Re: [PATCH 0/2] rewrite mtk-quadspi spi-nor driver with spi-mem

[Rob Herring]

On Thu, Feb 20, 2020 at 07:58:06AM +0800, Chuanhong Guo wrote:
> Hi!
> 
> On Tue, Feb 18, 2020 at 8:55 PM Mark Brown <broonie@xxxxxxxxxx> wrote:
> > This is an ABI break so you shouldn't be doing this, if the existing
> > binding works it should continue to work.
> 
> The missing spi-max-frequency is the only part preventing old
> device tree to work with this driver.
> If the goal is to make existing dt binding work, I could patch dt using
> of_add_property in v2. I saw similar device tree patching for legacy
> bindings in pinctrl-single driver.

You should should really only need 'spi-max-frequency' if the max freq 
is less than the minimum of the host and device max freq.

Rob