| Message ID | 1592792699-24638-3-git-send-email-yoshihiro.shimoda.uh@renesas.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | treewide: fix _mmc_suspend() on PSCI | expand |
On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> wrote: > > If pm_suspend_via_firmware() returns true, the system will be able > to cut both vcc and vccq in the suspend. So, call > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > because the mmc_select_voltage() checks the caps when attaches > a mmc/sd. > > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> > --- > drivers/mmc/core/mmc.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c > index 4203303..81941fd 100644 > --- a/drivers/mmc/core/mmc.c > +++ b/drivers/mmc/core/mmc.c > @@ -11,6 +11,7 @@ > #include <linux/of.h> > #include <linux/slab.h> > #include <linux/stat.h> > +#include <linux/suspend.h> > #include <linux/pm_runtime.h> > > #include <linux/mmc/host.h> > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > goto out; > > if (mmc_can_poweroff_notify(host->card) && > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > + pm_suspend_via_firmware())) Sorry, but this doesn't work. Even if PSCI is a generic FW interface, it doesn't mean that all PSCI implementations will cut the vcc and vccq for the MMC card at system suspend. Instead, you need to decide this based on some specific DT property. Perhaps in conjunction with using pm_suspend_via_firmware(). > err = mmc_poweroff_notify(host->card, notify_type); > else if (mmc_can_sleep(host->card)) > err = mmc_sleep(host); > -- > 2.7.4 > Kind regards Uffe
Hi Ulf, On Wed, Jun 24, 2020 at 12:06 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda > <yoshihiro.shimoda.uh@renesas.com> wrote: > > If pm_suspend_via_firmware() returns true, the system will be able > > to cut both vcc and vccq in the suspend. So, call > > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > > because the mmc_select_voltage() checks the caps when attaches > > a mmc/sd. > > --- a/drivers/mmc/core/mmc.c > > +++ b/drivers/mmc/core/mmc.c > > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > > goto out; > > > > if (mmc_can_poweroff_notify(host->card) && > > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > > + pm_suspend_via_firmware())) > > Sorry, but this doesn't work. > > Even if PSCI is a generic FW interface, it doesn't mean that all PSCI > implementations will cut the vcc and vccq for the MMC card at system > suspend. Indeed, there's nothing guaranteed here. Nor documented how it should behave. Basically the firmware is free to power off the SoC. Or not do that. "If firmware is involved, all odds are off". > Instead, you need to decide this based on some specific DT property. > Perhaps in conjunction with using pm_suspend_via_firmware(). Last time I was involved in a discussion about this, the PSCI people didn't want to add any properties describing particular PSCI behavior... "If firmware is involved, all odds are off". So the only safe thing to do is to expect the worst, and prepare for it... Gr{oetje,eeting}s, Geert
Hi Ulf, Geert, > From: Geert Uytterhoeven, Sent: Wednesday, June 24, 2020 8:13 PM > > Hi Ulf, > > On Wed, Jun 24, 2020 at 12:06 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > If pm_suspend_via_firmware() returns true, the system will be able > > > to cut both vcc and vccq in the suspend. So, call > > > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > > > > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > > > because the mmc_select_voltage() checks the caps when attaches > > > a mmc/sd. > > > > --- a/drivers/mmc/core/mmc.c > > > +++ b/drivers/mmc/core/mmc.c > > > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > > > goto out; > > > > > > if (mmc_can_poweroff_notify(host->card) && > > > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > > > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > > > + pm_suspend_via_firmware())) > > > > Sorry, but this doesn't work. > > > > Even if PSCI is a generic FW interface, it doesn't mean that all PSCI > > implementations will cut the vcc and vccq for the MMC card at system > > suspend. > > Indeed, there's nothing guaranteed here. Nor documented how it should > behave. Basically the firmware is free to power off the SoC. Or not do that. > "If firmware is involved, all odds are off". I thought we could be guaranteed. But, I understood we could not be guaranteed... > > Instead, you need to decide this based on some specific DT property. > > Perhaps in conjunction with using pm_suspend_via_firmware(). > > Last time I was involved in a discussion about this, the PSCI people > didn't want to add any properties describing particular PSCI behavior... > "If firmware is involved, all odds are off". > > So the only safe thing to do is to expect the worst, and prepare for it... A headache point is an eMMC device consumes much power if that the system doesn't cut the vcc and vccq and doesn’t enter the sleep mode. In other words, in power consumption point of view, this patch will cause a regression in such a case... By the way, about adding specific DT property, the regulator can have regulator-off-in-suspend property in regulator-state-mem subnode. For now, we doesn't seem to get the property from a regulator consumer though. So, I'll try to add an API of regulator for it. Best regards, Yoshihiro Shimoda > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds
Hi Shimoda-san, CC broonie On Thu, Jun 25, 2020 at 8:31 AM Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> wrote: > > From: Geert Uytterhoeven, Sent: Wednesday, June 24, 2020 8:13 PM > > On Wed, Jun 24, 2020 at 12:06 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > > On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > If pm_suspend_via_firmware() returns true, the system will be able > > > > to cut both vcc and vccq in the suspend. So, call > > > > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > > > > > > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > > > > because the mmc_select_voltage() checks the caps when attaches > > > > a mmc/sd. > > > > > > --- a/drivers/mmc/core/mmc.c > > > > +++ b/drivers/mmc/core/mmc.c > > > > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > > > > goto out; > > > > > > > > if (mmc_can_poweroff_notify(host->card) && > > > > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > > > > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > > > > + pm_suspend_via_firmware())) > > > > > > Sorry, but this doesn't work. > > > > > > Even if PSCI is a generic FW interface, it doesn't mean that all PSCI > > > implementations will cut the vcc and vccq for the MMC card at system > > > suspend. > > > > Indeed, there's nothing guaranteed here. Nor documented how it should > > behave. Basically the firmware is free to power off the SoC. Or not do that. > > "If firmware is involved, all odds are off". > > I thought we could be guaranteed. But, I understood we could not be guaranteed... > > > > Instead, you need to decide this based on some specific DT property. > > > Perhaps in conjunction with using pm_suspend_via_firmware(). > > > > Last time I was involved in a discussion about this, the PSCI people > > didn't want to add any properties describing particular PSCI behavior... > > "If firmware is involved, all odds are off". > > > > So the only safe thing to do is to expect the worst, and prepare for it... > > A headache point is an eMMC device consumes much power if that the system > doesn't cut the vcc and vccq and doesn’t enter the sleep mode. > In other words, in power consumption point of view, this patch will > cause a regression in such a case... Indeed. > By the way, about adding specific DT property, the regulator can have > regulator-off-in-suspend property in regulator-state-mem subnode. > For now, we doesn't seem to get the property from a regulator consumer though. > So, I'll try to add an API of regulator for it. Oh right, the eMMC is described in DT as being connected to two regulators. Note that the semantics of regulator-off-in-suspend are that the regulator should be disabled (by the regulator core) during suspend, not that the regulator is disabled during suspend by a third party. No idea if that will work with a fixed-regulator without GPIO control, but of course you can try. Gr{oetje,eeting}s, Geert
+ Rob On Thu, 25 Jun 2020 at 11:26, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > Hi Shimoda-san, > > CC broonie > > On Thu, Jun 25, 2020 at 8:31 AM Yoshihiro Shimoda > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > From: Geert Uytterhoeven, Sent: Wednesday, June 24, 2020 8:13 PM > > > On Wed, Jun 24, 2020 at 12:06 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > > > On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda > > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > If pm_suspend_via_firmware() returns true, the system will be able > > > > > to cut both vcc and vccq in the suspend. So, call > > > > > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > > > > > > > > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > > > > > because the mmc_select_voltage() checks the caps when attaches > > > > > a mmc/sd. > > > > > > > > --- a/drivers/mmc/core/mmc.c > > > > > +++ b/drivers/mmc/core/mmc.c > > > > > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > > > > > goto out; > > > > > > > > > > if (mmc_can_poweroff_notify(host->card) && > > > > > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > > > > > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > > > > > + pm_suspend_via_firmware())) > > > > > > > > Sorry, but this doesn't work. > > > > > > > > Even if PSCI is a generic FW interface, it doesn't mean that all PSCI > > > > implementations will cut the vcc and vccq for the MMC card at system > > > > suspend. > > > > > > Indeed, there's nothing guaranteed here. Nor documented how it should > > > behave. Basically the firmware is free to power off the SoC. Or not do that. > > > "If firmware is involved, all odds are off". > > > > I thought we could be guaranteed. But, I understood we could not be guaranteed... > > > > > > Instead, you need to decide this based on some specific DT property. > > > > Perhaps in conjunction with using pm_suspend_via_firmware(). > > > > > > Last time I was involved in a discussion about this, the PSCI people > > > didn't want to add any properties describing particular PSCI behavior... > > > "If firmware is involved, all odds are off". > > > > > > So the only safe thing to do is to expect the worst, and prepare for it... > > > > A headache point is an eMMC device consumes much power if that the system > > doesn't cut the vcc and vccq and doesn’t enter the sleep mode. > > In other words, in power consumption point of view, this patch will > > cause a regression in such a case... > > Indeed. > > > By the way, about adding specific DT property, the regulator can have > > regulator-off-in-suspend property in regulator-state-mem subnode. > > For now, we doesn't seem to get the property from a regulator consumer though. > > So, I'll try to add an API of regulator for it. > > Oh right, the eMMC is described in DT as being connected to two > regulators. > Note that the semantics of regulator-off-in-suspend are that the > regulator should be disabled (by the regulator core) during suspend, not > that the regulator is disabled during suspend by a third party. > No idea if that will work with a fixed-regulator without GPIO control, > but of course you can try. For mmc we already have a DT property, "full-pwr-cycle". Which tells whether the host is able to completely power-cycle the card (some host's manage power internally). However, maybe the proper thing here would be to add a property of regulator instead. If that doesn't make sense, I am also open to add a new MMC property, "full-pwr-cycle-in-suspend". Kind regards Uffe
Hi Ulf, > From: Ulf Hansson, Sent: Friday, June 26, 2020 8:03 PM > > + Rob > > On Thu, 25 Jun 2020 at 11:26, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > > > Hi Shimoda-san, > > > > CC broonie > > > > On Thu, Jun 25, 2020 at 8:31 AM Yoshihiro Shimoda > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > From: Geert Uytterhoeven, Sent: Wednesday, June 24, 2020 8:13 PM > > > > On Wed, Jun 24, 2020 at 12:06 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > > > > On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda > > > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > > If pm_suspend_via_firmware() returns true, the system will be able > > > > > > to cut both vcc and vccq in the suspend. So, call > > > > > > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > > > > > > > > > > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > > > > > > because the mmc_select_voltage() checks the caps when attaches > > > > > > a mmc/sd. > > > > > > > > > > --- a/drivers/mmc/core/mmc.c > > > > > > +++ b/drivers/mmc/core/mmc.c > > > > > > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > > > > > > goto out; > > > > > > > > > > > > if (mmc_can_poweroff_notify(host->card) && > > > > > > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > > > > > > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > > > > > > + pm_suspend_via_firmware())) > > > > > > > > > > Sorry, but this doesn't work. > > > > > > > > > > Even if PSCI is a generic FW interface, it doesn't mean that all PSCI > > > > > implementations will cut the vcc and vccq for the MMC card at system > > > > > suspend. > > > > > > > > Indeed, there's nothing guaranteed here. Nor documented how it should > > > > behave. Basically the firmware is free to power off the SoC. Or not do that. > > > > "If firmware is involved, all odds are off". > > > > > > I thought we could be guaranteed. But, I understood we could not be guaranteed... > > > > > > > > Instead, you need to decide this based on some specific DT property. > > > > > Perhaps in conjunction with using pm_suspend_via_firmware(). > > > > > > > > Last time I was involved in a discussion about this, the PSCI people > > > > didn't want to add any properties describing particular PSCI behavior... > > > > "If firmware is involved, all odds are off". > > > > > > > > So the only safe thing to do is to expect the worst, and prepare for it... > > > > > > A headache point is an eMMC device consumes much power if that the system > > > doesn't cut the vcc and vccq and doesn’t enter the sleep mode. > > > In other words, in power consumption point of view, this patch will > > > cause a regression in such a case... > > > > Indeed. > > > > > By the way, about adding specific DT property, the regulator can have > > > regulator-off-in-suspend property in regulator-state-mem subnode. > > > For now, we doesn't seem to get the property from a regulator consumer though. > > > So, I'll try to add an API of regulator for it. > > > > Oh right, the eMMC is described in DT as being connected to two > > regulators. > > Note that the semantics of regulator-off-in-suspend are that the > > regulator should be disabled (by the regulator core) during suspend, not > > that the regulator is disabled during suspend by a third party. > > No idea if that will work with a fixed-regulator without GPIO control, > > but of course you can try. As other email thread of this trial as v4, I could not get approval [1]. [1] https://lore.kernel.org/linux-renesas-soc/CAMuHMdX93Q9WhKLqv_wNPzArbc68NcbVN8jJ9MDKxAcicpBQ5Q@mail.gmail.com/T/#m70883cc5de4fa7fca50118dad743c836d5e3b451 > For mmc we already have a DT property, "full-pwr-cycle". Which tells > whether the host is able to completely power-cycle the card (some > host's manage power internally). > > However, maybe the proper thing here would be to add a property of > regulator instead. My v4 patch was using a regulator property. But since I could not get approval, we could not use this way, I think. > If that doesn't make sense, I am also open to add a > new MMC property, "full-pwr-cycle-in-suspend". I thought this way was better. However, I'm wondering if adding such a new MMC property to issue Power Off Notification in mmc_suspend() is really better than the current implementation. This is because we don't have any completely solutions now: - Depend on board configuration (The board doesn't have "full-pwr-cycle"). - Depend on firmware on board [2]. So, even if adding a new MMC property, it cannot sync the firmware condition. In fact, this is possible to cause regression in power consumption point of view [3]. - My environment (PSCI which is one of firmware) doesn't support any ability to sync between the firmware and OS for now [4]. But, what do you think? [2] https://lore.kernel.org/linux-renesas-soc/1592792699-24638-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/T/#mde38d5866b7f3edc9a2ed105ac06b4fda4c3e99e [3] https://lore.kernel.org/linux-renesas-soc/1592792699-24638-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/T/#mf8e7abdf135586ba0b70a1c235410a6f94c6007d [4] https://lore.kernel.org/linux-renesas-soc/CAMuHMdX93Q9WhKLqv_wNPzArbc68NcbVN8jJ9MDKxAcicpBQ5Q@mail.gmail.com/T/#m442a2ce972cfdb3ff33637c120c8d096e4d07af8 Best regards, Yoshihiro Shimoda > Kind regards > Uffe
On Thu, 2 Jul 2020 at 14:37, Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> wrote: > > Hi Ulf, > > > From: Ulf Hansson, Sent: Friday, June 26, 2020 8:03 PM > > > > + Rob > > > > On Thu, 25 Jun 2020 at 11:26, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > > > > > Hi Shimoda-san, > > > > > > CC broonie > > > > > > On Thu, Jun 25, 2020 at 8:31 AM Yoshihiro Shimoda > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > From: Geert Uytterhoeven, Sent: Wednesday, June 24, 2020 8:13 PM > > > > > On Wed, Jun 24, 2020 at 12:06 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > > > > > On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda > > > > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > > > If pm_suspend_via_firmware() returns true, the system will be able > > > > > > > to cut both vcc and vccq in the suspend. So, call > > > > > > > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > > > > > > > > > > > > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > > > > > > > because the mmc_select_voltage() checks the caps when attaches > > > > > > > a mmc/sd. > > > > > > > > > > > > --- a/drivers/mmc/core/mmc.c > > > > > > > +++ b/drivers/mmc/core/mmc.c > > > > > > > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > > > > > > > goto out; > > > > > > > > > > > > > > if (mmc_can_poweroff_notify(host->card) && > > > > > > > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > > > > > > > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > > > > > > > + pm_suspend_via_firmware())) > > > > > > > > > > > > Sorry, but this doesn't work. > > > > > > > > > > > > Even if PSCI is a generic FW interface, it doesn't mean that all PSCI > > > > > > implementations will cut the vcc and vccq for the MMC card at system > > > > > > suspend. > > > > > > > > > > Indeed, there's nothing guaranteed here. Nor documented how it should > > > > > behave. Basically the firmware is free to power off the SoC. Or not do that. > > > > > "If firmware is involved, all odds are off". > > > > > > > > I thought we could be guaranteed. But, I understood we could not be guaranteed... > > > > > > > > > > Instead, you need to decide this based on some specific DT property. > > > > > > Perhaps in conjunction with using pm_suspend_via_firmware(). > > > > > > > > > > Last time I was involved in a discussion about this, the PSCI people > > > > > didn't want to add any properties describing particular PSCI behavior... > > > > > "If firmware is involved, all odds are off". > > > > > > > > > > So the only safe thing to do is to expect the worst, and prepare for it... > > > > > > > > A headache point is an eMMC device consumes much power if that the system > > > > doesn't cut the vcc and vccq and doesn’t enter the sleep mode. > > > > In other words, in power consumption point of view, this patch will > > > > cause a regression in such a case... > > > > > > Indeed. > > > > > > > By the way, about adding specific DT property, the regulator can have > > > > regulator-off-in-suspend property in regulator-state-mem subnode. > > > > For now, we doesn't seem to get the property from a regulator consumer though. > > > > So, I'll try to add an API of regulator for it. > > > > > > Oh right, the eMMC is described in DT as being connected to two > > > regulators. > > > Note that the semantics of regulator-off-in-suspend are that the > > > regulator should be disabled (by the regulator core) during suspend, not > > > that the regulator is disabled during suspend by a third party. > > > No idea if that will work with a fixed-regulator without GPIO control, > > > but of course you can try. > > As other email thread of this trial as v4, I could not get approval [1]. > > [1] > https://lore.kernel.org/linux-renesas-soc/CAMuHMdX93Q9WhKLqv_wNPzArbc68NcbVN8jJ9MDKxAcicpBQ5Q@mail.gmail.com/T/#m70883cc5de4fa7fca50118dad743c836d5e3b451 > > > For mmc we already have a DT property, "full-pwr-cycle". Which tells > > whether the host is able to completely power-cycle the card (some > > host's manage power internally). > > > > However, maybe the proper thing here would be to add a property of > > regulator instead. > > My v4 patch was using a regulator property. But since I could not get > approval, we could not use this way, I think. > > > If that doesn't make sense, I am also open to add a > > new MMC property, "full-pwr-cycle-in-suspend". > > I thought this way was better. However, I'm wondering if adding such a new MMC > property to issue Power Off Notification in mmc_suspend() is really better > than the current implementation. This is because we don't have any completely > solutions now: > - Depend on board configuration (The board doesn't have "full-pwr-cycle"). > - Depend on firmware on board [2]. So, even if adding a new MMC property, > it cannot sync the firmware condition. In fact, this is possible to > cause regression in power consumption point of view [3]. This is a generic problem with FWs. I guess one could try to update the DTB using DT overlays, in case some FW version changes. > - My environment (PSCI which is one of firmware) doesn't support > any ability to sync between the firmware and OS for now [4]. Yes, I see. It seems like Geert has tried different approaches to convince PSCI folkz, to find a solution for this, but it seems like none have make it yet. > > But, what do you think? From the mmc DT property point of view, I am fine adding a "full-pwr-cycle-in-suspend" - and then also update the mmc core's behavior to use the eMMC power-off-notify command at system suspend. However, I don't have a strong opinion, as the current solution with the eMMC sleep command also seems to work. My main concern with the current approach though, is not about wasting energy, but rather that we are not doing a graceful shutdown of the eMMC device. Instead we just cut VCCQ while the eMMC is "sleeping", which in worst case could lead to internal data corruptions, but also increased re-initialization time at system suspend. > > [2] > https://lore.kernel.org/linux-renesas-soc/1592792699-24638-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/T/#mde38d5866b7f3edc9a2ed105ac06b4fda4c3e99e > > [3] > https://lore.kernel.org/linux-renesas-soc/1592792699-24638-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/T/#mf8e7abdf135586ba0b70a1c235410a6f94c6007d > > [4] > https://lore.kernel.org/linux-renesas-soc/CAMuHMdX93Q9WhKLqv_wNPzArbc68NcbVN8jJ9MDKxAcicpBQ5Q@mail.gmail.com/T/#m442a2ce972cfdb3ff33637c120c8d096e4d07af8 > Kind regards Uffe
Hi Ulf, > From: Ulf Hansson, Sent: Monday, July 6, 2020 10:11 PM > > On Thu, 2 Jul 2020 at 14:37, Yoshihiro Shimoda > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > Hi Ulf, > > > > > From: Ulf Hansson, Sent: Friday, June 26, 2020 8:03 PM > > > > > > + Rob > > > > > > On Thu, 25 Jun 2020 at 11:26, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > > > > > > > Hi Shimoda-san, > > > > > > > > CC broonie > > > > > > > > On Thu, Jun 25, 2020 at 8:31 AM Yoshihiro Shimoda > > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > > From: Geert Uytterhoeven, Sent: Wednesday, June 24, 2020 8:13 PM > > > > > > On Wed, Jun 24, 2020 at 12:06 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > > > > > > On Mon, 22 Jun 2020 at 04:25, Yoshihiro Shimoda > > > > > > > <yoshihiro.shimoda.uh@renesas.com> wrote: > > > > > > > > If pm_suspend_via_firmware() returns true, the system will be able > > > > > > > > to cut both vcc and vccq in the suspend. So, call > > > > > > > > mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. > > > > > > > > > > > > > > > > Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps > > > > > > > > because the mmc_select_voltage() checks the caps when attaches > > > > > > > > a mmc/sd. > > > > > > > > > > > > > > --- a/drivers/mmc/core/mmc.c > > > > > > > > +++ b/drivers/mmc/core/mmc.c > > > > > > > > @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) > > > > > > > > goto out; > > > > > > > > > > > > > > > > if (mmc_can_poweroff_notify(host->card) && > > > > > > > > - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) > > > > > > > > + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || > > > > > > > > + pm_suspend_via_firmware())) > > > > > > > > > > > > > > Sorry, but this doesn't work. > > > > > > > > > > > > > > Even if PSCI is a generic FW interface, it doesn't mean that all PSCI > > > > > > > implementations will cut the vcc and vccq for the MMC card at system > > > > > > > suspend. > > > > > > > > > > > > Indeed, there's nothing guaranteed here. Nor documented how it should > > > > > > behave. Basically the firmware is free to power off the SoC. Or not do that. > > > > > > "If firmware is involved, all odds are off". > > > > > > > > > > I thought we could be guaranteed. But, I understood we could not be guaranteed... > > > > > > > > > > > > Instead, you need to decide this based on some specific DT property. > > > > > > > Perhaps in conjunction with using pm_suspend_via_firmware(). > > > > > > > > > > > > Last time I was involved in a discussion about this, the PSCI people > > > > > > didn't want to add any properties describing particular PSCI behavior... > > > > > > "If firmware is involved, all odds are off". > > > > > > > > > > > > So the only safe thing to do is to expect the worst, and prepare for it... > > > > > > > > > > A headache point is an eMMC device consumes much power if that the system > > > > > doesn't cut the vcc and vccq and doesn’t enter the sleep mode. > > > > > In other words, in power consumption point of view, this patch will > > > > > cause a regression in such a case... > > > > > > > > Indeed. > > > > > > > > > By the way, about adding specific DT property, the regulator can have > > > > > regulator-off-in-suspend property in regulator-state-mem subnode. > > > > > For now, we doesn't seem to get the property from a regulator consumer though. > > > > > So, I'll try to add an API of regulator for it. > > > > > > > > Oh right, the eMMC is described in DT as being connected to two > > > > regulators. > > > > Note that the semantics of regulator-off-in-suspend are that the > > > > regulator should be disabled (by the regulator core) during suspend, not > > > > that the regulator is disabled during suspend by a third party. > > > > No idea if that will work with a fixed-regulator without GPIO control, > > > > but of course you can try. > > > > As other email thread of this trial as v4, I could not get approval [1]. > > > > [1] > > > https://lore.kernel.org/linux-renesas-soc/CAMuHMdX93Q9WhKLqv_wNPzArbc68NcbVN8jJ9MDKxAcicpBQ5Q@mail.gmail.com/T/#m708 > 83cc5de4fa7fca50118dad743c836d5e3b451 > > > > > For mmc we already have a DT property, "full-pwr-cycle". Which tells > > > whether the host is able to completely power-cycle the card (some > > > host's manage power internally). > > > > > > However, maybe the proper thing here would be to add a property of > > > regulator instead. > > > > My v4 patch was using a regulator property. But since I could not get > > approval, we could not use this way, I think. > > > > > If that doesn't make sense, I am also open to add a > > > new MMC property, "full-pwr-cycle-in-suspend". > > > > I thought this way was better. However, I'm wondering if adding such a new MMC > > property to issue Power Off Notification in mmc_suspend() is really better > > than the current implementation. This is because we don't have any completely > > solutions now: > > - Depend on board configuration (The board doesn't have "full-pwr-cycle"). > > - Depend on firmware on board [2]. So, even if adding a new MMC property, > > it cannot sync the firmware condition. In fact, this is possible to > > cause regression in power consumption point of view [3]. > > This is a generic problem with FWs. > > I guess one could try to update the DTB using DT overlays, in case > some FW version changes. It's interesting. > > - My environment (PSCI which is one of firmware) doesn't support > > any ability to sync between the firmware and OS for now [4]. > > Yes, I see. > > It seems like Geert has tried different approaches to convince PSCI > folkz, to find a solution for this, but it seems like none have make > it yet. > > > > > But, what do you think? > > From the mmc DT property point of view, I am fine adding a > "full-pwr-cycle-in-suspend" - and then also update the mmc core's > behavior to use the eMMC power-off-notify command at system suspend. > > However, I don't have a strong opinion, as the current solution with > the eMMC sleep command also seems to work. > > My main concern with the current approach though, is not about wasting > energy, but rather that we are not doing a graceful shutdown of the > eMMC device. Instead we just cut VCCQ while the eMMC is "sleeping", > which in worst case could lead to internal data corruptions, but also > increased re-initialization time at system suspend. Thank you very much for your comments! I understood your main concern. So, I'm thinking adding a new MMC property "full-pwr-cycle-in-suspend" is useful now. After that, user could choose a graceful shutdown instead of "sleeping" to avoid internal data corruptions in worst case at system suspend. I'll submit such a patch. Best regards, Yoshihiro Shimoda > > > > [2] > > > https://lore.kernel.org/linux-renesas-soc/1592792699-24638-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/T/#mde3 > 8d5866b7f3edc9a2ed105ac06b4fda4c3e99e > > > > [3] > > > https://lore.kernel.org/linux-renesas-soc/1592792699-24638-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/T/#mf8e > 7abdf135586ba0b70a1c235410a6f94c6007d > > > > [4] > > > https://lore.kernel.org/linux-renesas-soc/CAMuHMdX93Q9WhKLqv_wNPzArbc68NcbVN8jJ9MDKxAcicpBQ5Q@mail.gmail.com/T/#m442 > a2ce972cfdb3ff33637c120c8d096e4d07af8 > > > > Kind regards > Uffe
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 4203303..81941fd 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -11,6 +11,7 @@ #include <linux/of.h> #include <linux/slab.h> #include <linux/stat.h> +#include <linux/suspend.h> #include <linux/pm_runtime.h> #include <linux/mmc/host.h> @@ -2038,7 +2039,8 @@ static int _mmc_suspend(struct mmc_host *host, bool is_suspend) goto out; if (mmc_can_poweroff_notify(host->card) && - ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend)) + ((host->caps2 & MMC_CAP2_FULL_PWR_CYCLE) || !is_suspend || + pm_suspend_via_firmware())) err = mmc_poweroff_notify(host->card, notify_type); else if (mmc_can_sleep(host->card)) err = mmc_sleep(host);
If pm_suspend_via_firmware() returns true, the system will be able to cut both vcc and vccq in the suspend. So, call mmc_poweroff_nofity() if pm_suspend_via_firmware() returns true. Note that we should not update the MMC_CAP2_FULL_PWR_CYCLE caps because the mmc_select_voltage() checks the caps when attaches a mmc/sd. Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> --- drivers/mmc/core/mmc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)