linux-kernel - RE: [PATCH] SPI: Add driver for Cadence SPI controller

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Date:	Tue, 18 Mar 2014 05:22:37 +0000
From:	Harini Katakam <harini.katakam@...inx.com>
To:	Mark Brown <broonie@...nel.org>,
	Josh Cartwright <joshc@...eaurora.org>
CC:	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"pawel.moll@....com" <pawel.moll@....com>,
	"mark.rutland@....com" <mark.rutland@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	"galak@...eaurora.org" <galak@...eaurora.org>,
	"rob@...dley.net" <rob@...dley.net>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
	Michal Simek <michals@...inx.com>
Subject: RE: [PATCH] SPI: Add driver for Cadence SPI controller

Hi Mark,

> -----Original Message-----
> From: Mark Brown [mailto:broonie@...nel.org]
> Sent: Monday, March 17, 2014 11:45 PM
> To: Josh Cartwright
> Cc: Harini Katakam; robh+dt@...nel.org; pawel.moll@....com;
> mark.rutland@....com; ijc+devicetree@...lion.org.uk;
> galak@...eaurora.org; rob@...dley.net; grant.likely@...aro.org;
> devicetree@...r.kernel.org; linux-doc@...r.kernel.org; linux-
> kernel@...r.kernel.org; linux-spi@...r.kernel.org; Michal Simek
> Subject: Re: [PATCH] SPI: Add driver for Cadence SPI controller
> 
> On Mon, Mar 17, 2014 at 12:59:11PM -0500, Josh Cartwright wrote:
> > On Mon, Mar 17, 2014 at 05:30:17PM +0000, Mark Brown wrote:
> > > On Mon, Mar 17, 2014 at 05:35:36PM +0530, Harini Katakam wrote:
> 
> > > > +static int __maybe_unused cdns_spi_suspend(struct device *dev) {
> 
> > > This needs to call spi_master_suspend() as well (and similarly on
> > > resume).
> 
> > I'm not that familiar with the SPI core, but this seems like an
> > inversion.  Is there a reason why the SPI master class doesn't
> > implement
> > suspend/resume() callbacks which handle stopping/starting the queue
> > automatically for all masters?
> 
> This is for users of an optional feature of the infrastructure.  We probably
> should just call it anyway since it does have checks for the feature being
> used (but given all the open coding around this stuff I'd need to verify that
> the class callbacks would reliably get called).
> 
> In any case that's not happening now and the driver as it stands is buggy
> since it's trampling all over the hardware without syncing with anything that
> isn't ongoing.

In case of a suspend, we are stopping an ongoing transfer and disabling the interface.
In case I add clock disable and anything else to unprepared too, it will be a cleaner 
exit but it will still stop the transfer right? What do you suggest?
Should we wait for transfer to complete or a timeout to occur?

Regards,
Harini


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