Re: [coreboot] pci_device.c cleanup

[Myles Watson]

> -----Original Message-----
> From: Carl-Daniel Hailfinger [mailto:[e-mail]]
> Sent: Tuesday, November 04, 2008 5:09 PM
> To: Myles Watson
> Cc: Coreboot
> Subject: Re: [coreboot] pci_device.c cleanup
>
> On 04.11.2008 21:04, Myles Watson wrote:
> > This patch clarifies/adds comments and changes names in
>
> device/pci_device.c
> > It also changes %p debug statements in various places.  I think they get
>
> in
> > the way of diffs when you have log files to compare.  I don't want to
>
> see
> > the
> > allocation differences most of the time.  I turned most of them into
>
> NULL
> > checks.  If they were supposed to be "Where are we in device
>
> allocation?"
> > checks, we could make them into that too.
> >
> > It's a work-in-progress. Comments welcome.
> >
> > I think most of the changes are self explanatory, but this one might not
>
> be:
> > If you are reading all the BARs from a device, and you come to a 64-bit
>
> BAR.
> > No matter why you skip it, you should skip it as a 64-bit BAR, and not
>
> try
> > to
> > read the upper half as the next 32-bit BAR.
> >
> > Because of that, set the 64-bit flag IORESOURCE_PCI64 early, and don't
>
> clear
> > it on return.
> >
> > Signed-off-by: Myles Watson
> >
> > @@ -899,18 +924,18 @@
> > Given a linked list of PCI device structures and a devfn number,
>
> find the
> > device structure correspond to the devfn, if present. This function
>
> also
> > removes the device structure from the linked list.
> > @param list The device structure list.
> > @param devfn A device/function number.
> > @return Pointer to the device structure found or NULL of we have not
> >   allocated a device for this devfn yet.
> > */
> >
> > -static struct device *pci_scan_get_dev(struct device **list, unsigned
>
> int devfn)
> > +static struct device *pci_get_dev(struct device **list, unsigned int
>
> devfn)
> > {
> >    struct device *dev;
> >    dev = 0;
> > printk(BIOS_SPEW, "%s: list is %p, *list is %p\n", __func__, list,
> >       *list);
> > printk(BIOS_SPEW, "%s: list is %sNULL, *list is %sNULL\n", __func__,
> > list?"NOT ":"", *list?"NOT ":"");
> > for (; *list; list = &(*list)->sibling) {
> > printk(BIOS_SPEW, "%s: check dev %s \n", __func__,
> >       (*list)->dtsname);
>
> Was that change really intentional? Sure, it makes diffing easier, but
> some diagnostics (especially considering the still buggy device
> enumeration) are now more difficult.

Since this is looking through the list of children, and the function prints
out the dtsname of each child, I didn't find the actual pointer to be
useful.  The dtsname is much more useful.
> > @@ -1043,15 +1068,22 @@
> >    dev->irq_pin = pci_read_config8(dev, PCI_INTERRUPT_PIN);
> >    dev->min_gnt = pci_read_config8(dev, PCI_MIN_GNT);
> >    dev->max_lat = pci_read_config8(dev, PCI_MAX_LAT);
> > -#warning Per-device subsystem ID should only be read from the device if
>
> none has been specified for the device in the dts.
> > dev->subsystem_vendor = pci_read_config16(dev,
>
> PCI_SUBSYSTEM_VENDOR_ID);
> > dev->subsystem_device = pci_read_config16(dev, PCI_SUBSYSTEM_ID);
> >
> > /* Store the interesting information in the device structure. */
> > /*Per-device subsystem ID should only be read from the device if
>
> none
> > * has been specified for the device in the dts.
> > */
> > if (!dev->subsystem_vendor && !dev->subsystem_device) {
> > dev->subsystem_vendor =
> > 		pci_read_config16(dev,

PCI_SUBSYSTEM_VENDOR_ID);
> > dev->subsystem_device =
> > 		pci_read_config16(dev, PCI_SUBSYSTEM_ID);
> > }
> > dev->id.type = DEVICE_ID_PCI;
> >  dev->id.pci.vendor = id & 0xffff;
> >  dev->id.pci.device = (id >> 16) & 0xffff;
> >  dev->hdr_type = hdr_type;
> > /* Class code, the upper 3 bytes of PCI_CLASS_REVISION. */
> >  dev->class = class >> 8;
>
> Hm. Although you fixed the code as indicated in the #warning, I fear
> there's still something missing and that's the reason the warning was
> there. Where do we set the subsystem ID of the real device (not struct
> device)?

There's another place in the code where there's a warning that addresses
this same issue.  I didn't think we needed it in both places.
> > @@ -1105,6 +1135,8 @@
> >
> > printk(BIOS_DEBUG, "%s start bus %p, bus->dev %p\n", __func__, bus,
> >           bus->dev);
> >
> > +#warning This check needs checking.
> >    if (bus->dev->path.type != DEVICE_PATH_PCI_BUS)
> >    	printk(BIOS_ERR, "ERROR: pci_scan_bus called with incorrect

"
> >        "bus->dev->path.type, path is %s\n", dev_path(bus-
> >
> > dev));
>
> If you manage to fix the device code in a way which doesn't trigger this
> anymore, your static devices will suddenly be found. Since this check is
> only triggered if your code and/or device tree is really buggy, we could
> upgrade it to a die().

I realize it's a problem.  Since I removed a couple of the other warnings, I
thought I'd put one in this trouble spot.

Thanks for the review,

Myles