On Tue, 2010-11-02 at 16:07 +0200, Michael S. Tsirkin wrote:
> On Tue, Nov 02, 2010 at 08:00:38AM -0600, Alex Williamson wrote:
> > On Tue, 2010-11-02 at 11:25 +0200, Michael S. Tsirkin wrote:
> > > On Mon, Nov 01, 2010 at 11:37:53PM -0600, Alex Williamson wrote:
> > > > Avoid needing to get the MSI capability flags every time we need to
> > > > check the capability length. This also makes it accessible outside
> > > > of msi.c, making it easier for users to filter config space writes
> > > > using msi_cap and msi_cap_size.
> > >
> > > I think for this last use-case, we are better off with returning a
> > > boolean from msi_write_config which tells us whether the write is in
> > > range. This has the advantage in that it will also work well for other
> > > capabilities. Or second best, if that is insufficient for some reason,
> > > export an msi_cap_size function.
> >
> > Returning whether the write was in range isn't enough. For device
> > assignment, I need to know whether the capability was enabled or
> > disabled. This currently means checking the enable state before and
> > after calling msi_write_config and doing the appropriate backend setup.
>
> Sounds good. Why does this mean you need the capability size?
> bool was_enabled = msi_enabled(dev);
> msi_write_config(..)
> if (was_enabled != msi_enabled(dev)) {
> }
Because this code makes me sad...
bool msi_was_enabled, msix_was_enabled, msi_is_enabled, msix_is_enabled;
msi_was_enabled = msi_enabled(dev);
msix_was_enabled = msix_enabled(dev);
pci_default_write_config(...
msi_write_config(...
msix_write_config(...
msi_is_enabled = msi_enabled(dev);
msix_is_enabled = msix_enabled(dev);
if (msi_was_enabled && !msi_is_enabled)
disable_msi(...
if (!msi_was_enabled && msi_is_enabled)
enable_msi(...
if (msix_was_enabled && !msix_is_enabled)
disable_msi(...
if (!msix_was_enabled && msix_is_enabled)
enable_msix(...
Confining msi tests to an msi related write and msix tests to an msix
related write makes me slightly happier. I really think we need
callbacks though so common msi/msix code can figure out if we've made a
transition.
Alex
> > I think the only way I could blindly call the msi/x write config
> > routines is if we init the capability with enable/disable callbacks.
> > I'd be ok with an msi_cap_size function if we don't want to go that far
> > too. What do you prefer? Thanks,
