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Message-ID: <7hv7z9ahlw.fsf@baylibre.com> Date: Thu, 05 Sep 2024 14:57:47 -0700 From: Kevin Hilman <khilman@...libre.com> To: Ulf Hansson <ulf.hansson@...aro.org> Cc: linux-pm@...r.kernel.org, Nishanth Menon <nm@...com>, Vibhore Vardhan <vibhore@...com>, Dhruva Gole <d-gole@...com>, Akashdeep Kaur <a-kaur@...com>, Sebin Francis <sebin.francis@...com>, Markus Schneider-Pargmann <msp@...libre.com>, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2 1/3] pmdomain: ti_sci: add per-device latency constraint management Ulf Hansson <ulf.hansson@...aro.org> writes: > On Tue, 20 Aug 2024 at 02:00, Kevin Hilman <khilman@...libre.com> wrote: >> >> For each device in a TI SCI PM domain, check whether the device has >> any resume latency constraints set via per-device PM QoS. If >> constraints are set, send them to DM via the new SCI constraints API. >> >> Checking for constraints happen for each device before system-wide >> suspend (via ->suspend() hook.) >> >> An important detail here is that the PM domain driver inserts itself >> into the path of both the ->suspend() and ->resume() hook path >> of *all* devices in the PM domain. This allows generic PM domain code >> to handle the constraint management and communication with TI SCI. >> >> Further, this allows device drivers to use existing PM QoS APIs to >> add/update constraints. >> >> DM firmware clears constraints during its resume, so Linux has >> to check/update/send constraints each time system suspends. >> >> Co-developed-by: Vibhore Vardhan <vibhore@...com> >> Signed-off-by: Vibhore Vardhan <vibhore@...com> >> Signed-off-by: Kevin Hilman <khilman@...libre.com> >> Signed-off-by: Dhruva Gole <d-gole@...com> >> --- >> drivers/pmdomain/ti/ti_sci_pm_domains.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 48 insertions(+) >> >> diff --git a/drivers/pmdomain/ti/ti_sci_pm_domains.c b/drivers/pmdomain/ti/ti_sci_pm_domains.c >> index 1510d5ddae3d..963272fa387b 100644 >> --- a/drivers/pmdomain/ti/ti_sci_pm_domains.c >> +++ b/drivers/pmdomain/ti/ti_sci_pm_domains.c >> @@ -13,6 +13,8 @@ >> #include <linux/platform_device.h> >> #include <linux/pm_domain.h> >> #include <linux/slab.h> >> +#include <linux/pm_qos.h> >> +#include <linux/pm_runtime.h> >> #include <linux/soc/ti/ti_sci_protocol.h> >> #include <dt-bindings/soc/ti,sci_pm_domain.h> >> >> @@ -51,6 +53,29 @@ struct ti_sci_pm_domain { >> >> #define genpd_to_ti_sci_pd(gpd) container_of(gpd, struct ti_sci_pm_domain, pd) >> >> +static inline bool ti_sci_pd_is_valid_constraint(s32 val) >> +{ >> + return val != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT; >> +} > > Should we perhaps add a generic helper function for this? Seems like a > similar check is done at other places in the kernel too. Maybe, but I don't see a lot of this same usage under drivers/*. But I'll have a closer look for a follow-up patch that might be able to make a common helper for this. >> + >> +static int ti_sci_pd_set_lat_constraint(struct device *dev, s32 val) >> +{ > > Looks like you may want to turn this into a static void rather than > static int. At least the caller, below, doesn't care about the return > value. Yup, OK. >> + struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain); >> + struct ti_sci_pm_domain *pd = genpd_to_ti_sci_pd(genpd); >> + const struct ti_sci_handle *ti_sci = pd->parent->ti_sci; >> + int ret; >> + >> + ret = ti_sci->ops.pm_ops.set_latency_constraint(ti_sci, val, TISCI_MSG_CONSTRAINT_SET); >> + if (ret) >> + dev_err(dev, "ti_sci_pd: set latency constraint failed: ret=%d\n", >> + ret); >> + else >> + dev_dbg(dev, "ti_sci_pd: ID:%d set latency constraint %d\n", >> + pd->idx, val); >> + >> + return ret; >> +} >> + >> /* >> * ti_sci_pd_power_off(): genpd power down hook >> * @domain: pointer to the powerdomain to power off >> @@ -79,6 +104,22 @@ static int ti_sci_pd_power_on(struct generic_pm_domain *domain) >> return ti_sci->ops.dev_ops.get_device(ti_sci, pd->idx); >> } >> >> +static int ti_sci_pd_suspend(struct device *dev) >> +{ >> + int ret; >> + s32 val; >> + >> + ret = pm_generic_suspend(dev); >> + if (ret) >> + return ret; >> + >> + val = dev_pm_qos_read_value(dev, DEV_PM_QOS_RESUME_LATENCY); >> + if (ti_sci_pd_is_valid_constraint(val)) >> + ti_sci_pd_set_lat_constraint(dev, val); >> + >> + return 0; >> +} >> + >> /* >> * ti_sci_pd_xlate(): translation service for TI SCI genpds >> * @genpdspec: DT identification data for the genpd >> @@ -188,6 +229,13 @@ static int ti_sci_pm_domain_probe(struct platform_device *pdev) >> pd->pd.power_on = ti_sci_pd_power_on; >> pd->idx = args.args[0]; >> pd->parent = pd_provider; >> + /* >> + * If SCI constraint functions are present, then firmware >> + * supports the constraints API. >> + */ >> + if (pd_provider->ti_sci->ops.pm_ops.set_device_constraint && >> + pd_provider->ti_sci->ops.pm_ops.set_latency_constraint) >> + pd->pd.domain.ops.suspend = ti_sci_pd_suspend; >> >> pm_genpd_init(&pd->pd, NULL, true); >> >> >> -- >> 2.46.0 >> > > Other than the minor things above, this looks good to me. Thanks for the review! Will spin a v3 shortly. Kevin
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