0x6b).

But it can not handle the QIOR (0XEB, may needs 4bit dummy), and can not 
handle the DDR QIOR(0XED, may
needs 6bit dummy).

thanks
Huang Shijie