[U-Boot] [UBOOT PATCH 1/2] spi: zynqmp_qspi: Add support for ZynqMP qspi driver

[Jagan Teki]

On Tue, Oct 31, 2017 at 6:33 PM, Siva Durga Prasad Paladugu
<sivadur at xilinx.com> wrote:
> Hi Jagan,
>
>> -----Original Message-----
>> From: Jagan Teki [mailto:jagannadh.teki at gmail.com]
>> Sent: Tuesday, October 31, 2017 3:01 PM
>> To: Siva Durga Prasad Paladugu <sivadur at xilinx.com>
>> Cc: u-boot at lists.denx.de; Liam Beguin <liambeguin at gmail.com>
>> Subject: Re: [UBOOT PATCH 1/2] spi: zynqmp_qspi: Add support for
>> ZynqMP qspi driver
>>
>> On Tue, Oct 31, 2017 at 2:50 PM, Siva Durga Prasad Paladugu
>> <sivadur at xilinx.com> wrote:
>> > Hi Jagan,
>> >
>> >> -----Original Message-----
>> >> From: Jagan Teki [mailto:jagannadh.teki at gmail.com]
>> >> Sent: Tuesday, October 31, 2017 2:40 PM
>> >> To: Siva Durga Prasad Paladugu <sivadur at xilinx.com>
>> >> Cc: u-boot at lists.denx.de; Liam Beguin <liambeguin at gmail.com>; Siva
>> >> Durga Prasad Paladugu <sivadur at xilinx.com>
>> >> Subject: Re: [UBOOT PATCH 1/2] spi: zynqmp_qspi: Add support for
>> >> ZynqMP qspi driver
>> >>
>> >> On Tue, Oct 24, 2017 at 3:33 PM, Siva Durga Prasad Paladugu
>> >> <siva.durga.paladugu at xilinx.com> wrote:
>> >> > This patch adds qspi driver support for ZynqMP SoC. This driver is
>> >> > responsible for communicating with qspi flash devices.
>> >>
>> >> Legacy question, what is your approach for dual memory setup? Did you
>> >> write another flash driver?
>> > No
>> >
>> >>
>> >> I see this driver use dual flash slave 'option' which doesn't live on
>> >> spi side anymore. better to have a discussion on approach and will
>> review further.
>> >
>> > I can see that spi_flash.c(driver/mtd/spi/spi_flash.c) has the option for
>> dual flash under CONFIG_SF_DUAL_FLASH.
>> > I thought of using the same. Isn't it takes care of dual flash case?
>> > Please let me know if you any further thoughts on how it has to be
>> handled.
>>
>> Dual flash case should take for generic spi drivers, if you strictly want your
>> controller to handle flash device rather !flashes then we need to write the
>> driver at flash side. ie why I asked as first question.
>
> Does this mean that drivers that are present in drivers/spi/ should work for both flashes and !flashes. And the
> drivers that only targets flash devices should be in different place and doesn’t use Dual flash functionality under
> CONFIG_SF_DUAL_FLASH? Or it can still use this.

Sorry, you understand it reverse or may be I'm not clear.

drivers at drivers/spi can handle only generic slaves which includes
spi-flash and some spi-flash(spi-nor) controllers which only deals
with spi-flash slaves which can be part of drivers/mtd/spi. Since your
driver is categorized as spi-nor controller(in above notes from you)
it's better to write driver at drivers/mtd/spi side.

Hope it clear.

thanks!
-- 
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.