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

[S Durga Prasad Paladugu]

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/3b5394a3ccffbfa1d1d448d4874285
> 3a862822c4
>
> 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.

Thanks,
Siva


> --
> Jagan.
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