On Sat, Feb 15, 2020 at 02:58:24PM +0800, Chuanhong Guo wrote:

To keep patchset small for easier reviewing, there will be 3 patchsets
including this one.
1. add the new driver, which is this patchset.
2. update existing dts for the new driver:
   spi-max-frequency is missing in current mtk-quadspi binding. Old
   driver parses child node manually so it doesn't need this, but
   new spi-mem driver is probed via spi subsystem which requires the
   presence of spi-max-frequency. Since this doesn't break old driver
   support, I'll send this separately as a standalone patch.

This is an ABI break so you shouldn't be doing this, if the existing
binding works it should continue to work.

3. removing the old driver. I'll create this commit after 1 and 2 are
   applied to avoid possible rebasing due to any changes in the old
   driver.

This isn't great as it means we have a period with two drivers for the
same thing in tree which is at best going to be confusing.  There's no
advantage to splitting this out.