Messages in this thread Patch in this message | | | Date | Sat, 9 Jun 2007 00:59:53 -0600 | From | Grant Grundler <> | Subject | Re: [PATCH 1/2] [RFC] PCI: read revision ID by default |
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On Fri, Jun 08, 2007 at 03:46:30PM -0700, Auke Kok wrote: > Currently there are 97 occurrences where drivers need the pci > revision ID. We can do this once for all devices. Even the pci > subsystem needs the revision several times for quirks. The extra > u8 member pads out nicely in the pci_dev struct.
Good idea. I always wondered why we read the invariants so often in the code.
> > Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com> > --- > > drivers/pci/probe.c | 3 +++ > include/linux/pci.h | 1 + > 2 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index e48fcf0..0fdb71d 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -918,6 +918,9 @@ pci_scan_device(struct pci_bus *bus, int devfn) > dev->cfg_size = pci_cfg_space_size(dev); > dev->error_state = pci_channel_io_normal; > > + /* read the PCI revision: 1 byte */ > + pci_read_config_byte(dev, PCI_REVISION_ID, &dev->revision);
probe.c:pci_setup_device() is also reading this byte but discards it: pci_read_config_dword(dev, PCI_CLASS_REVISION, &class); class >>= 8; /* upper 3 bytes */ dev->class = class;
Can you use "class & 0xff"? Or is pci_setup_device() too late? Or can you read the whole 32-bits in pci_scan_device() and remove the pci_read_config() in pci_setup_device()?
> + > /* Assume 32-bit PCI; let 64-bit PCI cards (which are far rarer) > set this higher, assuming the system even supports it. */ > dev->dma_mask = 0xffffffff; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index fbf3766..9847936 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -138,6 +138,7 @@ struct pci_dev { > unsigned short subsystem_vendor; > unsigned short subsystem_device; > unsigned int class; /* 3 bytes: (base,sub,prog-if) */ > + u8 revision; /* PCI revision, low byte of class word */
If anyone doesn't want to add this, "class" really only uses 24 bits. ie could be packed together with revision field like they are in PCI configuration header.
thanks, grant
> u8 hdr_type; /* PCI header type (`multi' flag masked out) */ > u8 rom_base_reg; /* which config register controls the ROM */ > u8 pin; /* which interrupt pin this device uses */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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