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SubjectRe: [PATCH v6 3/4] block: implement runtime pm strategy
On Tue, Jan 08, 2013 at 10:22:45AM -0500, Alan Stern wrote:
> Just as importantly, all of the public routines added in patch 2/4 to
> blk-core.c should have kerneldoc explaining how and where to use them.
> In particular, the kerneldoc for blk_pm_runtime_init() has to mention
> that the block runtime PM implementation works only for drivers that
> use request structures for their I/O; it doesn't work for drivers that
> use bio's directly.

How about the following description for them?

/**
* blk_pm_runtime_init - Block layer runtime PM initialization routine
* @q: the queue of the device
* @dev: the device the queue belongs to
*
* Description:
* Initialize runtime PM related fields for @q and start auto suspend
* for @dev. Drivers that want to take advantage of request based runtime
* PM should call this function after @dev has been initialized, and its
* request queue @q has been allocated, and runtime PM for it is not
* ready yet(either disabled/forbidden or its usage count >= 0).
*
* The block layer runtime PM is request based, so only works for drivers
* that use request as their IO unit instead of those directly use bio's.
*/

/**
* blk_pre_runtime_suspend - Pre runtime suspend check
* @q: the queue of the device
*
* Description:
* This function will check if runtime suspend is allowed for the device
* by examining if there are any requests pending in the queue. If there
* are requests pending, the device can not be runtime suspended; otherwise,
* the queue's status will be updated to SUSPENDING and the driver can
* proceed to suspend the device.
*
* For the not allowed case, we mark last busy for the device so that
* runtime PM core will try to autosuspend it some time later.
*
* This function should be called in the device's runtime suspend callback,
* before its runtime suspend function is called.
*
* Return:
* 0 - OK to runtime suspend the device
* -EBUSY - Device should not be runtime suspended
*/

/**
* blk_post_runtime_suspend - Post runtime suspend processing
* @q: the queue of the device
* @err: return value of the device's runtime suspend function
*
* Description:
* Update the queue's runtime status according to the return value of the
* device's runtime suspend function.
*
* This function should be called in the device's runtime suspend callback,
* after its runtime suspend function is called.
*/

/**
* blk_pre_runtime_resume - Pre runtime resume processing
* @q: the queue of the device
*
* Description:
* Update the queue's runtime status to RESUMING in preparation for the
* runtime resume of the device.
*
* This function should be called in the device's runtime resume callback,
* before its runtime resume function is called.
*/

/**
* blk_post_runtime_resume - Post runtime resume processing
* @q: the queue of the device
* @err: return value of the device's runtime resume function
*
* Description:
* Update the queue's runtime status according to the return value of the
* device's runtime resume function. If it is successfully resumed, process
* the requests that are queued into the device's queue when it is resuming
* and then mark last busy and initiate autosuspend for it.
*
* This function should be called in the device's runtime resume callback,
* after its runtime resume function is called.
*/

Please feel free to suggest, thanks.

-Aaron



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