Re: [PATCH 2/6] device/pci: add cmdmem cap to pci_dev

[Dave Jiang]

On 3/31/2020 10:24 AM, Greg KH wrote:
> On Tue, Mar 31, 2020 at 10:07:07AM -0700, Dave Jiang wrote:
> > On 3/31/2020 3:04 AM, Greg KH wrote:
> > > On Mon, Mar 30, 2020 at 02:27:00PM -0700, Dave Jiang wrote:
> > > > Since the current accelerator devices do not have standard PCIe capability
> > > > enumeration for accepting ENQCMDS yet, for now an attribute of pdev->cmdmem has
> > > > been added to struct pci_dev.  Currently a PCI quirk must be used for the
> > > > devices that have such cap until the PCI cap is standardized. Add a helper
> > > > function to provide the check if a device supports the cmdmem capability.
> > > >
> > > > Such capability is expected to be added to PCIe device cap enumeration in
> > > > the future.
> > > >
> > > > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
> > > > ---
> > > >    drivers/base/core.c    |   13 +++++++++++++
> > > >    include/linux/device.h |    2 ++
> > > >    include/linux/pci.h    |    1 +
> > > >    3 files changed, 16 insertions(+)
> > > >
> > > > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > > > index dbb0f9130f42..cd9f5b040ed4 100644
> > > > --- a/drivers/base/core.c
> > > > +++ b/drivers/base/core.c
> > > > @@ -27,6 +27,7 @@
> > > >    #include <linux/netdevice.h>
> > > >    #include <linux/sched/signal.h>
> > > >    #include <linux/sysfs.h>
> > > > +#include <linux/pci.h>
> > > >    #include "base.h"
> > > >    #include "power/power.h"
> > > > @@ -3790,3 +3791,15 @@ int device_match_any(struct device *dev, const void *unused)
> > > >    	return 1;
> > > >    }
> > > >    EXPORT_SYMBOL_GPL(device_match_any);
> > > > +
> > > > +bool device_supports_cmdmem(struct device *dev)
> > > > +{
> > > > +	struct pci_dev *pdev;
> > > > +
> > > > +	if (!dev_is_pci(dev))
> > > > +		return false;
> > > > +
> > > > +	pdev = to_pci_dev(dev);
> > > > +	return pdev->cmdmem;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(device_supports_cmdmem);
> > > Why would a pci-specific function like this be ok to have in the driver
> > > core?  Please keep it in the pci core code instead.
> > The original thought was to introduce a new arch level memory mapping
> > semantic.
> Please do not.  Also, that's not what you are doing here from what I can
> tell.
>
> > If you feel this should be PCI exclusive, should we make the ioremap
> > routines for this memory type pci specific as well?
> Why wouldn't it be?  Is this needed anywhere else?

Ok I'll make this pci specific.


> thanks,
>
> greg k-h