From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44EBFC352AA for ; Tue, 1 Oct 2019 10:32:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 27D6521906 for ; Tue, 1 Oct 2019 10:32:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730843AbfJAKcO (ORCPT ); Tue, 1 Oct 2019 06:32:14 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:38768 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725765AbfJAKcO (ORCPT ); Tue, 1 Oct 2019 06:32:14 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id 03D8C28E304 Subject: Re: [PATCH 04/13] platform: chrome: cros-ec: record event timestamp in the hard irq To: Gwendal Grignou , jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, lee.jones@linaro.org, bleung@chromium.org, dianders@chromium.org, groeck@chromium.org, fabien.lahoudere@collabora.com Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org References: <20190922175021.53449-1-gwendal@chromium.org> <20190922175021.53449-5-gwendal@chromium.org> From: Enric Balletbo i Serra Message-ID: <0956b6a6-44ea-8e91-b047-68a021b45c39@collabora.com> Date: Tue, 1 Oct 2019 12:32:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20190922175021.53449-5-gwendal@chromium.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Gwendal, Some comments below. On 22/9/19 19:50, Gwendal Grignou wrote: > To improve sensor timestamp precision, given EC and AP are in > different time domains, the AP needs to try to record the exact > moment an event was signalled to the AP by the EC as soon as > possible after it happens. > > First thing in the hard irq is the best place for this. > > Signed-off-by: Gwendal Grignou > --- > drivers/platform/chrome/cros_ec.c | 18 +++++++++++++++++- > drivers/platform/chrome/cros_ec_lpc.c | 2 ++ > include/linux/platform_data/cros_ec_proto.h | 15 +++++++++++++++ > 3 files changed, 34 insertions(+), 1 deletion(-) > > diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c > index fd77e6fa74c2..f49eb1d1e3cd 100644 > --- a/drivers/platform/chrome/cros_ec.c > +++ b/drivers/platform/chrome/cros_ec.c > @@ -31,6 +31,21 @@ static struct cros_ec_platform pd_p = { > .cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_PD_INDEX), > }; > > +s64 cros_ec_get_time_ns(void) > +{ > + return ktime_get_boottime_ns(); > +} > +EXPORT_SYMBOL(cros_ec_get_time_ns); > + That's a simple wrapper only to make sure all cros_ec drivers use the same code path, right? So maybe instead of doing this we can just add an inline function in the header like this /** * cros_ec_get_time_ns - Get time since boot including time spend in suspend * * Return: ktime_t format since boot. */ static inline ktime_t cros_ec_get_time_ns(void) { return ktime_get_boottime_ns(); } I'd use ktime_t instead of s64 also. Thanks, Enric > +static irqreturn_t ec_irq_handler(int irq, void *data) > +{ > + struct cros_ec_device *ec_dev = data; > + > + ec_dev->last_event_time = cros_ec_get_time_ns(); > + > + return IRQ_WAKE_THREAD; > +} > + > static irqreturn_t ec_irq_thread(int irq, void *data) > { > struct cros_ec_device *ec_dev = data; > @@ -132,7 +147,8 @@ int cros_ec_register(struct cros_ec_device *ec_dev) > } > > if (ec_dev->irq) { > - err = devm_request_threaded_irq(dev, ec_dev->irq, NULL, > + err = devm_request_threaded_irq( > + dev, ec_dev->irq, ec_irq_handler, > ec_irq_thread, IRQF_TRIGGER_LOW | IRQF_ONESHOT, > "chromeos-ec", ec_dev); > if (err) { > diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c > index 7d10d909435f..3c77496e164d 100644 > --- a/drivers/platform/chrome/cros_ec_lpc.c > +++ b/drivers/platform/chrome/cros_ec_lpc.c > @@ -313,6 +313,8 @@ static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data) > { > struct cros_ec_device *ec_dev = data; > > + ec_dev->last_event_time = cros_ec_get_time_ns(); > + > if (ec_dev->mkbp_event_supported && > cros_ec_get_next_event(ec_dev, NULL) > 0) > blocking_notifier_call_chain(&ec_dev->event_notifier, 0, > diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h > index e91e3fcb0348..ab12e28f2107 100644 > --- a/include/linux/platform_data/cros_ec_proto.h > +++ b/include/linux/platform_data/cros_ec_proto.h > @@ -121,6 +121,8 @@ struct cros_ec_command { > * @event_data: Raw payload transferred with the MKBP event. > * @event_size: Size in bytes of the event data. > * @host_event_wake_mask: Mask of host events that cause wake from suspend. > + * @last_event_time: exact time from the hard irq when we got notified of > + * a new event. > * @ec: The platform_device used by the mfd driver to interface with the > * main EC. > * @pd: The platform_device used by the mfd driver to interface with the > @@ -161,6 +163,7 @@ struct cros_ec_device { > int event_size; > u32 host_event_wake_mask; > u32 last_resume_result; > + s64 last_event_time; > > /* The platform devices used by the mfd driver */ > struct platform_device *ec; > @@ -308,4 +311,16 @@ int cros_ec_get_next_event(struct cros_ec_device *ec_dev, bool *wake_event); > */ > u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev); > > +/** > + * cros_ec_get_time_ns - Return time in ns. > + * > + * This is the function used to record the time for last_event_time in struct > + * cros_ec_device during the hard irq. > + * > + * This function is probably implemented using ktime_get_boot_ns(), but it's > + * exposed here to make sure all cros_ec drivers use the same code path to get > + * the time. > + */ > +s64 cros_ec_get_time_ns(void); > + > #endif /* __LINUX_CROS_EC_PROTO_H */ >