[U-Boot] [PATCH v2 2/2] mtd: add altera quadspi driver

Jagan Teki
2015-11-06T08:11:20Z

Hi Marek,

On 5 November 2015 at 21:21, Marek Vasut <marex@denx.de> wrote:
> On Thursday, November 05, 2015 at 03:57:01 PM, Jagan Teki wrote:
>> Hi Thomas,
>>
>> On 5 November 2015 at 20:15, Thomas Chou <thomas@wytron.com.tw> wrote:
>> > Hi Jagan,
>> >
>> > On 2015?11?05? 22:25, Jagan Teki wrote:
>> >> On 5 November 2015 at 14:17, Thomas Chou <thomas@wytron.com.tw> wrote:
>> >>> Add Altera Generic Quad SPI Controller support. The controller
>> >>> converts SPI NOR flash to parallel flash interface. So it is
>> >>> not like other SPI flash, but rather like CFI flash.
>> >>
>> >> Can you wait till spi-nor ready? it doesn't make sense to have Serial
>> >> NOR to created as parallel NOR.
>> >
>> > The altera quad spi core is very special that the hardware handle the
>> > spi-nor protocol. The core is designed to replace the CFI flash
>> > interface. So there is nothing to do with SPI from the parallel flash
>> > interface. It is memory mapped. There is no SPI interface. There is
>> > nothing related to SPI programming. So please don't worry about the
>> > progress on spi-nor. The core should belong to parallel flash, but not
>> > serial flash.
>>
>> Agreed that this is not doing any generic spi things, but it's a
>> spi-nor controller all spi-nor controller should be part of spi-nor
>> subsystem Linux agreed and have a framework for that.
>
> The underlying technology is not exposed to the programmer, so this argument
> is moot. The behavior of this device is closer to CFI flash.
>
>> drivers/mtd/spi-nor/fsl-quadspi.c
>> drivers/mtd/spi-nor/nxp-spifi.c
>>
>> all these are spi-nor controller which doesn't do any generic spi
>> things but should be in spi-nor subsystem. Even Marek send altera_qspi
>> as spi-nor controller [1]
>
> This is because that thing communicates like a SPI controller.

OK, the driver you sent to Linux is not same as this - means not same
controller?

>
>> Since I'm working on similar spi-nor subsystem what Linux have +
>> driver model little worried about this because once we have spi-nor
>> again it should be a re-work.
>
> Your work and this driver are orthogonal things.

OK, let's park my work a side - do you agree with me like this driver
should be part of spi-nor?

>
>> [1] http://lists.infradead.org/pipermail/linux-mtd/2015-April/058650.html

thanks!
--
Jagan | openedev.