On 11 April 2013 10:31, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> On 08/04/13 14:44, Ulf Hansson wrote:
>> From: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>>
>> Once the mmc blkdevice is being probed, runtime pm will be enabled.
>> By using runtime autosuspend, the power save operations can be done
>> when request inactivity occurs for a certain time. Right now the
>> selected timeout value is set to 3 s.
>>
>> Moreover, when the blk device is being suspended, we make sure the device
>> will be runtime resumed. The reason for doing this is that we want the
>> host suspend sequence to be unaware of any runtime power save operations,
>> so it can just handle the suspend as the device is fully powered from a
>> runtime perspective.
>>
>> This patch is preparing to make it possible to move BKOPS handling into
>> the runtime callbacks for the mmc bus_ops. Thus IDLE BKOPS can be
>> accomplished.
>>
>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>> Acked-by: Maya Erez <merez@xxxxxxxxxxxxxx>
>> Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
>> Acked-by: Kevin Liu <kliu5@xxxxxxxxxxx>
>> ---
>> drivers/mmc/card/block.c | 28 ++++++++++++++++++++++++++--
>> 1 file changed, 26 insertions(+), 2 deletions(-)
>>
>
> There are debugfs uses of the card also (e.g.mmc_dbg_card_status_get)
> that will need get/put added.
In the end it all depends on what kind of operations you decide to do
in the runtime_supend|resume callbacks.
Since the callbacks is not yet implemented for sd and mmc, this is not
required as of now.
Nevertheless a most valid point that needs to be considered, while
implementing the callbacks. Thanks for pointing this out.
>
> There might be others. Please check.
mmc_rescan needs to be considered at card removal and at resume. But,
again this does not need to be handled as of now.
>
> It might be worth adding helpers e.g. mmc_claim_card()/mmc_release_card
> so that it is easy to see the places that the host is claimed but runtime pm
> is not used.
I am not sure we gain more visibility adding helpers at this initial
step. We already have three scenarios for get/claim.
1. mmc_claim_host and pm_runtime_get is done in conjuction.
2. only mmc_claim_host.
3. only pm_runtime_get.
For put, we have a similar situation, and we don't even use the same
runtime put API for all cases.
I see your point, it could very well be wanted to add these helpers if
we see that the callbacks force the pm_runtime API to be used from
several more places.
>
> void mmc_claim_card(card)
> {
> pm_runtime_get_sync(&card->dev);
> mmc_claim_host(card->host);
> }
>
> void mmc_release_card(card)
> {
> mmc_release_host(card->host);
> pm_runtime_mark_last_busy(&card->dev);
> pm_runtime_put_autosuspend(&card->dev);
> }
>
>
>
Kind regards
Ulf Hansson
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