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PCI/portdrv: Consolidate comments

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Consolidate some repetitive comments so we can see the code better.  No
functional change.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Bjorn Helgaas 2017-10-19 16:09:26 -05:00
parent 7c950b9e53
commit b8acfd7c0f
1 changed files with 9 additions and 54 deletions
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63
drivers/pci/pcie/portdrv_core.c
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@ -56,40 +56,27 @@ static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
{
int nr_entries, entry, nvec = 0;
/*
* Allocate as many entries as the port wants, so that we can check
* which of them will be useful. Moreover, if nr_entries is correctly
* equal to the number of entries this port actually uses, we'll happily
* go through without any tricks.
*/
/* Allocate the maximum possible number of MSI/MSI-X vectors */
nr_entries = pci_alloc_irq_vectors(dev, 1, PCIE_PORT_MAX_MSI_ENTRIES,
PCI_IRQ_MSIX | PCI_IRQ_MSI);
if (nr_entries < 0)
return nr_entries;
/*
* The Interrupt Message Number indicates which vector is used, i.e.,
* the MSI-X table entry or the MSI offset between the base Message
* Data and the generated interrupt message. See PCIe r3.1, sec
* 7.8.2, 7.10.10, 7.31.2.
*/
if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
u16 reg16;
/*
* Per PCIe r3.1, sec 6.1.6, "PME and Hot-Plug Event
* interrupts (when both are implemented) always share the
* same MSI or MSI-X vector, as indicated by the Interrupt
* Message Number field in the PCI Express Capabilities
* register".
*
* Per sec 7.8.2, "For MSI, the [Interrupt Message Number]
* indicates the offset between the base Message Data and
* the interrupt message that is generated."
*
* "For MSI-X, the [Interrupt Message Number] indicates
* which MSI-X Table entry is used to generate the
* interrupt message."
*/
pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
entry = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
if (entry >= nr_entries)
goto out_free_irqs;
/* PME and hotplug share an MSI/MSI-X vector */
irqs[PCIE_PORT_SERVICE_PME_SHIFT] = pci_irq_vector(dev, entry);
irqs[PCIE_PORT_SERVICE_HP_SHIFT] = pci_irq_vector(dev, entry);
@ -99,19 +86,6 @@ static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
if (mask & PCIE_PORT_SERVICE_AER) {
u32 reg32, pos;
/*
* Per PCIe r3.1, sec 7.10.10, the Advanced Error Interrupt
* Message Number in the Root Error Status register
* indicates which MSI/MSI-X vector is used for AER.
*
* "For MSI, the [Advanced Error Interrupt Message Number]
* indicates the offset between the base Message Data and
* the interrupt message that is generated."
*
* "For MSI-X, the [Advanced Error Interrupt Message
* Number] indicates which MSI-X Table entry is used to
* generate the interrupt message."
*/
pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &reg32);
entry = (reg32 & PCI_ERR_ROOT_AER_IRQ) >> 27;
@ -126,19 +100,6 @@ static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
if (mask & PCIE_PORT_SERVICE_DPC) {
u16 reg16, pos;
/*
* Per PCIe r4.0 (v0.9), sec 7.9.15.2, the DPC Interrupt
* Message Number in the DPC Capability register indicates
* which MSI/MSI-X vector is used for DPC.
*
* "For MSI, the [DPC Interrupt Message Number] indicates
* the offset between the base Message Data and the
* interrupt message that is generated."
*
* "For MSI-X, the [DPC Interrupt Message Number] indicates
* which MSI-X Table entry is used to generate the
* interrupt message."
*/
pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC);
pci_read_config_word(dev, pos + PCI_EXP_DPC_CAP, &reg16);
entry = reg16 & PCI_EXP_DPC_IRQ;
@ -150,16 +111,10 @@ static int pcie_port_enable_irq_vec(struct pci_dev *dev, int *irqs, int mask)
nvec = max(nvec, entry + 1);
}
/*
* If nvec is equal to the allocated number of entries, we can just use
* what we have. Otherwise, the port has some extra entries not for the
* services we know and we need to work around that.
*/
/* If we allocated more than we need, free them and allocate fewer */
if (nvec != nr_entries) {
/* Drop the temporary MSI-X setup */
pci_free_irq_vectors(dev);
/* Now allocate the MSI-X vectors for real */
nr_entries = pci_alloc_irq_vectors(dev, nvec, nvec,
PCI_IRQ_MSIX | PCI_IRQ_MSI);
if (nr_entries < 0)