On Sun, Mar 4, 2012 at 1:02 AM, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
> A runtime suspend of an MMC controller belonging to a power domain
> or, in a more complicated scenario, a runtime suspend of another
> device in the same power domain, may cause power to be removed from
> the entire domain. In that case, the amount of time necessary to
> runtime-resume the MMC controller is often substantially greater
> than the time needed to enable its clock. That may hurt performance
> in some situations, because user data may need to wait for the
> controller to become operational, so we should make it possible to
> prevent that from happening.
>
> For this reason, introduce a new sysfs attribute for MMC hosts,
> pm_latency_limit_ms, allowing user space to specify the upper bound
> of the time necessary to bring the host up after it has been
> runtime-suspended. However, make it appear ony for the hosts whose
> drivers declare support for PM QoS by populating the pm_qos_req
> member of struct mmc_host before registering the host.
>
> Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
Overall I've already ACKed this I think, looking good...
Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> @@ -191,6 +192,10 @@ struct mmc_host {
> u32 ocr_avail_mmc; /* MMC-specific OCR */
> struct notifier_block pm_notify;
>
> + struct dev_pm_qos_request *pm_qos_req;
> + s32 pm_qos_val;
> + struct device_attribute pm_qos_val_attr;
> +
> #define MMC_VDD_165_195 0x00000080 /* VDD voltage 1.65 - 1.95 */
> #define MMC_VDD_20_21 0x00000100 /* VDD voltage 2.0 ~ 2.1 */
> #define MMC_VDD_21_22 0x00000200 /* VDD voltage 2.1 ~ 2.2 */
As you can see from the members around there we try to document
the members whenever the meaning is non-trivial.
So pm_qos_val could need
/* QoS maximum power-on delay in ms */
(The entire struct host should of course be converted to use kerneldoc
but right now the pattern is like that.)
> Index: linux/Documentation/mmc/mmc-dev-attrs.txt
Well documented!
Yours,
Linus Walleij
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