[U-Boot] [EXT] Re: [PATCH 1/6] spi: fsl_qspi: Fix DDR mode setting for latest iMX platforms

[Stefan Roese]

On 23.10.19 12:34, Schrempf Frieder wrote:

<snip>

>>>>> BTW: Using the "spi-mem" driver version from Ashish with the fix
>>>>> suggested by Frieder to clear the DDR bit in TDH (reset to 00) still
>>>>> works without any problems.
>>>>
>>>> There is some cleanup work that needs to be done (e.g. [1]). After
>>>> that I will send an official patch for the spi-mem driver. Then Ashish
>>>> and you can comment with your test results and change requests.
>>>
>>> Sounds like a good plan. Please keep me on Cc on any of these patches, so
>>> that I don't forget to review and test them. Thanks in advance.
>>
>> Hi Frieder,
>>
>> I see one issue with current SPI-MEM driver getting ported in u-boot, that is: access via md command is not working, in order words direct access to flash memory is no more possible, which was previously possible. Such access is helpful to access memory directly and make user experience similar to parallel NOR.
> 
> Yes, direct memory-mapped access to the whole flash is not possible with
> this driver. Though I don't see any good reason why someone wants to do
> this, when there's a SPI NOR and MTD layer to abstract the flash and
> handle access to it. You can still use sf and/or mtd commands to
> read/write data between flash and RAM.

I agree with Frieder that we don't need this direct memory access via
"md/mm/etc" in U-Boot. Access via the "normal" sf and/or mtd commands
should be enough for SPI NOR.

Thanks,
Stefan