Re: [RFC V2] xen: interface: introduce pvclk interface

From: Juergen Gross <jgross@suse.com>
To: Peng Fan <van.freenix@gmail.com>, xen-devel@lists.xenproject.org
Cc: Julien Grall <julien.grall@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	David Vrabel <david.vrabel@citrix.com>,
	Ian Campbell <ian.campbell@citrix.com>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [RFC V2] xen: interface: introduce pvclk interface
Date: Wed, 20 Jan 2016 10:05:15 +0100	[thread overview]
Message-ID: <569F4DCB.2030701@suse.com> (raw)
In-Reply-To: <1453278682-8750-1-git-send-email-van.freenix@gmail.com>

On 20/01/16 09:31, Peng Fan wrote:
> Introduce pvclk interface which is useful when doing device passthrough
> on ARM platform.

...

> +/*
> + * Frontend request
> + *
> + * cmd: command for operation on clk, should be XEN_CLK_[xx],
> + *	excluding XEN_CLK_END. id is the
> + * id: clk id
> + * rate: clock rate. Used for set rate.

Which unit? Hz?

> + */
> +struct xen_clkif_request {
> +	uint32_t cmd;
> +	uint32_t id;
> +	uint64_t rate;
> +};
> +typedef struct xen_clkif_request xen_clkif_request_t;
> +
> +/*
> + * Backend response
> + *
> + * cmd: command for operation on clk, same with the cmd in request.
> + * id: clk id, same with the id in request.
> + * success: indicate failure or success for the cmd.

Values?

> + * rate: clock rate. Used for get rate.
> + *
> + * cmd and id are filled by backend and passed to frontend to
> + * let frontend check whether the response is for the current
> + * request or not.

I'd rather let the frontend add a request Id to the request which
will be echoed here instead cmd and clock Id.

Juergen