netdev - RE: [PATCH] net: can: Remodel FlexCAN register read/write APIs for BE instances

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Date:	Wed, 25 Jun 2014 09:55:10 +0000
From:	"bhupesh.sharma@...escale.com" <bhupesh.sharma@...escale.com>
To:	David Laight <David.Laight@...LAB.COM>,
	"mkl@...gutronix.de" <mkl@...gutronix.de>,
	"linux-can@...r.kernel.org" <linux-can@...r.kernel.org>
CC:	"wg@...ndegger.com" <wg@...ndegger.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH] net: can: Remodel FlexCAN register read/write APIs for BE
 instances

> -----Original Message-----
> From: David Laight [mailto:David.Laight@...LAB.COM]
> Sent: Wednesday, June 25, 2014 2:28 PM
> To: Sharma Bhupesh-B45370; mkl@...gutronix.de; linux-can@...r.kernel.org
> Cc: wg@...ndegger.com; netdev@...r.kernel.org
> Subject: RE: [PATCH] net: can: Remodel FlexCAN register read/write APIs
> for BE instances
> 
> From: Bhupesh Sharma
> > The FlexCAN IP on certain SoCs like (Freescale's LS1021A) is modelled
> > in a big-endian fashion, i.e. the registers and the message buffers
> > are organized in a BE way.
> >
> > More details about the LS1021A SoC can be seen here:
> > http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=LS1021A
> > &nodeId=018rH325E4017B#
> >
> > This patch ensures that the register read/write APIs are remodelled to
> > address such cases, while ensuring that existing platforms (where the
> > FlexCAN IP was modelled in LE way) do not break.
> ...
> Munged to the new code....
> > +static inline u32 flexcan_read(const struct flexcan_priv *priv,
> > +			       void __iomem *addr)
> >  {
> > +	if (priv->devtype_data->module_is_big_endian)
> > +		return ioread32be(addr);
> > +	else
> > +		return ioread32(addr);
> >  }
> >
> > +static inline void flexcan_write(const struct flexcan_priv *priv,
> > +				 u32 val, void __iomem *addr)
> >  {
> > +	if (priv->devtype_data->module_is_big_endian)
> > +		iowrite32be(val, addr);
> > +	else
> > +		iowrite32(val, addr);
> >  }
> 
> Hmmm....
> If performance ever matters that is horrid.
> Probably to the point where making the functions 'inline' is just code
> bloat.
> 

Got the point. See my reply already sent to Marc's review comments.

Regards,
Bhupesh
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