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

On Thu, Aug 27 2020 at 09:17, Marc Zyngier wrote:

On 2020-08-26 12:17, Thomas Gleixner wrote:

quoted

 #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