[U-Boot] [PATCH v3 1/3] spi: spi_flash: Dont set quad enable for micron in all cases

[Jagan Teki]

On Thu, Oct 20, 2016 at 5:08 PM, S Durga Prasad Paladugu
<durgaprasad.psdp at gmail.com> wrote:
> Hi Jagan,
>
> On Wed, Jul 27, 2016 at 3:26 PM, Jagan Teki <jagannadh.teki at gmail.com>
> wrote:
>>
>> On 27 July 2016 at 14:31, Siva Durga Prasad Paladugu
>> <siva.durga.paladugu at xilinx.com> wrote:
>> > Hi Jagan,
>> >
>> >> -----Original Message-----
>> >> From: Jagan Teki [mailto:jagannadh.teki at gmail.com]
>> >> Sent: Wednesday, July 27, 2016 1:24 PM
>> >> To: Siva Durga Prasad Paladugu <sivadur at xilinx.com>
>> >> Cc: u-boot at lists.denx.de; Michal Simek <michals at xilinx.com>; Siva Durga
>> >> Prasad Paladugu <sivadur at xilinx.com>
>> >> Subject: Re: [PATCH v3 1/3] spi: spi_flash: Dont set quad enable for
>> >> micron in all
>> >> cases
>> >>
>> >> On 19 July 2016 at 14:40, Siva Durga Prasad Paladugu
>> >> <siva.durga.paladugu at xilinx.com> wrote:
>> >> > Dont set quad enable for micron devices in all cases Setting the quad
>> >> > enable bit in micron expects all other commands like register reads
>> >> > on
>> >> > quad lines which may not be supported by some controllers. Hence,
>> >> > dont
>> >> > set the quad enable if controller driver sets the no_all_quad.
>> >>
>> >> Sorry, I'm not fond of controller hacks, please try for any other
>> >> solution and
>> >> even planning to remove existing ones.
>> > Definitely there should be a way to mention about controller
>> > capabilities to the
>> > Framework. As of now I can see this is only way. Do you have any other
>> > Suggested way which is already in place.
>> > I can see that Linux mainline has already removed Micron quad enable
>> > functionality with this patch. Probably because of same kind of reason
>> >
>> > https://github.com/torvalds/linux/commit/3b5394a3ccffbfa1d1d448d48742853a862822c4
>>
>> The reason to remov this support from Linux is different than this,
>> and u-boot have support for quad write ie not supported by Linux.
>
>
> We can still have quad write with out quad enable bit set for micron
> as it supports quad page program in extended spi(command on single and data
> on 4 lines).
> The issue for me is when the quad enable bit was set for micron, it expects
> everything on
> four lines even for register reads.

I need to investigate further on this, will update you if I find any.

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