[U-Boot] [PATCH 0/2] Disable hybrid mode for SPANSION S25FS-S family

[Jagan Teki]

On Mon, Oct 30, 2017 at 5:23 PM, Rajat Srivastava
<rajat.srivastava at nxp.com> wrote:
>> On Mon, Oct 30, 2017 at 11:52 AM, Jagan Teki <jagannadh.teki at gmail.com>
>> wrote:
>> > On Mon, Oct 16, 2017 at 12:54 PM, Rajat Srivastava
>> > <rajat.srivastava at nxp.com> wrote:
>> >> The S25FS-S family physical sectors may be configured as a hybrid
>> >> combination of eight 4-kB parameter sectors at the top or bottom of
>> >> the address space with all but one of the remaining sectors being
>> >> uniform size. The default status of the flash is the hybrid
>> >> architecture.
>> >>
>> >> Since the parameter sectors and the uniform sectors have different
>> >> erase commands, it is a problem to implement erase functionality for
>> >> hybrid mode in current U-boot code. Also, enabling hybrid mode
>> >> doesn't provide any significant benefit.
>> >
>> > I think I've asked this question before, keeping the state of the
>> > flash remains same. Can't erase parameter and uniform sectors
>> > individually during operations like
>> > - parameter sectors with erase commands (20h or 21h)
>> > - uniform sectors with erase commands (D8h or DCh)
>>
>> I understand that even we can do parameter and uniform sectors individually
>> with the help of offsets we still have 224. Any idea why we need hybrid mode
>> with this off 244 sector size? if require we can even write cypress on this case.
>>
> Hi Jagan
>
> I am not aware of usage of the remaining 244 sector area. We will discuss this with Cypress.
>
> Moreover, do you have any idea where we apply offset based checks in code? And if we do apply checks, will that look good with current Uboot code?
> I think no one is going to use hybrid mode and even if someone wants to, they can modify the code.

We can change the erase opcode based on the offsets in erase ops,
since if we disable hybrid now, if someone want to re-enable for
another reason (say some kind of protection PB, not sure) will end-up
conflict. Better we can ask Cypress about this and mean while we can
post this change on spi-nor Linux for further discussion.

thanks!
-- 
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.