Re: [PATCH V10 2/2] mtd: spi-nor: Add driver for Cadence Quad SPI Flash Controller.

R, Vignesh
2016-04-14T16:41:39Z

On 04/13/2016 08:36 PM, Marek Vasut wrote:
> On 04/07/2016 06:55 AM, Vignesh R wrote:
>>
>>
>> On 04/07/2016 01:00 AM, Marek Vasut wrote:
>>> On 04/06/2016 06:55 PM, R, Vignesh wrote:
>>>> Hi Marek,
>>>
>>> Hi!
>>>
>>>> I encountered a issue with this driver while testing.
>>>
>>> Try with the attached patches, I am planning to use them for V11
>>> submission. I think you're hitting the problem with missing buslock.
>>>
>>
>> Thanks for the patches.
>> But I am pretty sure that's not the problem at my end, because I have
>> only one flash device on QSPI bus.
>>
>> The problem is cqspi_switch_cs() is called only once ie when JEDEC ID is
>> being read(during autodetect of chip), but at that instance,
>> nor->page_size and nor->mtd.erasesize are not yet initialized (They are
>> initialized only after JEDEC ID is looked up in the table and page_size
>> and erasesize are known).
>> Therefore if nor->page_size is printed during cqspi_switch_cs() then its
>> zero. But nor->page_size reports 256 when printed in cqspi_flash_setup()
>> after spi_nor_scan(). Therefore CQSPI_REG_SIZE register has to be
>> configured only after spi_nor struct is fully populated (i.e after
>> spi_nor_scan() has recognized the slave after JEDEC ID read).
>
> Got it and I have a patch for this. Nice find, thanks! It gave me 60%
> read performance boost on my machine :-)
>

Ah, hope I will see similar improvement at my end :)

> I am now caching the page_size, erasesize, addr_width values, so I can
> avoid reconfiguring the controller if there is no need for it, but
> reconfigure it if there is a need. The patch is attached, but it's quite
> big, so I also pushed a git branch with this driver for your convenience
> (based on linux-next, expect rebases):
>
> https://git.kernel.org/cgit/linux/kernel/git/marex/linux-2.6.git/log/?h=next/cadence-qspi
>

Ok, I will test this on my board sometime soon, thanks.

--
Regards
Vignesh