Re: [PATCH 4/4] gpio: 74x164: Add latch GPIO support

[J. Neuschäfer <j.ne@xxxxxxxxxx>]

On Fri, Dec 13, 2024 at 06:32:50PM +0100, J. Neuschäfer via B4 Relay wrote:
> From: "J. Neuschäfer" <j.ne@xxxxxxxxxx>
> 
> The Fairchild MM74HC595 and other compatible parts have a latch clock
> input (also known as storage register clock input), which must be
> clocked once in order to apply any value that was serially shifted in.
> 
> This patch adds driver support for using a GPIO that connects to the
> latch clock.
> 
> Signed-off-by: J. Neuschäfer <j.ne@xxxxxxxxxx>

I just noticed that this feature is unnecessary for my use-case:
The 74HC595 doesn't have a chip-select input, but if the rising-edge
triggered latch clock input is reinterpreted as an active-low chip
select, it does the right thing.

                     _   _       _   _
 shift clock    ____| |_| |_..._| |_| |_________

 latch clock                           * trigger
                ___                     ________
 chip select#      |___________________|



 -- jn