linux-kernel - Re: [PATCH 08/20] Staging: ipack: Switch to 8MHz operation before reading ID.

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Message-ID: <1347374377.4539.115.camel@fourier.local.igalia.com>
Date:	Tue, 11 Sep 2012 16:39:37 +0200
From:	Samuel Iglesias Gonsálvez 
	<siglesias@...lia.com>
To:	Jens Taprogge <jens.taprogge@...rogge.org>
Cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	industrypack-devel@...ts.sourceforge.net
Subject: Re: [PATCH 08/20] Staging: ipack: Switch to 8MHz operation before
 reading ID.

On Tue, 2012-09-11 at 13:39 +0200, Jens Taprogge wrote:
> On Tue, Sep 11, 2012 at 01:31:06PM +0200, Samuel Iglesias Gonsálvez wrote:
> > On Tue, 2012-09-11 at 11:48 +0300, Dan Carpenter wrote:
> > > On Mon, Sep 10, 2012 at 10:51:46AM +0200, Samuel Iglesias Gonsálvez wrote:
> > > > From: Jens Taprogge <jens.taprogge@...rogge.org>
> > > > 
> > > > Reading the ID space at 8 MHz is always supported.  Most carriers will
> > > > boot up in 8MHz mode.  Still, play it safe and ensure we are operating at
> > > > 8Mhz.
> > > > 
> > > > Signed-off-by: Jens Taprogge <jens.taprogge@...rogge.org>
> > > > Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@...lia.com>
> > > > ---
> > > >  drivers/staging/ipack/ipack.c |   11 ++++++++---
> > > >  1 file changed, 8 insertions(+), 3 deletions(-)
> > > > 
> > > > diff --git a/drivers/staging/ipack/ipack.c b/drivers/staging/ipack/ipack.c
> > > > index 4f3c945..95f56b8 100644
> > > > --- a/drivers/staging/ipack/ipack.c
> > > > +++ b/drivers/staging/ipack/ipack.c
> > > > @@ -376,6 +376,9 @@ struct ipack_device *ipack_device_register(struct ipack_bus_device *bus,
> > > >  	dev_set_name(&dev->dev,
> > > >  		     "ipack-dev.%u.%u", dev->bus_nr, dev->slot);
> > > >  
> > > > +	if (bus->ops->set_clockrate(dev, 8))
> > > > +		dev_warn(&dev->dev, "failed to switch to 8 MHz operation for reading of device ID.\n");
> > > > +
> > > >  	ret = ipack_device_read_id(dev);
> > > >  	if (ret < 0) {
> > > >  		dev_err(&dev->dev, "error reading device id section.\n");
> > > > @@ -384,9 +387,11 @@ struct ipack_device *ipack_device_register(struct ipack_bus_device *bus,
> > > >  	}
> > > >  
> > > >  	/* if the device supports 32 MHz operation, use it. */
> > > > -	ret = bus->ops->set_clockrate(dev, dev->speed_32mhz ? 32 : 8);
> > > > -	if (ret < 0)
> > > > -		dev_err(&dev->dev, "failed to switch to 32 MHz operation.\n");
> > > > +	if (dev->speed_32mhz) {
> > > > +		ret = bus->ops->set_clockrate(dev, 32);
> > > > +		if (ret < 0)
> > > > +			dev_err(&dev->dev, "failed to switch to 32 MHz operation.\n");
> > > > +	}
> > > 
> > > Ah.  Well done.  That's what I suggested earlier.  I think you
> > > should get rid of the ->speed_8mhz all together.
> > 
> > I will do it in a follow-up patch. The rest of suggestions have been
> > integrated in the patches. I will submit the patches very soon.
> 
> I have not seen any IPack V2 device yet.  But since the ID space
> provides the 8MHz flag, it might be useful.  On the other hand, we can
> still readd it when we see it.
> 

If we have the flag, we should use it in some point. Not only save it in
the variable speed_8mhz and don't use it at all.

> When you remove the flag, you can perhaps leave a comment in the code so
> that it is easy to re-enable.
> 

OK. I will send a patch in Industry Pack mailing list and we can discuss
there if this is a good solution or not before sending to staging ML.

Thanks,

Sam


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