Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754784AbcC3PJM (ORCPT ); Wed, 30 Mar 2016 11:09:12 -0400 Received: from hqemgate15.nvidia.com ([216.228.121.64]:9087 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754749AbcC3PJJ convert rfc822-to-8bit (ORCPT ); Wed, 30 Mar 2016 11:09:09 -0400 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Wed, 30 Mar 2016 08:07:22 -0700 Subject: Re: [PATCH] sbs-battery: fix power status when battery is dry To: YH Huang References: <1458726794-48298-1-git-send-email-yh.huang@mediatek.com> <1458801832.16645.7.camel@mtksdaap41> <1459132330.16645.14.camel@mtksdaap41> <56F95451.5040607@nvidia.com> <1459216353.16645.20.camel@mtksdaap41> <56FA99D0.1010004@nvidia.com> <1459328310.29450.24.camel@mtksdaap41> CC: Daniel Kurtz , , Dmitry Eremin-Solenikov , Sebastian Reichel , "linux-kernel@vger.kernel.org" , "moderated list:ARM/Mediatek SoC support" , Matthias Brugger , David Woodhouse , "linux-arm-kernel@lists.infradead.org" From: Rhyland Klein Message-ID: <56FBEC12.10705@nvidia.com> Date: Wed, 30 Mar 2016 11:09:06 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: <1459328310.29450.24.camel@mtksdaap41> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6722 Lines: 151 On 3/30/2016 4:58 AM, YH Huang wrote: > On Tue, 2016-03-29 at 11:05 -0400, Rhyland Klein wrote: >> On 3/28/2016 9:52 PM, YH Huang wrote: >>> On Mon, 2016-03-28 at 11:57 -0400, Rhyland Klein wrote: >>>> On 3/28/2016 6:05 AM, Daniel Kurtz wrote: >>>>> +Rhyland Klein who original wrote this code... >>>>> >>>>> On Mon, Mar 28, 2016 at 10:32 AM, YH Huang wrote: >>>>>> >>>>>> On Fri, 2016-03-25 at 11:06 +0800, Daniel Kurtz wrote: >>>>>>> On Thu, Mar 24, 2016 at 2:43 PM, YH Huang wrote: >>>>>>>> >>>>>>>> Hi Daniel, >>>>>>>> >>>>>>>> On Thu, 2016-03-24 at 12:01 +0800, Daniel Kurtz wrote: >>>>>>>>> Hi YH, >>>>>>>>> >>>>>>>>> On Wed, Mar 23, 2016 at 5:53 PM, YH Huang wrote: >>>>>>>>>> When the battery is dry and BATTERY_FULL_DISCHARGED is set, >>>>>>>>>> we should check BATTERY_DISCHARGING to decide the power status. >>>>>>>>>> If BATTERY_DISCHARGING is set, the power status is not charging. >>>>>>>>>> Or the power status should be charging. >>>>>>>>>> >>>>>>>>>> Signed-off-by: YH Huang >>>>>>>>>> --- >>>>>>>>>> drivers/power/sbs-battery.c | 22 ++++++++++++---------- >>>>>>>>>> 1 file changed, 12 insertions(+), 10 deletions(-) >>>>>>>>>> >>>>>>>>>> diff --git a/drivers/power/sbs-battery.c b/drivers/power/sbs-battery.c >>>>>>>>>> index d6226d6..d86db0e 100644 >>>>>>>>>> --- a/drivers/power/sbs-battery.c >>>>>>>>>> +++ b/drivers/power/sbs-battery.c >>>>>>>>>> @@ -382,11 +382,12 @@ static int sbs_get_battery_property(struct i2c_client *client, >>>>>>>>>> >>>>>>>>>> if (ret & BATTERY_FULL_CHARGED) >>>>>>>>>> val->intval = POWER_SUPPLY_STATUS_FULL; >>>>>>>>>> - else if (ret & BATTERY_FULL_DISCHARGED) >>>>>>>>>> - val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING; >>>>>>>>>> - else if (ret & BATTERY_DISCHARGING) >>>>>>>>>> - val->intval = POWER_SUPPLY_STATUS_DISCHARGING; >>>>>>>>>> - else >>>>>>>>>> + else if (ret & BATTERY_DISCHARGING) { >>>>>>>>>> + if (ret & BATTERY_FULL_DISCHARGED) >>>>>>>>>> + val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING; >>>>>>>>>> + else >>>>>>>>>> + val->intval = POWER_SUPPLY_STATUS_DISCHARGING; >>>>>>>>>> + } else >>>>>>>>> >>>>>>>>> >>>>>>>>> I think (BATTERY_DISCHARGING && BATTERY_FULL_DISCHARGED) is still >>>>>>>>> POWER_SUPPLY_STATUS_DISCHARGING. >>>>>>>>> So, let's just report what the battery says and do: >>>>>>>>> >>>>>>>>> else if (ret & BATTERY_DISCHARGING) >>>>>>>>> val->intval = POWER_SUPPLY_STATUS_DISCHARGING; >>>>>>>>> >>>>>>>> So we just ignore the special situation (BATTERY_DISCHARGING && >>>>>>>> BATTERY_FULL_DISCHARGED). >>>>>>>> Isn't POWER_SUPPLY_STATUS_NOT_CHARGING a useful information? >>>>>>> >>>>>>> The battery is discharging. The fact that it is also reporting that >>>>>>> it is already "discharged" just seems premature. I would expect to >>>>>>> only see NOT_CHARGING if completely discharged *and* not discharging. >>>>>> >>>>>> I check the "Smart Battery Data Specification Revision 1.1". >>>>>> And there are some words about FULLY_DISCHARGED. >>>>>> "Discharge should be stopped soon." >>>>>> "This status bit may be set prior to the >>>>>> ‘TERMINATE_DISCHARGE_ALARM’ as an early or first level warning of end of >>>>>> battery charge." >>>>>> It looks like the FULLY_DISCHARGED status is used to announce the >>>>>> warning of battery charge and it is still discharging if there is no one >>>>>> takes care of it. >>>> >>>> >>>> The only difference I see in the patch above is that in the case where >>>> DISCHARGING isn't set, it won't check FULL_DISCHARGE. Nothing seems to >>>> be changed in the case where FULL_DISCHARGE & DISCHARGING are set. >>> >>> If battery is dry(FULLY_DISCHARGED) and is charging(No >>> BATTERY_DISCHARGING) by AC at the same time, >>> I think it is better to mark as POWER_SUPPLY_STATUS_CHARGING. >>> Is this right? >>> >> >> Hmm. I can see where you patch would address that situation. From the >> spec, it looks like its expected that the flags should look something >> like this: >> >> capacity (in the course of running from fully_charged to dry to >> recharging...) >> >> full: FULLY_CHARGED >> >> high->low: DISCHARGING >> ~0%: (DISCHARGING & FULLY_DISCHARGED) >> >> ->~20%: FULLY_DISCHARGED >>> ~20%: = charging >> >> From this understanding, it seems like we can't expect FULLY_DISCHARGED >> to ever be the only flag, nor can we expect it to go away when the >> system is initially plugged in. In light of this, I can see why your >> patch is preferable to the existing code, as the existing code could >> imply that the system is either still near 0% when it is in fact >> charging. Of course, ideally the status returned would be "LOW BUT >> CHARGING" but I can see how CHARGING seems like a better option. >> >> I think this patch would be fine if we wanted to cover that case, though >> if we do merge this, we should probably flush out the patch description >> better to clarify why we have to treat FULLY_DISCHARGED as only >> applicable while DISCHARGING. This, IMHO, isn't because the >> FULLY_DISCHARGED flag comes on early, but rather because it doesn't turn >> off until ~20%. > > If I revise the description in this way(using your clear explanation): > ------------------------------------------------------------------------ > The battery capacity changing course is like this: > > full: BATTERY_FULLY_CHARGED => POWER_SUPPLY_STATUS_FULL > > high->low: BATTERY_DISCHARGING => POWER_SUPPLY_STATUS_DISCHARGING > ~0%: DISCHARGING & FULLY_DISCHARGED => POWER_SUPPLY_STATUS_NOT_CHARGING > > 0%~20%: FULLY_DISCHARGED => POWER_SUPPLY_STATUS_CHARGING > 20%~: No flag => POWER_SUPPLY_STATUS_CHARGING > > For now, it is not exactly right to show the status as > POWER_SUPPLY_STATUS_NOT_CHARGING when the battery is dry > (FULLY_DISCHARGED) and AC is plugged in. > Although the battery is in a low level, system works fine with the AC > charging. > It is better to say that the battery is charging. > ------------------------------------------------------------------------ Sounds good. > > How about this? > By the way, should I also revise the title? > well, since the case this is specifically addressing is more to do with charging when very low than being dry, it would probably make sense to change it to "sbs-battery: fix power status when battery charging near dry" or something like that. -rhyland -- nvpublic