Re: [PATCH v3] mtd: spi-nor: fix spansion quad enable

[Marek Vasut <marek.vasut@gmail.com>]

On 11/25/2016 05:01 PM, Esponde, Joel wrote:
>> -----Message d'origine-----
>> De : Marek Vasut [mailto:marek.vasut@gmail.com]
>> Envoyé : vendredi 25 novembre 2016 16:08
>> À : Cyrille Pitchen <cyrille.pitchen@atmel.com>; Esponde, Joel
>> <Joel.Esponde@Honeywell.com>; linux-mtd@lists.infradead.org
>> Objet : Re: [PATCH v3] mtd: spi-nor: fix spansion quad enable
>>
>> On 11/25/2016 03:50 PM, Cyrille Pitchen wrote:
>>> Hi Marek,
>>
>> Hi,
>>
>>> Le 25/11/2016 à 15:17, Marek Vasut a écrit :
>>>> On 11/23/2016 12:47 PM, Joël Esponde wrote:
>>>>> With the S25FL127S nor flash part, each writing to the configuration
>>>>> register takes hundreds of ms. During that  time, no more accesses
>>>>> to the flash should be done (even reads).
>>>>>
>>>>> This commit adds a wait loop after the register writing until the
>>>>> flash finishes its work.
>>>>>
>>>>> This issue could make rootfs mounting fail when the latter was done
>>>>> too much closely to this quad enable bit setting step. And in this
>>>>> case, a driver as UBIFS may try to recover the filesystem and may
>>>>> broke it completely.
>>>>
>>>> Does this apply to all spansion chips or only to selected few ?
>>>>
>>>
>>> I've recently faced the very same issue with Winbond memories, which
>>> use the same procedure as Spansion to set the Quad Enable bit.
>>> More precisely, in my case it was some bare metal (bootloader) code
>>> but the issue was the same, there was no polling of busy bit from the
>>> Status Register after having set the QE bit in the Status Register 2 /
>>> Control Register 1. Then the next SPI command came too early and
>>> failed because the memory was actually still busy.
>>>
>>> I faced this issue with Winbond W25Q256 and W25M512.
>>
>> So we can leave this code as is ?
>>
> 
> 
> Hi,
> 
> I checked these data sheets, and in all of them, Bit 0 of the Status Register stands for WIP (Work in progress).
> 
> S25FL032P	http://www.cypress.com/file/196861/download#G4.1231516
> S25FL064P	http://www.cypress.com/file/196856/download#G3.1231516
> S25FL127S	http://www.cypress.com/file/177961/download#G3.1468489
> S25FL128S,
> S25FL256S	http://www.cypress.com/file/177966/download#G3.1254282
> S25FL512S,
> S70FL01GS	http://www.cypress.com/file/177971/download#G3.1238704
> S25FL129P	http://www.cypress.com/file/197121/download#G4.1231516
> S25FL004K,
> S25FL008K,
> S25FL016K	http://www.mouser.com/ds/2/380/spansion%20inc_s25fl004k-016k_00-329492.pdf#page=16&zoom=auto,61,683
> S25FL128K	http://www.cypress.com/file/228376/download#G4.1299435
> S25FL116K,
> S25FL132K,
> S25FL164K	http://www.cypress.com/file/196886/download#G3.1239521
> S25FL204K	http://www.cypress.com/file/196871/download#G4.1354778
> 
> I was not able to find the data sheets of S25SL parts.
> Based on this old patch provided by an Spansion engineer, it looks like S25SL family never existed:
> https://patchwork.ozlabs.org/patch/59109/

Oh great, thanks a lot for checking :-) So we can leave the code as is.

Regarding the S25SL, I found [1], but that might be a typo.

[1]
http://lxr.free-electrons.com/source/arch/powerpc/boot/dts/mpc8536ds.dts?v=3.0

-- 
Best regards,
Marek Vasut