On Mon, Feb 15, 2010 at 10:51:32PM +0100, Wolfgang Grandegger wrote:
> Ira Snyder wrote:
> > On Mon, 15 Feb 2010 09:54:22 +0100
> > Kurt Van Dijck <[email protected]> wrote:
> > 
> >> On Fri, Feb 12, 2010 at 03:50:53PM -0800, Ira W. Snyder wrote:
> >>> The Janz ICAN3 is a MODULbus daughterboard which fits on the Janz CMOD-IO
> >>> PCI carrier board. It is an intelligent CAN controller, with a
> >>> microcontroller and associated firmware.
> >>>
> >>> Signed-off-by: Ira W. Snyder <[email protected]>
> >>> ---
> >>>
> >> [...]
> >>> +/* Maximum number of buffers on a CMOD-IO carrier board */
> >>> +#define JANZ_MAX_MODULES 4
> >>> +
> >>> +struct janz_device {
> >>> + struct device *dev;
> >>> + struct pci_dev *pdev;
> >> is dev == &pdev->dev?
> > 
> > Yep. Convenience for printing stuff, so we have:
> > dev_dbg(priv->dev, "msg\n");
> > 
> > Instead of:
> > dev_dbg(&priv->pdev->dev, "msg\n");
> > 
> > It really helps on lines that are close to the 80 character limit. If
> > you're worried about speed, the PCI accesses are going to hurt much
> > more than a pointer dereference.
> 
> What does hurt is the extra space for the variable. You can always declare:
> 
>   struct device *dev = &priv->pdev->dev;
or even :
#define DEV(x) (&priv->pdev->dev)

and 

dev_dbg(DEV(priv), ....)

> 
> at the beginning of the functions if you use it often or want to shorten
> lines. This costs nothing as the compiler will optimze anyhow.
> 
> Wolfgang.
> 
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