Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751116AbaA2JGT (ORCPT ); Wed, 29 Jan 2014 04:06:19 -0500 Received: from mga09.intel.com ([134.134.136.24]:25907 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750930AbaA2JGK (ORCPT ); Wed, 29 Jan 2014 04:06:10 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.95,741,1384329600"; d="scan'208";a="466490270" Date: Wed, 29 Jan 2014 11:13:13 +0200 From: Mika Westerberg To: Benjamin Tissoires Cc: linux-input , Jiri Kosina , Benjamin Tissoires , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] HID: i2c-hid: add runtime PM support Message-ID: <20140129091313.GK18029@intel.com> References: <1389694438-18614-1-git-send-email-mika.westerberg@linux.intel.com> <20140128091258.GY18029@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 28, 2014 at 09:19:33AM -0500, Benjamin Tissoires wrote: > On Tue, Jan 28, 2014 at 4:12 AM, Mika Westerberg > wrote: > > On Mon, Jan 27, 2014 at 10:36:25PM -0500, Benjamin Tissoires wrote: > >> On Tue, Jan 14, 2014 at 5:13 AM, Mika Westerberg > >> wrote: > >> > This patch adds runtime PM support for the HID over I2C driver. When the > >> > i2c-hid device is first opened we power it on and on the last close we > >> > power it off. > >> > > >> > The implementation is not the most power efficient because it needs some > >> > interaction from the userspace (e.g close the device node whenever we are > >> > no more interested in getting events), nevertheless it allows us to save > >> > some power and works with devices that are not wake capable. > >> > > >> > >> Hi Mika, > >> > >> I am a little bit puzzled here. The commit message just says that you > >> changed the implementation of the power saving with the exact same > >> behavior... At least that's what I understand. > >> Currently, the devices should be put on sleep if nobody is reading, > >> and back alive if a reader arrives. > >> I think there is a gain with the patch, but my knowledge of the pm > >> subsystem is far too limited to see it :( > > > > Yes, there should be gain. If there is power domain involved like, ACPI in > > our case, runtime suspending the device on close will let ACPI to move the > > device to D3cold (e.g full off) which saves more power. > > Oh, right. So, if you could just put this last sentence in the commit > message, that would be great. Sure. > > > > >> > Signed-off-by: Mika Westerberg > >> > --- > >> > drivers/hid/i2c-hid/i2c-hid.c | 81 ++++++++++++++++++++++++++++--------------- > >> > 1 file changed, 54 insertions(+), 27 deletions(-) > >> > > >> > diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c > >> > index d1f81f52481a..ff767d03d60e 100644 > >> > --- a/drivers/hid/i2c-hid/i2c-hid.c > >> > +++ b/drivers/hid/i2c-hid/i2c-hid.c > >> > @@ -25,6 +25,7 @@ > >> > #include > >> > #include > >> > #include > >> > +#include > >> > #include > >> > #include > >> > #include > >> > @@ -454,10 +455,18 @@ static void i2c_hid_init_reports(struct hid_device *hid) > >> > return; > >> > } > >> > > >> > + /* > >> > + * The device must be powered on while we fetch initial reports > >> > + * from it. > >> > + */ > >> > + pm_runtime_get_sync(&client->dev); > >> > + > >> > list_for_each_entry(report, > >> > &hid->report_enum[HID_FEATURE_REPORT].report_list, list) > >> > i2c_hid_init_report(report, inbuf, ihid->bufsize); > >> > > >> > + pm_runtime_put(&client->dev); > >> > + > >> > kfree(inbuf); > >> > } > >> > > >> > @@ -703,8 +712,8 @@ static int i2c_hid_open(struct hid_device *hid) > >> > > >> > mutex_lock(&i2c_hid_open_mut); > >> > if (!hid->open++) { > >> > - ret = i2c_hid_set_power(client, I2C_HID_PWR_ON); > >> > - if (ret) { > >> > + ret = pm_runtime_get_sync(&client->dev); > >> > >> dummy question (kind of late here...). Is there a counter of how many > >> get/put has been called in pm_runtime which could allow us to get rid > >> of the hid->open count? > > > > There is a counter but I'm not sure if drivers are supposed to use that. I > > would prefer not to use that. > > ok > > > > >> > >> > + if (ret < 0) { > >> > hid->open--; > >> > goto done; > >> > } > >> > @@ -712,7 +721,7 @@ static int i2c_hid_open(struct hid_device *hid) > >> > } > >> > done: > >> > mutex_unlock(&i2c_hid_open_mut); > >> > - return ret; > >> > + return ret < 0 ? ret : 0; > >> > } > >> > > >> > static void i2c_hid_close(struct hid_device *hid) > >> > @@ -729,37 +738,17 @@ static void i2c_hid_close(struct hid_device *hid) > >> > clear_bit(I2C_HID_STARTED, &ihid->flags); > >> > > >> > /* Save some power */ > >> > - i2c_hid_set_power(client, I2C_HID_PWR_SLEEP); > >> > + pm_runtime_put(&client->dev); > >> > } > >> > mutex_unlock(&i2c_hid_open_mut); > >> > } > >> > > >> > -static int i2c_hid_power(struct hid_device *hid, int lvl) > >> > -{ > >> > - struct i2c_client *client = hid->driver_data; > >> > - struct i2c_hid *ihid = i2c_get_clientdata(client); > >> > - int ret = 0; > >> > - > >> > - i2c_hid_dbg(ihid, "%s lvl:%d\n", __func__, lvl); > >> > - > >> > - switch (lvl) { > >> > - case PM_HINT_FULLON: > >> > - ret = i2c_hid_set_power(client, I2C_HID_PWR_ON); > >> > - break; > >> > - case PM_HINT_NORMAL: > >> > - ret = i2c_hid_set_power(client, I2C_HID_PWR_SLEEP); > >> > - break; > >> > - } > >> > - return ret; > >> > -} > >> > - > >> > static struct hid_ll_driver i2c_hid_ll_driver = { > >> > .parse = i2c_hid_parse, > >> > .start = i2c_hid_start, > >> > .stop = i2c_hid_stop, > >> > .open = i2c_hid_open, > >> > .close = i2c_hid_close, > >> > - .power = i2c_hid_power, > >> > >> If I understand correctly, here you are trying to fix hidraw (with > >> i2c_hid tramsport) which used to set_power on/off twice with the first > >> reader, right? > > > > Right. > > > >> I don't think we have other i2c_hid users of hid_hw_power, but I am a > >> little bit worried of simply removing the callback. > > > > OK. > > > >> What if we just change i2c_hid_set_power in i2c_hid_power by the > >> corresponding pm_runtime calls? > > > > Sure, I'll change that in the next version. > > > >> > >> > .request = i2c_hid_request, > >> > }; > >> > > >> > @@ -973,13 +962,17 @@ static int i2c_hid_probe(struct i2c_client *client, > >> > if (ret < 0) > >> > goto err; > >> > > >> > + pm_runtime_get_noresume(&client->dev); > >> > + pm_runtime_set_active(&client->dev); > >> > + pm_runtime_enable(&client->dev); > >> > + > >> > ret = i2c_hid_fetch_hid_descriptor(ihid); > >> > if (ret < 0) > >> > - goto err; > >> > + goto err_pm; > >> > > >> > ret = i2c_hid_init_irq(client); > >> > if (ret < 0) > >> > - goto err; > >> > + goto err_pm; > >> > > >> > hid = hid_allocate_device(); > >> > if (IS_ERR(hid)) { > >> > @@ -1010,6 +1003,7 @@ static int i2c_hid_probe(struct i2c_client *client, > >> > goto err_mem_free; > >> > } > >> > > >> > + pm_runtime_put(&client->dev); > >> > return 0; > >> > > >> > err_mem_free: > >> > @@ -1018,6 +1012,10 @@ err_mem_free: > >> > err_irq: > >> > free_irq(client->irq, ihid); > >> > > >> > +err_pm: > >> > + pm_runtime_put_noidle(&client->dev); > >> > + pm_runtime_disable(&client->dev); > >> > + > >> > err: > >> > i2c_hid_free_buffers(ihid); > >> > kfree(ihid); > >> > @@ -1029,6 +1027,11 @@ static int i2c_hid_remove(struct i2c_client *client) > >> > struct i2c_hid *ihid = i2c_get_clientdata(client); > >> > struct hid_device *hid; > >> > > >> > + pm_runtime_get_sync(&client->dev); > >> > + pm_runtime_disable(&client->dev); > >> > + pm_runtime_set_suspended(&client->dev); > >> > + pm_runtime_put_noidle(&client->dev); > >> > + > >> > hid = ihid->hid; > >> > hid_destroy_device(hid); > >> > > >> > @@ -1074,7 +1077,31 @@ static int i2c_hid_resume(struct device *dev) > >> > } > >> > #endif > >> > > >> > -static SIMPLE_DEV_PM_OPS(i2c_hid_pm, i2c_hid_suspend, i2c_hid_resume); > >> > +#ifdef CONFIG_PM_RUNTIME > >> > +static int i2c_hid_runtime_suspend(struct device *dev) > >> > +{ > >> > + struct i2c_client *client = to_i2c_client(dev); > >> > + > >> > + i2c_hid_set_power(client, I2C_HID_PWR_SLEEP); > >> > + disable_irq(client->irq); > >> > + return 0; > >> > +} > >> > + > >> > +static int i2c_hid_runtime_resume(struct device *dev) > >> > +{ > >> > + struct i2c_client *client = to_i2c_client(dev); > >> > + > >> > + enable_irq(client->irq); > >> > + i2c_hid_set_power(client, I2C_HID_PWR_ON); > >> > + return 0; > >> > +} > >> > >> These two functions looks very similar to i2c_hid_suspend and > >> i2c_hid_resume, without the reset and the irq_wake :( > >> So, my question here is can we use some common code for them? > >> It may not be possible regarding CONFIG_PM_RUNTIME and > >> CONFIG_PM_SLEEP, but it still looks ugly to me. > > > > It looks ugly, I agree and we can probably reuse some code in the > > callbacks. I'll look into that. > > well, anyway, if this involve something even more ugly, we can for > sure stick with this version :) It turned out that it is going to be ugly, no matter what :-( I'll keep the current version for now. > > > > >> I tested this today, and it works, so you should be right, but I'd > >> like to have your opinion on this. > > > > Thanks for testing and comments. > > > > I'll prepare a new version with the suggested changes if you are OK with my > > explanations ;-) > > Sure I am. Thanks for handling the whole ACPI part of this module. I > was really pleased the other day to see that the touchscreen of a Bay > trail tablet is now working out of the box :) I still have many other > problems with this tablet, but still, having the input working is > always good with a tablet... If that's the Asus T100 tablet, we are going to fix rest of the problems soon :-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/