| Message ID | 20200826112334.889315931@linutronix.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | x86, PCI, XEN, genirq ...: Prepare for device MSI | expand |
On 2020-08-26 12:17, Thomas Gleixner wrote: > MSI interrupts have some common flags which should be set not only for > PCI/MSI interrupts. > > Move the PCI/MSI flag setting into a common function so it can be > reused. > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > V2: New patch > --- > drivers/pci/msi.c | 7 +------ > include/linux/msi.h | 1 + > kernel/irq/msi.c | 24 ++++++++++++++++++++++++ > 3 files changed, 26 insertions(+), 6 deletions(-) > > --- a/drivers/pci/msi.c > +++ b/drivers/pci/msi.c > @@ -1469,12 +1469,7 @@ struct irq_domain *pci_msi_create_irq_do > if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS) > pci_msi_domain_update_chip_ops(info); > > - info->flags |= MSI_FLAG_ACTIVATE_EARLY; > - if (IS_ENABLED(CONFIG_GENERIC_IRQ_RESERVATION_MODE)) > - info->flags |= MSI_FLAG_MUST_REACTIVATE; > - > - /* PCI-MSI is oneshot-safe */ > - info->chip->flags |= IRQCHIP_ONESHOT_SAFE; > + msi_domain_set_default_info_flags(info); > > domain = msi_create_irq_domain(fwnode, info, parent); > if (!domain) > --- a/include/linux/msi.h > +++ b/include/linux/msi.h > @@ -410,6 +410,7 @@ int platform_msi_domain_alloc(struct irq > void platform_msi_domain_free(struct irq_domain *domain, unsigned int > virq, > unsigned int nvec); > void *platform_msi_get_host_data(struct irq_domain *domain); > +void msi_domain_set_default_info_flags(struct msi_domain_info *info); > #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */ > > #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN > --- a/kernel/irq/msi.c > +++ b/kernel/irq/msi.c > @@ -70,6 +70,30 @@ void get_cached_msi_msg(unsigned int irq > EXPORT_SYMBOL_GPL(get_cached_msi_msg); > > #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN > +void msi_domain_set_default_info_flags(struct msi_domain_info *info) > +{ > + /* Required so that a device latches a valid MSI message on startup > */ > + info->flags |= MSI_FLAG_ACTIVATE_EARLY; As far as I remember the story behind this flag (it's been a while), it was working around a PCI-specific issue, hence being located in the PCI code. Now, the "program the MSI before enabling it" concept makes sense no matter what bus this is on, and I wonder why we are even keeping this flag around. Can't we just drop it together with the check in msi_domain_alloc_irqs()? Thanks, M.
On Thu, Aug 27 2020 at 09:17, Marc Zyngier wrote: > On 2020-08-26 12:17, Thomas Gleixner wrote: >> #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN >> +void msi_domain_set_default_info_flags(struct msi_domain_info *info) >> +{ >> + /* Required so that a device latches a valid MSI message on startup >> */ >> + info->flags |= MSI_FLAG_ACTIVATE_EARLY; > > As far as I remember the story behind this flag (it's been a while), > it was working around a PCI-specific issue, hence being located in > the PCI code. Yes. Some cards misbehave when there is no valid message programmed and MSI is enabled. > Now, the "program the MSI before enabling it" concept makes sense no > matter what bus this is on, and I wonder why we are even keeping this > flag around. > Can't we just drop it together with the check in > msi_domain_alloc_irqs()? I'm fine with that. Thanks, tglx
--- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -1469,12 +1469,7 @@ struct irq_domain *pci_msi_create_irq_do if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS) pci_msi_domain_update_chip_ops(info); - info->flags |= MSI_FLAG_ACTIVATE_EARLY; - if (IS_ENABLED(CONFIG_GENERIC_IRQ_RESERVATION_MODE)) - info->flags |= MSI_FLAG_MUST_REACTIVATE; - - /* PCI-MSI is oneshot-safe */ - info->chip->flags |= IRQCHIP_ONESHOT_SAFE; + msi_domain_set_default_info_flags(info); domain = msi_create_irq_domain(fwnode, info, parent); if (!domain) --- a/include/linux/msi.h +++ b/include/linux/msi.h @@ -410,6 +410,7 @@ int platform_msi_domain_alloc(struct irq void platform_msi_domain_free(struct irq_domain *domain, unsigned int virq, unsigned int nvec); void *platform_msi_get_host_data(struct irq_domain *domain); +void msi_domain_set_default_info_flags(struct msi_domain_info *info); #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */ #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN --- a/kernel/irq/msi.c +++ b/kernel/irq/msi.c @@ -70,6 +70,30 @@ void get_cached_msi_msg(unsigned int irq EXPORT_SYMBOL_GPL(get_cached_msi_msg); #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN +void msi_domain_set_default_info_flags(struct msi_domain_info *info) +{ + /* Required so that a device latches a valid MSI message on startup */ + info->flags |= MSI_FLAG_ACTIVATE_EARLY; + + /* + * Interrupt reservation mode allows to stear the MSI message of an + * inactive device to a special (usually spurious interrupt) target. + * This allows to prevent interrupt vector exhaustion e.g. on x86. + * But (PCI)MSI interrupts are activated early - see above - so the + * interrupt request/startup sequence would not try to allocate a + * usable vector which means that the device interupts would end + * up on the special vector and issue spurious interrupt messages. + * Setting the reactivation flag ensures that when the interrupt + * is requested the activation is invoked again so that a real + * vector can be allocated. + */ + if (IS_ENABLED(CONFIG_GENERIC_IRQ_RESERVATION_MODE)) + info->flags |= MSI_FLAG_MUST_REACTIVATE; + + /* MSI is oneshot-safe at least in theory */ + info->chip->flags |= IRQCHIP_ONESHOT_SAFE; +} + static inline void irq_chip_write_msi_msg(struct irq_data *data, struct msi_msg *msg) {
MSI interrupts have some common flags which should be set not only for PCI/MSI interrupts. Move the PCI/MSI flag setting into a common function so it can be reused. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- V2: New patch --- drivers/pci/msi.c | 7 +------ include/linux/msi.h | 1 + kernel/irq/msi.c | 24 ++++++++++++++++++++++++ 3 files changed, 26 insertions(+), 6 deletions(-)