Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754905AbaA1OTg (ORCPT ); Tue, 28 Jan 2014 09:19:36 -0500 Received: from mail-lb0-f179.google.com ([209.85.217.179]:59653 "EHLO mail-lb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754513AbaA1OTf (ORCPT ); Tue, 28 Jan 2014 09:19:35 -0500 MIME-Version: 1.0 In-Reply-To: <20140128091258.GY18029@intel.com> References: <1389694438-18614-1-git-send-email-mika.westerberg@linux.intel.com> <20140128091258.GY18029@intel.com> Date: Tue, 28 Jan 2014 09:19:33 -0500 Message-ID: Subject: Re: [PATCH] HID: i2c-hid: add runtime PM support From: Benjamin Tissoires To: Mika Westerberg Cc: linux-input , Jiri Kosina , Benjamin Tissoires , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > >> > 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 :) > >> 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... Cheers, Benjamin -- 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/