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Message-ID: <20141022225913.GA4795@google.com>
Date: Wed, 22 Oct 2014 16:59:13 -0600
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Alexander Gordeev <agordeev@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH] PCI/MSI: Remove pci_enable_msix()
On Fri, Oct 10, 2014 at 05:35:43PM +0200, Alexander Gordeev wrote:
> There are no users of pci_enable_msix() function left. Obsolete
> it in favor of pci_enable_msix_range() and pci_enable_msix_exact()
> functions.
>
> Signed-off-by: Alexander Gordeev <agordeev@...hat.com>
> Cc: linux-pci@...r.kernel.org
Applied to pci/msi for v3.19, thanks!
> ---
> Documentation/PCI/PCIEBUS-HOWTO.txt | 15 +++---
> Documentation/PCI/pci.txt | 14 +++---
> drivers/pci/msi.c | 91 +++++++++++++++----------------------
> include/linux/pci.h | 4 --
> 4 files changed, 51 insertions(+), 73 deletions(-)
>
> diff --git a/Documentation/PCI/PCIEBUS-HOWTO.txt b/Documentation/PCI/PCIEBUS-HOWTO.txt
> index 6bd5f37..873a84a 100644
> --- a/Documentation/PCI/PCIEBUS-HOWTO.txt
> +++ b/Documentation/PCI/PCIEBUS-HOWTO.txt
> @@ -190,13 +190,14 @@ in the field interrupt_mode of struct pcie_device.
> 6.2 MSI-X Vector Resources
>
> Similar to the MSI a device driver for an MSI-X capable device can
> -call pci_enable_msix to request MSI-X interrupts. All service drivers
> -are not permitted to switch interrupt mode on its device. The PCI
> -Express Port Bus driver is responsible for determining the interrupt
> -mode and this should be transparent to service drivers. Any attempt
> -by service driver to call pci_enable_msix/pci_disable_msix may
> -result unpredictable behavior. Service drivers should use
> -(struct pcie_device*)dev->irq and call request_irq/free_irq.
> +call pci_enable_msix_range to request MSI-X interrupts. All service
> +drivers are not permitted to switch interrupt mode on its device.
> +The PCI Express Port Bus driver is responsible for determining the
> +interrupt mode and this should be transparent to service drivers.
> +Any attempt by service driver to call pci_enable_msix_range or
> +pci_disable_msix may result unpredictable behavior. Service drivers
> +should use (struct pcie_device*)dev->irq and call request_irq or
> +free_irq.
>
> 6.3 PCI Memory/IO Mapped Regions
>
> diff --git a/Documentation/PCI/pci.txt b/Documentation/PCI/pci.txt
> index 9518006..eb57f0a 100644
> --- a/Documentation/PCI/pci.txt
> +++ b/Documentation/PCI/pci.txt
> @@ -383,18 +383,18 @@ The fundamental difference between MSI and MSI-X is how multiple
> "vectors" get allocated. MSI requires contiguous blocks of vectors
> while MSI-X can allocate several individual ones.
>
> -MSI capability can be enabled by calling pci_enable_msi() or
> -pci_enable_msix() before calling request_irq(). This causes
> +MSI capability can be enabled by calling pci_enable_msi_range() or
> +pci_enable_msix_range() before calling request_irq(). This causes
> the PCI support to program CPU vector data into the PCI device
> capability registers.
>
> If your PCI device supports both, try to enable MSI-X first.
> Only one can be enabled at a time. Many architectures, chip-sets,
> -or BIOSes do NOT support MSI or MSI-X and the call to pci_enable_msi/msix
> -will fail. This is important to note since many drivers have
> -two (or more) interrupt handlers: one for MSI/MSI-X and another for IRQs.
> -They choose which handler to register with request_irq() based on the
> -return value from pci_enable_msi/msix().
> +or BIOSes do NOT support MSI or MSI-X and the call to pci_enable_msi_range()
> +or pci_enable_msix_range() will fail. This is important to note since many
> +drivers have two (or more) interrupt handlers: one for MSI/MSI-X and another
> +for IRQs. They choose which handler to register with request_irq() based on
> +the return value from pci_enable_msi_range() or pci_enable_msix_range().
>
> There are (at least) two really good reasons for using MSI:
> 1) MSI is an exclusive interrupt vector by definition.
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 2f7c92c..0df0ce1 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -903,58 +903,6 @@ int pci_msix_vec_count(struct pci_dev *dev)
> }
> EXPORT_SYMBOL(pci_msix_vec_count);
>
> -/**
> - * pci_enable_msix - configure device's MSI-X capability structure
> - * @dev: pointer to the pci_dev data structure of MSI-X device function
> - * @entries: pointer to an array of MSI-X entries
> - * @nvec: number of MSI-X irqs requested for allocation by device driver
> - *
> - * Setup the MSI-X capability structure of device function with the number
> - * of requested irqs upon its software driver call to request for
> - * MSI-X mode enabled on its hardware device function. A return of zero
> - * indicates the successful configuration of MSI-X capability structure
> - * with new allocated MSI-X irqs. A return of < 0 indicates a failure.
> - * Or a return of > 0 indicates that driver request is exceeding the number
> - * of irqs or MSI-X vectors available. Driver should use the returned value to
> - * re-send its request.
> - **/
> -int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
> -{
> - int nr_entries;
> - int i, j;
> -
> - if (!pci_msi_supported(dev, nvec))
> - return -EINVAL;
> -
> - if (!entries)
> - return -EINVAL;
> -
> - nr_entries = pci_msix_vec_count(dev);
> - if (nr_entries < 0)
> - return nr_entries;
> - if (nvec > nr_entries)
> - return nr_entries;
> -
> - /* Check for any invalid entries */
> - for (i = 0; i < nvec; i++) {
> - if (entries[i].entry >= nr_entries)
> - return -EINVAL; /* invalid entry */
> - for (j = i + 1; j < nvec; j++) {
> - if (entries[i].entry == entries[j].entry)
> - return -EINVAL; /* duplicate entry */
> - }
> - }
> - WARN_ON(!!dev->msix_enabled);
> -
> - /* Check whether driver already requested for MSI irq */
> - if (dev->msi_enabled) {
> - dev_info(&dev->dev, "can't enable MSI-X (MSI IRQ already assigned)\n");
> - return -EINVAL;
> - }
> - return msix_capability_init(dev, entries, nvec);
> -}
> -EXPORT_SYMBOL(pci_enable_msix);
> -
> void pci_msix_shutdown(struct pci_dev *dev)
> {
> struct msi_desc *entry;
> @@ -1088,16 +1036,49 @@ EXPORT_SYMBOL(pci_enable_msi_range);
> * with new allocated MSI-X interrupts.
> **/
> int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
> - int minvec, int maxvec)
> + int minvec, int maxvec)
> {
> - int nvec = maxvec;
> + int i, j;
> + int nvec;
> int rc;
>
> + if (!pci_msi_supported(dev, minvec))
> + return -EINVAL;
> +
> + WARN_ON(!!dev->msix_enabled);
> +
> + /* Check whether driver already requested MSI irqs */
> + if (dev->msi_enabled) {
> + dev_info(&dev->dev,
> + "can't enable MSI-X (MSI already enabled)\n");
> + return -EINVAL;
> + }
> +
> if (maxvec < minvec)
> return -ERANGE;
> + else if (!entries)
> + return -EINVAL;
> +
> + nvec = pci_msix_vec_count(dev);
> + if (nvec < 0)
> + return nvec;
> + else if (nvec < minvec)
> + return -EINVAL;
> + else if (nvec > maxvec)
> + nvec = maxvec;
> +
> + /* Check for any invalid entries */
> + for (i = 0; i < nvec; i++) {
> + if (entries[i].entry >= nvec)
> + return -EINVAL; /* invalid entry */
> + for (j = i + 1; j < nvec; j++) {
> + if (entries[i].entry == entries[j].entry)
> + return -EINVAL; /* duplicate entry */
> + }
> + }
>
> do {
> - rc = pci_enable_msix(dev, entries, nvec);
> + rc = msix_capability_init(dev, entries, nvec);
> if (rc < 0) {
> return rc;
> } else if (rc > 0) {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 5be8db4..ad9b5d4 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1197,7 +1197,6 @@ int pci_msi_vec_count(struct pci_dev *dev);
> void pci_msi_shutdown(struct pci_dev *dev);
> void pci_disable_msi(struct pci_dev *dev);
> int pci_msix_vec_count(struct pci_dev *dev);
> -int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec);
> void pci_msix_shutdown(struct pci_dev *dev);
> void pci_disable_msix(struct pci_dev *dev);
> void pci_restore_msi_state(struct pci_dev *dev);
> @@ -1225,9 +1224,6 @@ static inline int pci_msi_vec_count(struct pci_dev *dev) { return -ENOSYS; }
> static inline void pci_msi_shutdown(struct pci_dev *dev) { }
> static inline void pci_disable_msi(struct pci_dev *dev) { }
> static inline int pci_msix_vec_count(struct pci_dev *dev) { return -ENOSYS; }
> -static inline int pci_enable_msix(struct pci_dev *dev,
> - struct msix_entry *entries, int nvec)
> -{ return -ENOSYS; }
> static inline void pci_msix_shutdown(struct pci_dev *dev) { }
> static inline void pci_disable_msix(struct pci_dev *dev) { }
> static inline void pci_restore_msi_state(struct pci_dev *dev) { }
> --
> 1.8.3.1
>
> --
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