netdev - Re: [net-next PATCH 1/1] drivers: net: cpsw: Add support for new CPSW IP version

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Date:	Wed, 31 Jul 2013 21:45:25 +0300
From:	Felipe Balbi <balbi@...com>
To:	Richard Cochran <richardcochran@...il.com>
CC:	Felipe Balbi <balbi@...com>, Mugunthan V N <mugunthanvnm@...com>,
	<netdev@...r.kernel.org>, <davem@...emloft.net>,
	<linux-omap@...r.kernel.org>
Subject: Re: [net-next PATCH 1/1] drivers: net: cpsw: Add support for new
 CPSW IP version

Hi,

On Wed, Jul 31, 2013 at 06:38:46PM +0200, Richard Cochran wrote:
> On Wed, Jul 31, 2013 at 06:28:27PM +0300, Felipe Balbi wrote:
> > On Wed, Jul 31, 2013 at 04:49:59PM +0200, Richard Cochran wrote:
> > > On Wed, Jul 31, 2013 at 05:42:26PM +0530, Mugunthan V N wrote:
> > > > The new IP version has a minor changes and the offsets are same as the previous
> > > > version, so instead of adding CPSW version number in the driver, make the driver
> > > > to fall through to the latest versions so that the new version of CPSW which has
> > > > the same register offsets will work directly without patching the driver.
> > > 
> > > This doesn't make any sense to me. Why not just add the new version
> > > number?
> > > 
> > > None of the hunks in your patch are on performance sensitive paths, so
> > > I really can't see any point in removing the error checking.
> > 
> > well, if a new revision of the IP comes, the driver at least has some
> > chance to work without having to be modified. If it turns out that there
> > are really different features, then we patch a new version, otherwise we
> > should just assume highest known version and try it out.
> 
> And if the driver reads junk from some random address due to
> bootloader/DT/multikernel madness, it will happily peek and poke
> around instead of rejecting the wrong version number.

that'd be a bug in the DT anyway, why should the driver have to cope
with broken data ?

-- 
balbi

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