linux-kernel - Re: [PATCH 2/2] spi: omap2-mcspi: Add support for MULTI-mode

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Message-ID: <ZcIQVKibMmGegw+j@finisterre.sirena.org.uk>
Date: Tue, 6 Feb 2024 10:56:20 +0000
From: Mark Brown <broonie@...nel.org>
To: Louis Chauvet <louis.chauvet@...tlin.com>
Cc: linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
	thomas.petazzoni@...tlin.com,
	Miquel Raynal <miquel.raynal@...tlin.com>, yen-mei.goh@...sight.com,
	koon-kee.lie@...sight.com
Subject: Re: [PATCH 2/2] spi: omap2-mcspi: Add support for MULTI-mode

On Tue, Feb 06, 2024 at 11:00:50AM +0100, Louis Chauvet wrote:

> Introduce support for MULTI-mode in the OMAP2 MCSPI driver. Currently, the
> driver always uses SINGLE mode to handle the chip select (CS). With this
> enhancement, MULTI-mode is enabled for specific messages, allowing for a
> shorter delay between CS enable and the message (some FPGA devices are
> sensitive to this delay).

I have no idea based on this commit message what either of these modes
is or how this shorter delay would be achieved, these terms are specific
to the OMAP hardware AFAICT.  Please clarify this, it's hard to follow
what the change does.  It looks like this is just a CS per word thing?

Note that you may not have to tell the hardware the same word length as
the transfer specifies, so long as the wire result is the same it
doesn't matter.

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