Re: [PATCH] platform-msi: Add ABI to show msi_irqs of platform devices

From: Greg KH
Date: Thu Aug 12 2021 - 03:24:47 EST


On Thu, Aug 12, 2021 at 04:19:30PM +1200, Barry Song wrote:
> > But why isn't this all handled by the MSI core code? Why would each bus
> > need to have this logic in it?
>
> i think i can extract some common code for sysfs populate/destroy to msi core from pci and platform.
> but we still need some pci/platform specific code in pci-msi and platform-msi cores. for example,
> pci-msi has specific data which will be accessed in its show() entry.
>
> struct msi_desc {
> ...
> union {
> /* PCI MSI/X specific data */
> struct {
> u32 masked;
> struct {
> u8 is_msix : 1;
> u8 multiple : 3;
> u8 multi_cap : 3;
> u8 maskbit : 1;
> u8 is_64 : 1;
> u8 is_virtual : 1;
> u16 entry_nr;
> unsigned default_irq;
> } msi_attrib;
> union {
> u8 mask_pos;
> void __iomem *mask_base;
> };
> };
>
> ...
> struct platform_msi_desc platform;
> ...
> };
> };
>
> in addition, they are quite different in initialization/release and also need different places to save sysfs groups.
> so probably i can let msi cores provide msi_populate_sysfs() and msi_destroy_sysfs() APIs. And ask pci and platform
> to call msi_populate_sysfs() in their init code and save the groups in their specific pointers, and then they can
> free sysfs in their release paths by calling msi_destroy_sysfs()

Ok, if this isn't easy then I guess it's not a big deal, but you should
go through the MSI developers first.

Why does a platform device have MSI interrupts? I thought they were
only for PCI devices.

thanks,

greg k-h