From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f174.google.com ([209.85.217.174]:62208 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757393Ab2IGUx0 (ORCPT ); Fri, 7 Sep 2012 16:53:26 -0400 Received: by lbbgj3 with SMTP id gj3so97934lbb.19 for ; Fri, 07 Sep 2012 13:53:24 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <6a425d611ce5c276ec6949fd6aadf575580e07fe.1346653435.git.agordeev@redhat.com> References: <6a425d611ce5c276ec6949fd6aadf575580e07fe.1346653435.git.agordeev@redhat.com> From: Bjorn Helgaas Date: Fri, 7 Sep 2012 13:53:03 -0700 Message-ID: Subject: Re: [PATCH v2 -tip 4/5] PCI, MSI: Enable multiple MSIs with pci_enable_msi_block_auto() To: Alexander Gordeev Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner , Suresh Siddha , Yinghai Lu , Jeff Garzik , Matthew Wilcox , x86@kernel.org, linux-pci@vger.kernel.org, linux-ide@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-pci-owner@vger.kernel.org List-ID: On Mon, Sep 3, 2012 at 2:19 AM, Alexander Gordeev wrote: > The new function pci_enable_msi_block_auto() tries to allocate maximum > possible number of MSIs up to the number the device supports. It > generalizes a pattern when pci_enable_msi_block() is contiguously called > until it succeeds or fails. > > Opposite to pci_enable_msi_block() which takes the number of MSIs to > allocate as a input parameter, pci_enable_msi_block_auto() could be used > by device drivers to obtain the number of assigned MSIs and the number > of MSIs the device supports. > > Signed-off-by: Alexander Gordeev Acked-by: Bjorn Helgaas I haven't looked at the other patches in this series, but if the x86/IRQ folks like them, I'm OK with this part. Since the series is mostly non-PCI, I think it makes the most sense to keep it all together and merge it through some x86 or IRQ tree, including this PCI bit. > --- > Documentation/PCI/MSI-HOWTO.txt | 37 ++++++++++++++++++++++++++++++++----- > drivers/pci/msi.c | 26 ++++++++++++++++++++++++++ > include/linux/pci.h | 7 +++++++ > 3 files changed, 65 insertions(+), 5 deletions(-) > > diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt > index 53e6fca..a091780 100644 > --- a/Documentation/PCI/MSI-HOWTO.txt > +++ b/Documentation/PCI/MSI-HOWTO.txt > @@ -127,15 +127,42 @@ on the number of vectors that can be allocated; pci_enable_msi_block() > returns as soon as it finds any constraint that doesn't allow the > call to succeed. > > -4.2.3 pci_disable_msi > +4.2.3 pci_enable_msi_block_auto > + > +int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *count) > + > +This variation on pci_enable_msi() call allows a device driver to request > +the maximum possible number of MSIs. The MSI specification only allows > +interrupts to be allocated in powers of two, up to a maximum of 2^5 (32). > + > +If this function returns a positive number, it indicates that it has > +succeeded and the returned value is the number of allocated interrupts. In > +this case, the function enables MSI on this device and updates dev->irq to > +be the lowest of the new interrupts assigned to it. The other interrupts > +assigned to the device are in the range dev->irq to dev->irq + returned > +value - 1. > + > +If this function returns a negative number, it indicates an error and > +the driver should not attempt to request any more MSI interrupts for > +this device. > + > +If the device driver needs to know the number of interrupts the device > +supports it can pass the pointer count where that number is stored. The > +device driver must decide what action to take if pci_enable_msi_block_auto() > +succeeds, but returns a value less than the number of interrupts supported. > +If the device driver does not need to know the number of interrupts > +supported, it can set the pointer count to NULL. > + > +4.2.4 pci_disable_msi > > void pci_disable_msi(struct pci_dev *dev) > > This function should be used to undo the effect of pci_enable_msi() or > -pci_enable_msi_block(). Calling it restores dev->irq to the pin-based > -interrupt number and frees the previously allocated message signaled > -interrupt(s). The interrupt may subsequently be assigned to another > -device, so drivers should not cache the value of dev->irq. > +pci_enable_msi_block() or pci_enable_msi_block_auto(). Calling it restores > +dev->irq to the pin-based interrupt number and frees the previously > +allocated message signaled interrupt(s). The interrupt may subsequently be > +assigned to another device, so drivers should not cache the value of > +dev->irq. > > Before calling this function, a device driver must always call free_irq() > on any interrupt for which it previously called request_irq(). > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > index f0752d1..690b268 100644 > --- a/drivers/pci/msi.c > +++ b/drivers/pci/msi.c > @@ -845,6 +845,32 @@ int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec) > } > EXPORT_SYMBOL(pci_enable_msi_block); > > +int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec) > +{ > + int ret, pos, nvec; > + u16 msgctl; > + > + pos = pci_find_capability(dev, PCI_CAP_ID_MSI); > + if (!pos) > + return -EINVAL; > + > + pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl); > + ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); > + > + if (maxvec) > + *maxvec = ret; > + > + do { > + nvec = ret; > + ret = pci_enable_msi_block(dev, nvec); > + } while (ret > 0); > + > + if (ret < 0) > + return ret; > + return nvec; > +} > +EXPORT_SYMBOL(pci_enable_msi_block_auto); > + > void pci_msi_shutdown(struct pci_dev *dev) > { > struct msi_desc *desc; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 5faa831..b8a9454 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1070,6 +1070,12 @@ static inline int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec) > return -1; > } > > +static inline int > +pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec) > +{ > + return -1; > +} > + > static inline void pci_msi_shutdown(struct pci_dev *dev) > { } > static inline void pci_disable_msi(struct pci_dev *dev) > @@ -1101,6 +1107,7 @@ static inline int pci_msi_enabled(void) > } > #else > extern int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec); > +extern int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec); > extern void pci_msi_shutdown(struct pci_dev *dev); > extern void pci_disable_msi(struct pci_dev *dev); > extern int pci_msix_table_size(struct pci_dev *dev); > -- > 1.7.7.6 > > > -- > Regards, > Alexander Gordeev > agordeev@redhat.com