Re: [RFC Patch V1 11/12] genirq, PCI: Reorginize struct msi_desc to prepare for support of generic MSI

[Marc Zyngier <marc.zyngier@arm.com>]

Hi Gerry,

On 09/07/15 09:00, Jiang Liu wrote:
> Reorganize struct msi_desc so it could be reused by other MSI drivers.
> 
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> ---
>  include/linux/msi.h |   41 +++++++++++++++++++++--------------------
>  1 file changed, 21 insertions(+), 20 deletions(-)
> 
> diff --git a/include/linux/msi.h b/include/linux/msi.h
> index 5f77e231f515..f6845bc83774 100644
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -19,29 +19,30 @@ void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
>  void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
>  
>  struct msi_desc {
> -	struct {
> -		__u8	is_msix	: 1;
> -		__u8	multiple: 3;	/* log2 num of messages allocated */
> -		__u8	multi_cap : 3;	/* log2 num of messages supported */
> -		__u8	maskbit	: 1;	/* mask-pending bit supported ? */
> -		__u8	is_64	: 1;	/* Address size: 0=32bit 1=64bit */
> -		__u16	entry_nr;	/* specific enabled entry */
> -		unsigned default_irq;	/* default pre-assigned irq */
> -	} msi_attrib;
> -
> -	u32 masked;			/* mask bits */
> -	unsigned int irq;
> -	unsigned int nvec_used;		/* number of messages */
> -	struct list_head list;
> +	struct list_head		list;
> +	unsigned int			irq;
> +	unsigned int			nvec_used;	/* number of messages */
> +	struct device *			dev;
> +	struct msi_msg			msg;		/* Last set MSI message */
>  
>  	union {
> -		void __iomem *mask_base;
> -		u8 mask_pos;
> +		struct {				/* For PCI MSI/MSI-X */
> +			u32 masked;			/* mask bits */
> +			struct {
> +				__u8	is_msix	: 1;
> +				__u8	multiple: 3;	/* log2 num of messages allocated */
> +				__u8	multi_cap : 3;	/* log2 num of messages supported */
> +				__u8	maskbit	: 1;	/* mask-pending bit supported ? */
> +				__u8	is_64	: 1;	/* Address size: 0=32bit 1=64bit */
> +				__u16	entry_nr;	/* specific enabled entry */
> +				unsigned default_irq;	/* default pre-assigned irq */
> +			} msi_attrib;
> +			union {
> +				u8	mask_pos;
> +				void __iomem *mask_base;
> +			};
> +		};

Is this union the location where you would expect some non-PCI MSI
infrastructure to store their own data? If that's the case, maybe a
small comment to that effect would be good, as it is not completely
obvious from looking at the data structure.

>  	};
> -	struct device *dev;
> -
> -	/* Last set MSI message */
> -	struct msi_msg msg;
>  };
>  
>  /* Helpers to hide struct msi_desc implementation details */
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...