linux-kernel - Re: [PATCH] spi: Setup the master controller driver before setting the chipselect

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Date:	Fri, 16 Oct 2015 15:43:05 +0100
From:	Mark Brown <broonie@...nel.org>
To:	"Franklin S Cooper Jr." <fcooper@...com>
Cc:	linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
	nsekhar@...com, ssantosh@...nel.org, iivanov@...sol.com,
	m-karicheri2@...com, iivanov.xz@...il.com,
	andy.shevchenko@...il.com, jarkko.nikula@...ux.intel.com,
	hkallweit1@...il.com
Subject: Re: [PATCH] spi: Setup the master controller driver before setting
 the chipselect

On Fri, Oct 16, 2015 at 09:27:50AM -0500, Franklin S Cooper Jr. wrote:

> Makes sense. How about something like this?

> SPI controllers may need to be properly setup before chip selects
> can be used. Therefore, wait until the spi controller has a chance
> to perform their setup procedure before trying to use the chip
> select.

Yes, that's a lot better - there's also the fact that if we assert chip
select before we've got the pins in a good state we may cause the device
to see signals that confuse it as we change.

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