Re: [PATCH 03/16] dt-bindings: spi: Add spi peripheral specific property

[William Zhang]

Hi Mark,

On 01/09/2023 11:19 AM, Mark Brown wrote:
> On Mon, Jan 09, 2023 at 12:06:13AM -0800, William Zhang wrote:
> > > On Fri, Jan 6, 2023 at 9:27 PM William Zhang <william.zhang@xxxxxxxxxxxx> wrote:
>
> > > Keeping the clock on or not would affect all devices unless you have a
> > > per device clock you can gate, so making this a per device flag
> > > doesn't make sense.
>
> > This applies only to each chip select. There is only one device under each
> > chip select.  So won't impact any other devices under other cs.
>
> I don't understand how this would work - usually a SPI controller has a
> single set of clock, MOSI and MISO lines with the only per device thing
> being the chip select.  If the clock line is used by all devices then it
> must be kept on for all of them if it's to be kept on for one of them.

This setting is set per spi message for particular chip select of the 
device when starting the message through bcm63xx_hsspi_set_clk function 
and restore to default(clock gating) when message is done through 
bcm63xx_hsspi_restore_clk_gate.

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