[U-Boot] [PATCH v2 03/12] spi: sf: Support byte program for sst spi flash

[Bin Meng]

Hi Jagan,

On Tue, Dec 9, 2014 at 2:04 AM, Jagan Teki <jagannadh.teki at gmail.com> wrote:
> Hi Bin,
>
> On 1 November 2014 at 14:23, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Currently if SST flash advertises SST_WP flag in the params table
>> the word program command (ADh) with auto address increment will be
>> used for the flash write op. However some SPI controllers do not
>> support the word program command (like the Intel ICH 7), the byte
>> programm command (02h) has to be used.
>>
>> A new TX operation mode SPI_OPM_TX_BP is introduced for such SPI
>> controller to use byte program op for SST flash.
>
> We have SST_WP which is word program - for specific flash's (not for
> controller specific
> at-least from params data)
>
> Which is this SST_BP relies for ? controller or specific flash ?
>

SST_BP is flash specific. In current flash params table, I checked
every flash datasheet and found that when an SST flash supports WP, it
also supports BP. I believe the WP and BP are companion commands. When
an SST flash does not support BP/WP, it supports the page program
(02h) which uses the same command code as BP. And the page program
(02h) is the command selected by U-Boot for SST flashes which do not
have SST_WP flag.

However some controllers do not support WP, so that we need the SST_BP
flag to let U-Boot selects BP for such controllers, which is what my
patch tries to fix.

[snip]

Regards,
Bin