Re: [PATCH kvm-unit-tests 10/17] pci: provide pci_set_master()

[Peter Xu <peterx@redhat.com>]

On Fri, Nov 04, 2016 at 06:04:56PM +0100, Andrew Jones wrote:
> On Wed, Oct 26, 2016 at 03:47:13PM +0800, Peter Xu wrote:
> > We need to call this whenever we want to do DMA with a device.
> > 
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >  lib/pci.c | 7 +++++++
> >  lib/pci.h | 1 +
> >  2 files changed, 8 insertions(+)
> > 
> > diff --git a/lib/pci.c b/lib/pci.c
> > index 95a6581..1495f61 100644
> > --- a/lib/pci.c
> > +++ b/lib/pci.c
> > @@ -7,6 +7,13 @@
> >  #include "pci.h"
> >  #include "asm/pci.h"
> >  
> > +void pci_set_master(struct pci_dev *dev, int master)
> 
> Why take pci_dev instead of just the devid/bdf here?
> What is the 'master' argument (which is unused and at least
> needs an __unused to compile) here for?

I think both works for me here, but when this happens, IMHO pci_dev
struct is prefered, since as long as the caller has one *dev pointer
(I think if we introduce pci_dev, people should always keep one object
for each PCI device they manipulate in kvm-unit-tests), I would just
let people to pass in "dev" rather than "dev->pci_bdf", since it's
shorter for typing, and also it avoids referencing internal fields.

Regarding to the "master" variable... Oops, I just missed that. What I
want to do is:

	if (master)
		val |= PCI_COMMAND_MASTER;
	else
		val &= ~PCI_COMMAND_MASTER;

Thanks for pointing out. Will fix.

-- peterx