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

Marek Vasut marex at denx.de
Wed Apr 13 08:06:52 PDT 2016


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 :-)

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

-- 
Best regards,
Marek Vasut
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