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Tue, 06 Aug 2024 15:53:50 -0700 (PDT) Received: from localhost ([71.212.170.185]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7106ec49b87sm7425888b3a.81.2024.08.06.15.53.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Aug 2024 15:53:49 -0700 (PDT) From: Kevin Hilman To: Markus Schneider-Pargmann Cc: Ulf Hansson , Nishanth Menon , Vibhore Vardhan , Dhruva Gole , Akashdeep Kaur , Sebin Francis , linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, 20240801195422.2296347-1-msp@baylibre.com Subject: Re: [PATCH 1/3] pmdomain: ti_sci: add per-device latency constraint management In-Reply-To: References: <20240805-lpm-v6-10-constraints-pmdomain-v1-0-d186b68ded4c@baylibre.com> <20240805-lpm-v6-10-constraints-pmdomain-v1-1-d186b68ded4c@baylibre.com> Date: Tue, 06 Aug 2024 15:53:49 -0700 Message-ID: <7hbk25w9du.fsf@baylibre.com> MIME-Version: 1.0 Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240806_155352_055245_7FF00DC0 X-CRM114-Status: GOOD ( 32.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Markus Schneider-Pargmann writes: > Hi Kevin, > > On Mon, Aug 05, 2024 at 04:38:39PM GMT, Kevin Hilman 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: >> >> 1) before SCI PM domain power off (->power_off() hook) >> 2) before system-wide suspend (via ->suspend() hook) >> >> For TI SCI devices that are runtime PM enabled, check (1) will be the >> primary method, and will happen when the TI SCI PM domain is powered >> off (e.g. when the runtime PM usecount of the last device in that >> domain goes to zero.) >> >> For devices that are either not runtime PM enabled, or are not yet >> runtime suspended (e.g. due to being used during the suspend path), >> the constraints check will happen by check(2). >> >> Since constraints can be sent by either (1) or (2), driver keeps track >> of whether a valid constraint has been sent already. >> >> 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 >> Signed-off-by: Vibhore Vardhan >> Signed-off-by: Kevin Hilman >> Signed-off-by: Dhruva Gole > > Reviewed-by: Markus Schneider-Pargmann > > In general this looks good, two small things below. > >> --- >> drivers/pmdomain/ti/ti_sci_pm_domains.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 91 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/pmdomain/ti/ti_sci_pm_domains.c b/drivers/pmdomain/ti/ti_sci_pm_domains.c >> index 1510d5ddae3d..4dc48a97f9b8 100644 >> --- a/drivers/pmdomain/ti/ti_sci_pm_domains.c >> +++ b/drivers/pmdomain/ti/ti_sci_pm_domains.c >> @@ -13,6 +13,8 @@ >> #include >> #include >> #include >> +#include >> +#include >> #include >> #include >> >> @@ -47,10 +49,46 @@ struct ti_sci_pm_domain { >> struct generic_pm_domain pd; >> struct list_head node; >> struct ti_sci_genpd_provider *parent; >> + s32 lat_constraint; >> + bool constraint_sent; >> }; >> >> #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; >> +} >> + >> +static int ti_sci_pd_send_constraint(struct device *dev, s32 val) >> +{ >> + 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) { >> + pd->constraint_sent = true; >> + dev_dbg(dev, "ti_sci_pd: ID:%d set latency constraint %d\n", >> + pd->idx, val); >> + } else { >> + dev_err(dev, "ti_sci_pd: set latency constraint failed: ret=%d\n", >> + ret); >> + } >> + >> + return ret; >> +} >> + >> +static inline void ti_sci_pd_clear_constraints(struct device *dev) >> +{ >> + struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain); >> + struct ti_sci_pm_domain *pd = genpd_to_ti_sci_pd(genpd); >> + >> + pd->lat_constraint = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT; >> + pd->constraint_sent = false; >> +} >> + >> /* >> * ti_sci_pd_power_off(): genpd power down hook >> * @domain: pointer to the powerdomain to power off >> @@ -59,6 +97,18 @@ static int ti_sci_pd_power_off(struct generic_pm_domain *domain) >> { >> struct ti_sci_pm_domain *pd = genpd_to_ti_sci_pd(domain); >> const struct ti_sci_handle *ti_sci = pd->parent->ti_sci; >> + struct pm_domain_data *pdd; >> + >> + list_for_each_entry(pdd, &domain->dev_list, list_node) { >> + struct device *dev = pdd->dev; >> + s32 val; >> + >> + /* If device has any resume latency constraints, send 'em */ >> + val = dev_pm_qos_read_value(dev, DEV_PM_QOS_RESUME_LATENCY); >> + if (ti_sci_pd_is_valid_constraint(val) && !pd->constraint_sent) >> + ti_sci_pd_send_constraint(dev, val); >> + pd->lat_constraint = val; >> + } >> >> return ti_sci->ops.dev_ops.put_device(ti_sci, pd->idx); >> } >> @@ -79,6 +129,38 @@ 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_resume(struct device *dev) >> +{ >> + ti_sci_pd_clear_constraints(dev); >> + return pm_generic_resume(dev); >> +} >> + >> +static int ti_sci_pd_suspend(struct device *dev) >> +{ >> + struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain); >> + struct ti_sci_pm_domain *pd = genpd_to_ti_sci_pd(genpd); >> + s32 val; >> + int ret; >> + >> + ret = pm_generic_suspend(dev); >> + if (ret) >> + return ret; >> + >> + /* Check if device has any resume latency constraints */ >> + val = dev_pm_qos_read_value(dev, DEV_PM_QOS_RESUME_LATENCY); >> + if (ti_sci_pd_is_valid_constraint(val) && !pd->constraint_sent) { >> + if (genpd && genpd->status == GENPD_STATE_OFF) >> + dev_warn(dev, "%s: %s: already off.\n", genpd->name, __func__); >> + else if (pm_runtime_suspended(dev)) >> + dev_warn(dev, "%s: %s: already RPM suspended.\n", genpd->name, __func__); >> + else >> + ti_sci_pd_send_constraint(dev, val); >> + } >> + pd->lat_constraint = val; > > Could you get rid of pd->constraint_sent? I don't really see a situation > where it would be necessary. It is necessary for runtime PM enabled devices that also use constraints. For a device like that, if a constraint is present it will be sent when the PM domain is powered off (right after the runtime PM usecount goes to zero.) Later, during system-wide suspend, the suspend hook for that same device might try to send the constraint again if we don't keep track of whether the constraint was already sent. >> + >> + return 0; >> +} >> + >> /* >> * ti_sci_pd_xlate(): translation service for TI SCI genpds >> * @genpdspec: DT identification data for the genpd >> @@ -188,7 +270,15 @@ 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; >> - >> + pd->lat_constraint = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT; > > Optionally you could use ti_sci_pd_clear_constraints() here instead. hmm, yes. Good catch. Kevin