Dummy Cycles for FAST_READ_QUAD_IO_CMD vary between revisions

[Dicklessgreat]

Issue Description

I have encountered an issue with the dummy cycles required for the FAST_READ_QUAD_IO_CMD on different board revisions.

Background

This issue arises from discussions in [#5] and [#4].

Observations

• I have a rev.5 (WM8731) board.
• @kalkyl has a rev.7 (PCM3060) board.
• Both boards use the same flash memory (IS25LP064).

Problem

Despite using the same flash memory, the required dummy cycles for the FAST_READ_QUAD_IO_CMD differ between the two board revisions:

• My rev.5 board requires 8 dummy cycles.
• @kalkyl's rev.7 board requires 6 dummy cycles.

Request

Could someone help investigate why these differences occur and suggest a solution or workaround?