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=-11.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 AB244C43331 for ; Sun, 29 Mar 2020 00:34:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67A0F206CC for ; Sun, 29 Mar 2020 00:34:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="YZWIpXz7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727755AbgC2AeB (ORCPT ); Sat, 28 Mar 2020 20:34:01 -0400 Received: from mail-io1-f65.google.com ([209.85.166.65]:36255 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727466AbgC2AeB (ORCPT ); Sat, 28 Mar 2020 20:34:01 -0400 Received: by mail-io1-f65.google.com with SMTP id d15so13883641iog.3 for ; Sat, 28 Mar 2020 17:34:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=PZOXxamCEJ4pJQooOY8Vo9spEOaO/1ETCDCanMSNcIk=; b=YZWIpXz7N7ebsVBY4gyw5EFXHKkiS+YuFdw2uOvHgijvEPadY8XY+aWz8gap8wk7Rp 7rzRxoip3d5JH6174iB0QAB6qeheTN1A2boFICYooUJjV/i54iTeGsXZ/WtY7jW/TndZ c3lnf6UaJX0DJaqaLLDOx9vwp6EFCTOxHJ2rM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PZOXxamCEJ4pJQooOY8Vo9spEOaO/1ETCDCanMSNcIk=; b=QdTUag6Xab+jRQrb1AUDfl3LnVLla1fass0LqyAxNW95m2ngPvqCeFgPQeCswAjJg4 qvxVgxBTNPttkW+LQgR2uRS0cDruQ2Ij9ntZNlTsDZHfXhc0ODw13AWNyBL9lBsXkmrY m/mWYCNDaAdYKXbMTQKCDHTLga9q+TycvC46PIjn9vpvjbDp3wi5Io4O76y6cvrhklAO 6vxKbUY32Wsvgzf2pe4wfiLbPG4ajqOTnYqw+mINYr6v7RVEI+eOOAlEWe4FgiXvz1a1 MRF5o0mxb0SUejjCyKNuFbgCSh2aZuVZyR5BDip6jsX82ENh0CEKGumDYPn7allBI7DY 2ndw== X-Gm-Message-State: ANhLgQ1sOr/Bc4IccgMbb5oJA5QG6/dXUkvyzdI5O91EwmmYQCLpZJdo qHRU0iM6C0FbrkSyYfRUQTG0bHIGcJcn4Ynj1FAfag== X-Google-Smtp-Source: ADFU+vtZgYpobw5MVLLk+5ci/NZSPJCUPVLm2Mda0qDub/Gv1hERtB9YqQQsjao4KhMhGyeptUfOXId1MzgtQD7vZeE= X-Received: by 2002:a05:6638:733:: with SMTP id j19mr5300490jad.131.1585442039546; Sat, 28 Mar 2020 17:33:59 -0700 (PDT) MIME-Version: 1.0 References: <20200327223443.6006-1-gwendal@chromium.org> <20200327223443.6006-13-gwendal@chromium.org> <20200328172256.583b483e@archlinux> In-Reply-To: <20200328172256.583b483e@archlinux> From: Gwendal Grignou Date: Sat, 28 Mar 2020 17:33:48 -0700 Message-ID: Subject: Re: [PATCH v7 12/12] iio: cros_ec: flush as hwfifo attribute To: Jonathan Cameron Cc: Benson Leung , Enric Balletbo i Serra , Jonathan Cameron , linux-iio , linux-kernel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 28, 2020 at 10:22 AM Jonathan Cameron wrote: > > On Fri, 27 Mar 2020 15:34:43 -0700 > Gwendal Grignou wrote: > > > Add buffer/hwfifo_flush. It is not part of the ABI, but it follows ST > > and HID lead: Tells the sensor hub to send to the host all pending > > sensor events. > > > > Signed-off-by: Gwendal Grignou > > Unless I'm missing something there aren't any other drivers providing > an explicit flush attribute. The flush attribute comes from a requirement from Android to ask the sensorhub to flush the samples still in its FIFO queue. (see https://source.android.com/devices/sensors/hal-interface#flush_sensor) It has been implemented in the ST Android HAL, which expects a hw_fifo_flush attribute.: https://github.com/STMicroelectronics/STMems_Android_Sensor_HAL_IIO/blob/STMems_Android_Sensor_HAL_IIO/src/utils.cpp#L31 But I misread kernel ST code; as you said, the request to flush appends only when the buffer is enabled/disabled or the sensor suspended, it is not exposed to user space. For Bosh sensor : there is a patch that was proposed a while back: "http://lkml.iu.edu/hypermail/linux/kernel/1504.3/03270.html", but it never reached mainline. For HID, the attribute is defined in the HID specification (31C) : https://www.usb.org/sites/default/files/hutrr59_-_usages_for_wearables_0.pdf but I could not find a publicly available proposed change request that uses it. Anyhow, it was a mistake to put this patch in the current patch set. I need it on chromebook for supporting Android, but it should be discussed more widely to have it part of the ABI, or define a better solution. > The nearest equivalent is the flush > callback which reads out stuff that is in a fifo to be read, but which > hasn't yet reached a watermark to trigger normal readback. > > Can we do something similar here? > > If not this needs ABI documentation in Documentation/ABI/testing/... > I'm not keen on it in becoming general ABI unless I'm missing a > strong argument in favour of it. > > Jonathan Thank you for your support, Gwendal. > > > > --- > > No changes in v7. > > New in v6. > > > > .../cros_ec_sensors/cros_ec_sensors_core.c | 28 +++++++++++++++++++ > > 1 file changed, 28 insertions(+) > > > > diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c > > index c831915ca7e56..aaf124a82e0e4 100644 > > --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c > > +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c > > @@ -113,6 +113,33 @@ static int cros_ec_sensor_set_ec_rate(struct cros_ec_sensors_core_state *st, > > return ret; > > } > > > > +static ssize_t cros_ec_sensors_flush(struct device *dev, > > + struct device_attribute *attr, > > + const char *buf, size_t len) > > +{ > > + struct iio_dev *indio_dev = dev_to_iio_dev(dev); > > + struct cros_ec_sensors_core_state *st = iio_priv(indio_dev); > > + int ret = 0; > > + bool flush; > > + > > + ret = strtobool(buf, &flush); > > + if (ret < 0) > > + return ret; > > + if (!flush) > > + return -EINVAL; > > + > > + mutex_lock(&st->cmd_lock); > > + st->param.cmd = MOTIONSENSE_CMD_FIFO_FLUSH; > > + ret = cros_ec_motion_send_host_cmd(st, 0); > > + if (ret != 0) > > + dev_warn(&indio_dev->dev, "Unable to flush sensor\n"); > > + mutex_unlock(&st->cmd_lock); > > + return ret ? ret : len; > > +} > > + > > +static IIO_DEVICE_ATTR(hwfifo_flush, 0644, NULL, > > + cros_ec_sensors_flush, 0); > > + > > static ssize_t cros_ec_sensor_set_report_latency(struct device *dev, > > struct device_attribute *attr, > > const char *buf, size_t len) > > @@ -175,6 +202,7 @@ static ssize_t hwfifo_watermark_max_show(struct device *dev, > > static IIO_DEVICE_ATTR_RO(hwfifo_watermark_max, 0); > > > > const struct attribute *cros_ec_sensor_fifo_attributes[] = { > > + &iio_dev_attr_hwfifo_flush.dev_attr.attr, > > &iio_dev_attr_hwfifo_timeout.dev_attr.attr, > > &iio_dev_attr_hwfifo_watermark_max.dev_attr.attr, > > NULL, >