[U-Boot] [PATCH V6] sf: Turn SPI flash chip into 3-Byte address mode

[Stefan Roese <sr@denx.de>]

On 13.08.2015 12:50, Hou Zhiqiang wrote:
>> -----Original Message-----
>> From: Siva Durga Prasad Paladugu [mailto:siva.durga.paladugu at xilinx.com]
>> Sent: 2015?8?13? 17:18
>> To: Hou Zhiqiang-B48286; u-boot at lists.denx.de; jteki at openedev.com
>> Cc: Sun York-R58495; Hu Mingkai-B21284; nofooter
>> Subject: RE: [PATCH V6] sf: Turn SPI flash chip into 3-Byte address mode
>>
>> Hi Zhejiang/Jagan,
>>
>> I think it would be good to extend this further to support 4-byte
>> addressing in u-boot also.
>> This would be based on the driver, We can get the data that whether the
>> controller supports 4-byte or not from the driver level(through slave
>> struct) and enable 4 byte addressing here based on that.
>>
>
> That is a long way, and I don't think it is necessary for U-Boot. The U-Boot
> work well using BAR to address more than 16MiB flash.
> This patch focus on the address mode issue when warm boot up base on the BAR
> address mode.

Please correct me if I'm wrong, but AFAIU this BAR thing 
(CONFIG_SPI_FLASH_BAR) doesn't support to address e.g. a 64MiB SPI flash 
contiguously. Only 16MiB areas. So for example its not possible to put 
UBI/UBIFS in such a big partition.

I have to support Siva here. We really should try to support this 4-byte 
mode correctly. This can't be too hard.

Thanks,
Stefan