diff options
Diffstat (limited to 'Documentation/PCI/MSI-HOWTO.txt')
| -rw-r--r-- | Documentation/PCI/MSI-HOWTO.txt | 21 |
1 files changed, 6 insertions, 15 deletions
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index 0d920d54536d..1179850f453c 100644 --- a/Documentation/PCI/MSI-HOWTO.txt +++ b/Documentation/PCI/MSI-HOWTO.txt @@ -353,7 +353,7 @@ retry: rc = pci_enable_msix_range(adapter->pdev, adapter->msix_entries, maxvec, maxvec); /* - * -ENOSPC is the only error code allowed to be analized + * -ENOSPC is the only error code allowed to be analyzed */ if (rc == -ENOSPC) { if (maxvec == 1) @@ -370,7 +370,7 @@ retry: return rc; } -Note how pci_enable_msix_range() return value is analized for a fallback - +Note how pci_enable_msix_range() return value is analyzed for a fallback - any error code other than -ENOSPC indicates a fatal error and should not be retried. @@ -486,7 +486,7 @@ during development. If your device supports both MSI-X and MSI capabilities, you should use the MSI-X facilities in preference to the MSI facilities. As mentioned above, MSI-X supports any number of interrupts between 1 and 2048. -In constrast, MSI is restricted to a maximum of 32 interrupts (and +In contrast, MSI is restricted to a maximum of 32 interrupts (and must be a power of two). In addition, the MSI interrupt vectors must be allocated consecutively, so the system might not be able to allocate as many vectors for MSI as it could for MSI-X. On some platforms, MSI @@ -501,18 +501,9 @@ necessary to disable interrupts (Linux guarantees the same interrupt will not be re-entered). If a device uses multiple interrupts, the driver must disable interrupts while the lock is held. If the device sends a different interrupt, the driver will deadlock trying to recursively -acquire the spinlock. - -There are two solutions. The first is to take the lock with -spin_lock_irqsave() or spin_lock_irq() (see -Documentation/DocBook/kernel-locking). The second is to specify -IRQF_DISABLED to request_irq() so that the kernel runs the entire -interrupt routine with interrupts disabled. - -If your MSI interrupt routine does not hold the lock for the whole time -it is running, the first solution may be best. The second solution is -normally preferred as it avoids making two transitions from interrupt -disabled to enabled and back again. +acquire the spinlock. Such deadlocks can be avoided by using +spin_lock_irqsave() or spin_lock_irq() which disable local interrupts +and acquire the lock (see Documentation/DocBook/kernel-locking). 4.6 How to tell whether MSI/MSI-X is enabled on a device |