| Message ID | 20171102231551.16220-2-f.fainelli@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | pinctrl: Allow indicating loss of state across suspend/resume | expand |
On Fri, Nov 3, 2017 at 12:15 AM, Florian Fainelli <f.fainelli@gmail.com> wrote: > It may happen that a device needs to force applying a state, e.g: > because it only defines one state of pin states (default) but loses > power/register contents when entering low power modes. Add a > pinctrl_dev::flags bitmask to help describe future quirks and define > PINCTRL_FLG_FORCE_STATE as such a settable flag. > > Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> So if I understand correctly, the state is lost across suspend/resume, correct? Or are we even talking runtime PM runtime_suspend and runtime_resume here? > @@ -1197,9 +1197,21 @@ int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state) > { > struct pinctrl_setting *setting, *setting2; > struct pinctrl_state *old_state = p->state; > + bool force = false; > int ret; > > - if (p->state == state) > + if (p->state) { > + list_for_each_entry(setting, &p->state->settings, node) { > + if (setting->pctldev->flags & PINCTRL_FLG_FORCE_STATE) > + force = true; > + } > + } > + > + /* Some controllers may want to force this operation when they define > + * only one set of functions and lose power state, e.g: pinctrl-single > + * with its pinctrl-single,low-power-state-loss property. > + */ > + if (p->state == state && !force) > return 0; So the idea is we go and change the state even if we are in the right state already, I understand that much. But how is pinctrl_select_state() being called in the first place under these circumstances? If this comes from the resume() callback in .pm of the device driver, would not the same thing be achived if you just set some mock "sleep" state in suspend()? It could even have exactly the same settings as the "default" state, as long as it is another state, the register will be reprogrammed. See further include/linux/pinctrl/pinctrl-state.h Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
* Florian Fainelli <f.fainelli@gmail.com> [171102 23:18]: > It may happen that a device needs to force applying a state, e.g: > because it only defines one state of pin states (default) but loses > power/register contents when entering low power modes. Add a > pinctrl_dev::flags bitmask to help describe future quirks and define > PINCTRL_FLG_FORCE_STATE as such a settable flag. It makes sense to tag the existing state with the context loss information as otherwise we'll be duplicating the state in the pinctrl driver potentially for hundreds of pins. Maybe this patch description should clarify that it's the pinctrl device restoring the pin state, not the pinctrl consumer devices? So maybe just "a pinctrl device needs to force apply a state" instead of just device above? Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 11/29/2017 09:01 AM, Tony Lindgren wrote: > * Florian Fainelli <f.fainelli@gmail.com> [171102 23:18]: >> It may happen that a device needs to force applying a state, e.g: >> because it only defines one state of pin states (default) but loses >> power/register contents when entering low power modes. Add a >> pinctrl_dev::flags bitmask to help describe future quirks and define >> PINCTRL_FLG_FORCE_STATE as such a settable flag. > > It makes sense to tag the existing state with the context loss > information as otherwise we'll be duplicating the state in the > pinctrl driver potentially for hundreds of pins. > > Maybe this patch description should clarify that it's the > pinctrl device restoring the pin state, not the pinctrl > consumer devices? > > So maybe just "a pinctrl device needs to force apply a state" > instead of just device above? It's a bit more involved than that, the pinctrl consumer device might want to restore a particular state by calling pinctrl_select_state(), however, because of the (p->state == state)check, the pinctrl provider driver has no chance of making that call do the actual HW programming.
* Florian Fainelli <f.fainelli@gmail.com> [171129 17:37]: > On 11/29/2017 09:01 AM, Tony Lindgren wrote: > > * Florian Fainelli <f.fainelli@gmail.com> [171102 23:18]: > >> It may happen that a device needs to force applying a state, e.g: > >> because it only defines one state of pin states (default) but loses > >> power/register contents when entering low power modes. Add a > >> pinctrl_dev::flags bitmask to help describe future quirks and define > >> PINCTRL_FLG_FORCE_STATE as such a settable flag. > > > > It makes sense to tag the existing state with the context loss > > information as otherwise we'll be duplicating the state in the > > pinctrl driver potentially for hundreds of pins. > > > > Maybe this patch description should clarify that it's the > > pinctrl device restoring the pin state, not the pinctrl > > consumer devices? > > > > So maybe just "a pinctrl device needs to force apply a state" > > instead of just device above? > > It's a bit more involved than that, the pinctrl consumer device might > want to restore a particular state by calling pinctrl_select_state(), > however, because of the (p->state == state)check, the pinctrl provider > driver has no chance of making that call do the actual HW programming. Hmm but isn't it the pinctrl provider device losing context here? I think the restore of the pin state should somehow happen automatically by the pinctrl provider driver without a need for the pinctrl consumer drivers to do anything. Or what's the use case for pinctrl consumer driver wanting to store a pin? Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 11/29/2017 09:45 AM, Tony Lindgren wrote: > * Florian Fainelli <f.fainelli@gmail.com> [171129 17:37]: >> On 11/29/2017 09:01 AM, Tony Lindgren wrote: >>> * Florian Fainelli <f.fainelli@gmail.com> [171102 23:18]: >>>> It may happen that a device needs to force applying a state, e.g: >>>> because it only defines one state of pin states (default) but loses >>>> power/register contents when entering low power modes. Add a >>>> pinctrl_dev::flags bitmask to help describe future quirks and define >>>> PINCTRL_FLG_FORCE_STATE as such a settable flag. >>> >>> It makes sense to tag the existing state with the context loss >>> information as otherwise we'll be duplicating the state in the >>> pinctrl driver potentially for hundreds of pins. >>> >>> Maybe this patch description should clarify that it's the >>> pinctrl device restoring the pin state, not the pinctrl >>> consumer devices? >>> >>> So maybe just "a pinctrl device needs to force apply a state" >>> instead of just device above? >> >> It's a bit more involved than that, the pinctrl consumer device might >> want to restore a particular state by calling pinctrl_select_state(), >> however, because of the (p->state == state)check, the pinctrl provider >> driver has no chance of making that call do the actual HW programming. > > Hmm but isn't it the pinctrl provider device losing context here? It is the pinctrl provider indeed. > I think the restore of the pin state should somehow happen automatically > by the pinctrl provider driver without a need for the pinctrl consumer > drivers to do anything. Correct. > > Or what's the use case for pinctrl consumer driver wanting to store > a pin? I actually meant that a consumer driver could aalso call pinctrl_select_state() in one of its resume callback for instance, but if the pinctrl provider driver does nothing (or rather the core, on behalf of the provider), this would be an issue. This was not super clear, so I will stop using that example from now on :)
* Florian Fainelli <f.fainelli@gmail.com> [171129 18:17]: > On 11/29/2017 09:45 AM, Tony Lindgren wrote: > > * Florian Fainelli <f.fainelli@gmail.com> [171129 17:37]: > >> On 11/29/2017 09:01 AM, Tony Lindgren wrote: > >>> * Florian Fainelli <f.fainelli@gmail.com> [171102 23:18]: > >>>> It may happen that a device needs to force applying a state, e.g: > >>>> because it only defines one state of pin states (default) but loses > >>>> power/register contents when entering low power modes. Add a > >>>> pinctrl_dev::flags bitmask to help describe future quirks and define > >>>> PINCTRL_FLG_FORCE_STATE as such a settable flag. > >>> > >>> It makes sense to tag the existing state with the context loss > >>> information as otherwise we'll be duplicating the state in the > >>> pinctrl driver potentially for hundreds of pins. > >>> > >>> Maybe this patch description should clarify that it's the > >>> pinctrl device restoring the pin state, not the pinctrl > >>> consumer devices? > >>> > >>> So maybe just "a pinctrl device needs to force apply a state" > >>> instead of just device above? > >> > >> It's a bit more involved than that, the pinctrl consumer device might > >> want to restore a particular state by calling pinctrl_select_state(), > >> however, because of the (p->state == state)check, the pinctrl provider > >> driver has no chance of making that call do the actual HW programming. > > > > Hmm but isn't it the pinctrl provider device losing context here? > > It is the pinctrl provider indeed. > > > I think the restore of the pin state should somehow happen automatically > > by the pinctrl provider driver without a need for the pinctrl consumer > > drivers to do anything. > > Correct. OK thanks for confirming that. > > Or what's the use case for pinctrl consumer driver wanting to store > > a pin? > > I actually meant that a consumer driver could aalso call > pinctrl_select_state() in one of its resume callback for instance, but > if the pinctrl provider driver does nothing (or rather the core, on > behalf of the provider), this would be an issue. This was not super > clear, so I will stop using that example from now on :) OK yeah that's probably where the confusion comes from :) Tony -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c index 4c8d5b23e4d0..c91359d48aa1 100644 --- a/drivers/pinctrl/core.c +++ b/drivers/pinctrl/core.c @@ -1197,9 +1197,21 @@ int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state) { struct pinctrl_setting *setting, *setting2; struct pinctrl_state *old_state = p->state; + bool force = false; int ret; - if (p->state == state) + if (p->state) { + list_for_each_entry(setting, &p->state->settings, node) { + if (setting->pctldev->flags & PINCTRL_FLG_FORCE_STATE) + force = true; + } + } + + /* Some controllers may want to force this operation when they define + * only one set of functions and lose power state, e.g: pinctrl-single + * with its pinctrl-single,low-power-state-loss property. + */ + if (p->state == state && !force) return 0; if (p->state) { diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h index 8cf2eba17c8c..8f900e152295 100644 --- a/drivers/pinctrl/core.h +++ b/drivers/pinctrl/core.h @@ -39,6 +39,7 @@ struct pinctrl_gpio_range; * @hog_sleep: sleep state for pins hogged by this device * @mutex: mutex taken on each pin controller specific action * @device_root: debugfs root for this device + * @flags: feature/quirk flags */ struct pinctrl_dev { struct list_head node; @@ -63,8 +64,11 @@ struct pinctrl_dev { #ifdef CONFIG_DEBUG_FS struct dentry *device_root; #endif + unsigned long flags; }; +#define PINCTRL_FLG_FORCE_STATE (1 << 0) + /** * struct pinctrl - per-device pin control state holder * @node: global list node
It may happen that a device needs to force applying a state, e.g: because it only defines one state of pin states (default) but loses power/register contents when entering low power modes. Add a pinctrl_dev::flags bitmask to help describe future quirks and define PINCTRL_FLG_FORCE_STATE as such a settable flag. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> --- drivers/pinctrl/core.c | 14 +++++++++++++- drivers/pinctrl/core.h | 4 ++++ 2 files changed, 17 insertions(+), 1 deletion(-)