multiple separate pci bridges ...
benh at kernel.crashing.org
Sat Jan 3 10:56:57 EST 2004
On Sat, 2004-01-03 at 02:18, Rob Baxter wrote:
> Synergy Microsystems has designs with the Discovery 2 as well. We worked
> around this by setting pci_assign_all_busses to true and with modifications
> to the platform specific config cycle routines (only included one as an
> gemini_pcibios_bus_fixup(struct pci_dev *dev, struct pci_controller *hose)
> return ((dev->bus->number == hose->first_busno) ? 0 : dev->bus->number);
> gemini_pcibios_read_config_byte(struct pci_dev *dev, int offset, u8 *val)
> unsigned long reg;
> unsigned int addr;
> int bus;
> struct pci_controller *hose;
> hose = dev->sysdata;
> bus = gemini_pcibios_bus_fixup(dev, hose);
> addr = pci_config_type1_addr(bus, dev->devfn, offset & ~(0x3));
> reg = config_read(addr, hose->cfg_addr, hose->cfg_data);
> *val = ((reg >> ((offset & 0x3) << 3)) & 0xff);
> return PCIBIOS_SUCCESSFUL;
Hrm... Why this bus fixup thing ? Why not just clearly writing
if (dev->bus->number == hose->first_busno)
And those could be inline...
Also, the way you define functions with a name that "looks" like a
generic function (pci_config_type1_addr) is rather ugly...
> It is also necessary to set the first and last bus number fields of the
> hose structure correctly in your platform specific code. These will get
> over written later by the PCI driver code, and in our case, to the same
> values. Our platform specific code does a preliminary scan of the PCI
> buses to find the first and last bus numbers.
Why would you need to set them correctly ? The PCI code will set them
to sensible values before doing the bus scan and will fixup the last
busno afterward for each controller, you do not need any pre-scan or
whatever and you can leave those values to 0 at init time.
> This will also work when a PtP bridge is located on either of the primary
> PCI buses of the Discovery. We're using a derivative of a 2.4.19 kernel.
Yup, that should work fine.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
More information about the Linuxppc-dev