On Fri, Oct 23, 2015 at 1:31 PM, Bjorn Helgaas [off-list ref] wrote:

Hi Ley,

On Thu, Oct 22, 2015 at 05:27:28PM +0800, Ley Foon Tan wrote:

quoted

This patch adds the Altera PCIe host controller driver.

quoted

+static void altera_pcie_fixups(struct pci_bus *bus)
+{
+     struct pci_dev *dev;
+
+     list_for_each_entry(dev, &bus->devices, bus_list) {
+             altera_pcie_retrain(dev);
+             altera_pcie_fixup_res(dev);
+     }
+}

I'd really like to avoid this particular fixup because it's done
between pci_scan_root_bus() and pci_assign_unassigned_bus_resources()
and pci_bus_add_devices().  That path is almost 100% arch-independent,
and someday we should be able to pull all that out into one PCI core
interface.

You might be able to do the link retrain fixup as a header quirk.
That's not really ideal either, but I don't think we have a good
mechanism of inserting per-host bridge hooks in the enumeration path.
There are some pcibios_*() hooks, but those are per-arch, not per-host
bridge, so they're not really what you want here.

Okay, will change the retrain fixup to use *PCI_FIXUP* macro.
By doing this, we need [PATCH v11 2/6] pci: add Altera PCI vendor ID patch.

I think other host drivers have handled the "prevent enumeration of
root complex resources" problem by adding a similar check in the
config accessors.

Okay, will handle this in config accessors.

quoted

+static int altera_pcie_cfg_write(struct pci_bus *bus, unsigned int devfn,
+                              int where, int size, u32 value)

This needs a comment to the effect that this hardware can only generate
32-bit config accesses.  We also need a printk in the probe routine so
there's a note in dmesg so we have a clue that RW1C bits in config space
may be corrupted.

I have checked the PCIe/TLP spec, we can use the "First BE" (byte
enable) field in TLP packet to write
specific bytes only. And I have update driver to support this "First
BE" feature.
So, we don't have corrupted RW1C bit issue now.

quoted

+{
+     struct altera_pcie *pcie = bus->sysdata;
+     u32 data32;
+     u32 shift = 8 * (where & 3);
+     u8 byte_en;
+
+     if (!altera_pcie_valid_config(pcie, bus, PCI_SLOT(devfn)))
+             return PCIBIOS_DEVICE_NOT_FOUND;
+
+     switch (size) {
+     case 1:
+             data32 = (value & 0xff) << shift;
+             byte_en = 1 << (where & 3);
+             break;
+     case 2:
+             data32 = (value & 0xffff) << shift;
+             byte_en = 3 << (where & 3);
+             break;
+     default:
+             data32 = value;
+             byte_en = 0xf;
+             break;
+     }
+
+     return tlp_cfg_dword_write(pcie, bus->number, devfn,
+             (where & ~DWORD_MASK), byte_en, data32);
+}

quoted

+static void altera_pcie_isr(struct irq_desc *desc)
+{
+     struct irq_chip *chip = irq_desc_get_chip(desc);
+     struct altera_pcie *pcie;
+     unsigned long status;
+     u32 bit;
+     u32 virq;
+
+     chained_irq_enter(chip, desc);
+     pcie = irq_desc_get_handler_data(desc);
+
+     while ((status = cra_readl(pcie, P2A_INT_STATUS)
+             & P2A_INT_STS_ALL) != 0) {
+             for_each_set_bit(bit, &status, INTX_NUM) {
+                     /* clear interrupts */
+                     cra_writel(pcie, 1 << bit, P2A_INT_STATUS);
+
+                     virq = irq_find_mapping(pcie->irq_domain, bit + 1);
+                     if (virq)
+                             generic_handle_irq(virq);
+                     else
+                             dev_err(&pcie->pdev->dev, "unexpected IRQ\n");

Include the bit number here.  A printk string with no % substitutions
is rarely as useful as it could be.

Okay.

quoted

...
+     bus = pci_scan_root_bus(&pdev->dev, pcie->root_bus_nr, &altera_pcie_ops,
+                             pcie, &pcie->resources);
+     if (!bus)
+             return -ENOMEM;
+
+     altera_pcie_fixups(bus);
+     pci_fixup_irqs(pci_common_swizzle, of_irq_parse_and_map_pci);
+     pci_assign_unassigned_bus_resources(bus);
+     pci_bus_add_devices(bus);
+
+     /* Configure PCI Express setting. */
+     list_for_each_entry(child, &bus->children, node)
+             pcie_bus_configure_settings(child);

This loop should be before pci_bus_add_devices().  When we call
pci_bus_add_devices(), drivers may claim devices immediately, and the
PCI core shouldn't be changing device configuration while a driver
owns the device.

Okay, will move this before pci_bus_add_devices().

Thanks.

Regards
Ley Foon