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

[Jagan Teki]

Hi Tom,

On Tue, Mar 5, 2013 at 11:15 PM, Tom Rini <trini at ti.com> wrote:
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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.

Okay.. what I understand is -
Currently, all the flash supported commands are provided to user as
choice. what what i suppose to implement.
He needs to choose the best option based on what the controller
and chip connected supports.
I guess your idea is to dynamically perform the fastest read/write
command based
on fastest command supported by controller and chip. I don't know how
to support this.

Thanks,
Jagan.

>
> - --
> Tom
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