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SubjectRe: [RFC V1 2/7] drivers/base: Introduce callbacks for IMS interrupt domain
On Thu, Sep 12, 2019 at 06:32:03PM -0700, Megha Dey wrote:
> This patch serves as a preparatory patch to introduce a new IMS
> (Interrupt Message Store) domain. It consists of APIs which would
> be used as callbacks to the IRQ chip associated with the IMS domain.
>
> The APIs introduced in this patch are:
> dev_ims_mask_irq - Generic irq chip callback to mask IMS interrupts
> dev_ims_unmask_irq - Generic irq chip callback to unmask IMS interrupts
> dev_ims_domain_write_msg - Helper to write MSI message to Device IMS
>
> It also introduces IMS specific structures namely:
> dev_ims_ops - Callbacks for IMS domain ops
> dev_ims_desc - Device specific IMS msi descriptor data
> dev_ims_priv_data - Internal data structure containing a unique devid
> and a pointer to the IMS domain ops
>
> Lastly, it adds a new config option MSI_IMS which must be enabled by
> any driver who would want to use the IMS infrastructure.
>
> Since IMS is not PCI compliant (like platform-msi), most of the code is
> similar to platform-msi.c.
>
> TODO: Conclude if ims-msi.c and platform-msi.c can be merged.
>
> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
> Signed-off-by: Megha Dey <megha.dey@linux.intel.com>
> ---
> drivers/base/Kconfig | 7 ++++
> drivers/base/Makefile | 1 +
> drivers/base/ims-msi.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/msi.h | 35 ++++++++++++++++++-
> 4 files changed, 136 insertions(+), 1 deletion(-)
> create mode 100644 drivers/base/ims-msi.c
>
> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
> index dc40449..038fabd 100644
> --- a/drivers/base/Kconfig
> +++ b/drivers/base/Kconfig
> @@ -206,3 +206,10 @@ config GENERIC_ARCH_TOPOLOGY
> runtime.
>
> endmenu
> +
> +config MSI_IMS
> + bool "Device Specific Interrupt Message Storage (IMS)"
> + select GENERIC_MSI_IRQ
> + help
> + This allows device drivers to enable device specific
> + interrupt message storage (IMS) besides standard MSI-X interrupts.

This text tells me nothing about if I want to enable this or not. How
is a user (or even a developer) supposed to know if their hardware
requires this?

And I _really_ dont want to see this in drivers/base/ if at all possible
because suddenly I am responsible for this code that I know nothing
about.

greg k-h

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