[U-Boot] [PATCH 00/12] cmd_sf: Add support for read and write instructions

[Tom Rini]

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On 03/05/2013 12:21 PM, Jagan Teki wrote:
> Hi Tom,
> 
> On Tue, Mar 5, 2013 at 10:38 PM, Tom Rini <trini at ti.com> wrote: On
> 03/05/2013 12:00 PM, Jagan Teki wrote:
>>>> Hi Tom,
>>>> 
>>>> On Tue, Mar 5, 2013 at 2:38 AM, Tom Rini <trini at ti.com>
>>>> wrote:
>>>>> On Sat, Mar 02, 2013 at 01:59:38PM +0530, Jagan Teki
>>>>> wrote:
>>>>> 
>>>>> [snip]
>>>>>> Since these changes I have sent long back, I am just 
>>>>>> re-modified the framework to add new features at the same
>>>>>> time with backward comparability for current commands.
>>>>>> 
>>>>>> Current command setup: sf write sf read sf update
>>>>>> 
>>>>>> Changed command set: [no changes in the argument count]
>>>>>> sf write     ---  current command sf write.pp --  same as
>>>>>> sf write sf write.qp -- quad program
>>>>>> 
>>>>>> sf read   -- current read sf read.af --- array flast
>>>>>> read, same as sf read sf read.as -- array slow read sf
>>>>>> read.do --- dual out sf read.qo -- quad out sf read.dio
>>>>>> -- dual io sf read.qio -- quad io
>>>>>> 
>>>>>> sf update  -- current update sf update.pp.af -- write
>>>>>> page program, read array fast, same as sf update sf
>>>>>> update.pp.as - write page program, read array slow sf
>>>>>> update.pp.do - write page program, read dual out sf
>>>>>> update.pp.qo - write page program, read quad out sf
>>>>>> update.pp.dio - write page program, read dual io sf
>>>>>> update.pp.qio - write page program, read quad io sf
>>>>>> update.qp.af - write quad program, read array fast sf 
>>>>>> update.qp.as - write quad program, read array slow sf 
>>>>>> update.qp.do - write quad program, read dual out sf 
>>>>>> update.qp.qo - write quad program, read quad out sf 
>>>>>> update.qp.dio - write quad program, read dual io sf 
>>>>>> update.qp.qio - write quad program, read quad io
>>>>>> 
>>>>>> Though it seems to be lengthy, but may useful with lot
>>>>>> of combinations from user. My intention is to use the
>>>>>> existing argument count with changes in the command set.
>>>>> 
>>>>> Are there cases where for the current device we're
>>>>> operating on that can handle more than one of these, aside
>>>>> from fast or slow? And do we really need to offer both fast
>>>>> and slow?
>>>> 
>>>> Yes as per as I know spansion, numonyx and winbond flashes
>>>> are supporting all the operation modes that I listed above.
>>>> 
>>>> These are very generic w.r.t above flashes.or I can say these
>>>> are commonly available modes.
> 
> And when hooked up via whichever SPI controller you have, all of
> those modes are also available and we can't really "guess" about
> using a faster mode?
>> I didn't get you. In general, u-boot should provide all the
>> possible operation modes and the choice should be up to user. 
>> Please elaborate as I seem to be missing something.

Unless I'm missing something (or we're talking about different
things), you have a SPI flash that do quad (or dual) read/write.  But
it also has to be connected to a controller that talks quad (or dual).

So is there any way we can make sf read/write/update be the fastest
supported (and why do we want fast and slow quad programming?) by the
controller and chip?  I can see having to do "sf read.qp.qf ..." and
so forth leading to some less than desired user interaction.

- -- 
Tom
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