[U-Boot] [RFC 0/5] sf: Update spi-nor framework

[Marek Vasut]

On 12/12/2017 08:37 AM, Jagan Teki wrote:
> On Tue, Dec 12, 2017 at 11:44 AM, Prabhakar Kushwaha
> <prabhakar.kushwaha at nxp.com> wrote:
>> Hi Marek,
>>
>>> -----Original Message-----
>>> From: Marek Vasut [mailto:marek.vasut at gmail.com]
>>> Sent: Monday, December 11, 2017 3:04 PM
>>> To: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>; u-
>>> boot at lists.denx.de
>>> Cc: jagannadh.teki at gmail.com; Poonam Aggrwal
>>> <poonam.aggrwal at nxp.com>; Suresh Gupta <suresh.gupta at nxp.com>;
>>> cyrille.pitchen at atmel.com
>>> Subject: Re: [RFC 0/5] sf: Update spi-nor framework
>>>
>>> On 12/11/2017 06:57 AM, Prabhakar Kushwaha wrote:
>>>> SPI-NOR framework currently supports-
>>>>  - (1-1-1, 1-1-2, 1-1-4) read protocols
>>>>  - read latency(dummy bytes) are hardcoded with the assumption
>>>>  that the flash would support it.
>>>>  - No support of mode bits.
>>>>  - No support of flash size above 128Mib
>>>>
>>>> This patch set add support of 1-2-2, 1-4-4 read protocols.
>>>> It ports Linux commits "mtd: spi-nor: add a stateless method to support
>>>> memory size above 128Mib" and "mtd: spi-nor: parse Serial Flash
>>>> Discoverable Parameters (SFDP) tables". It enables 4byte address opcode
>>>> and run time flash parameters discovery including dummy cycle and mode
>>>> cycle.
>>>>
>>>> Finally it update fsl-quadspi driver to store(set_mode) spi bus mode and
>>>> provision for run-time LUTs creation.
>>>>
>>>> Note: This patch-set is only **compliation** tested. Sending RFC to get
>>>> early feed-back on the approach.
>>>>
>>>> Prabhakar Kushwaha (5):
>>>>   sf: Add support of 1-2-2, 1-4-4 IO READ protocols
>>>>   sf: add method to support memory size above 128Mib
>>>>   sf: parse Serial Flash Discoverable Parameters (SFDP) tables
>>>>   sf: fsl_qspi: Add support of fsl_qspi_set_mode
>>>>   sf: fsl_quadspi: Configue LUT based on padding information
>>>>
>>>>  drivers/mtd/spi/sf_internal.h   | 230 +++++++++++++++-
>>>>  drivers/mtd/spi/spi_flash.c     | 574
>>> +++++++++++++++++++++++++++++++++++++++-
>>>>  drivers/spi/fsl_qspi.c          |  85 +++++-
>>>>  include/spi_flash.h             |   2 +
>>>>  5 files changed, 875 insertions(+), 18 deletions(-)
>>>>
>>>
>>> Could you rather port the entire SPI NOR framework from Linux 4.14 ?
>>> That'd make more sense than porting bits and pieces on top of the
>>> current crappy code IMO.
>>
>> I agree with you. Linux 4.14 SPI NOR framework should be ported.
>> I may not able to do this because of bandwidth and lack of expertise.
>> I will request Jagan (custodian) to look into this.
>>
>> This RFC patch-set can easily be applied to existing and  ported Linux SPI NOR framework when it gets available.
>>
>> For now, I think these patches(the next version) with the existing framework can be reviewed and accepted.
>> Please help to share your views.
>>
>> For next version of this patch set, I will be working on testing  it to enable other flashes.
>> It will also help Jagan during 4.14 porting.
>> Jagan, your views?
> 
> direct-porting from Linux is not so optimal(not well suited for U-Boot
> design) as I've tried before.

Care to elaborate on the technical problems ? I am also CCing the Linux
SPI NOR maintainers, since I believe the Linux SPI NOR framework is far
superior compared to the stuff that's now in U-Boot and sharing the code
as much as possible would only make sense rather than writing our own
barely-maintained and crappy implementation.

> We're working on the dm-driven spi-nor.
> So I will continue to review your patches on current code and will see
> how we can merge the same once dm-spi-nor available.
> 
> Jagan.
> 


-- 
Best regards,
Marek Vasut