Thread (112 messages) flat view 112 messages, 18 authors, 2023-01-15

Re: [patch V2 43/46] genirq/msi: Provide and use msi_domain_set_default_info_flags()

From: Marc Zyngier <maz@kernel.org>
Date: 2020-08-27 08:17:37
Also in: linux-iommu, linux-pci, lkml, xen-devel

On 2020-08-26 12:17, Thomas Gleixner wrote:
quoted hunk ↗ jump to hunk
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 <redacted>
---
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.
-- 
Jazz is not dead. It just smells funny...
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