From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752193AbaGKCqo (ORCPT ); Thu, 10 Jul 2014 22:46:44 -0400 Received: from mga11.intel.com ([192.55.52.93]:14874 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751364AbaGKCqn convert rfc822-to-8bit (ORCPT ); Thu, 10 Jul 2014 22:46:43 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,641,1400050800"; d="scan'208";a="568254487" From: "Tc, Jenny" To: Sebastian Reichel CC: "linux-kernel@vger.kernel.org" , "Dmitry Eremin-Solenikov" , Pavel Machek , Stephen Rothwell , Anton Vorontsov , David Woodhouse , "David Cohen" , "Pallala, Ramakrishna" Subject: RE: [PATCH 3/4] power_supply: Introduce PSE compliant algorithm Thread-Topic: [PATCH 3/4] power_supply: Introduce PSE compliant algorithm Thread-Index: AQHPlEmiwCL4psBg3UmQFWJgLR5uO5uOGRuAgAejXICAAEkMAIABPgGA Date: Fri, 11 Jul 2014 02:46:35 +0000 Message-ID: <20ADAB092842284E95860F279283C56422F9B99C@BGSMSX104.gar.corp.intel.com> References: <1404122155-12369-1-git-send-email-jenny.tc@intel.com> <1404122155-12369-4-git-send-email-jenny.tc@intel.com> <20140703145617.GA23309@earth.universe> <20ADAB092842284E95860F279283C56422F95A3E@BGSMSX104.gar.corp.intel.com> <20140708155614.GA12945@earth.universe> In-Reply-To: <20140708155614.GA12945@earth.universe> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.223.10.10] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From: Sebastian Reichel [mailto:sre@kernel.org] > Sent: Tuesday, July 08, 2014 9:26 PM > To: Tc, Jenny > Cc: linux-kernel@vger.kernel.org; Dmitry Eremin-Solenikov; Pavel Machek; Stephen > Rothwell; Anton Vorontsov; David Woodhouse; David Cohen; Pallala, Ramakrishna > Subject: Re: [PATCH 3/4] power_supply: Introduce PSE compliant algorithm > > On Tue, Jul 08, 2014 at 06:07:29AM +0000, Tc, Jenny wrote: > > > > +static int get_tempzone(struct psy_pse_chrg_prof *pse_mod_bprof, > > > > + int temp) > > > > +{ > > > > + int i = 0; > > > > + int temp_range_cnt; > > > > + > > > > + temp_range_cnt = min_t(u16, pse_mod_bprof->temp_mon_ranges, > > > > + BATT_TEMP_NR_RNG); > > > > + if ((temp < pse_mod_bprof->temp_low_lim) || > > > > + (temp > pse_mod_bprof->temp_mon_range[0].temp_up_lim)) > > > > + return -EINVAL; > > > > + > > > > + for (i = 0; i < temp_range_cnt; ++i) > > > > + if (temp > pse_mod_bprof->temp_mon_range[i].temp_up_lim) > > > > + break; > > > > + return i-1; > > > > +} > > > > > > pse_mod_bprof->temp_mon_ranges > BATT_TEMP_NR_RNG is not allowed, so > > > I suggest to print an error and return some error code. > > > > > min_t takes care of the upper bound. The algorithm process > > BATT_TEMP_NR_RNG even if the actual number of zones are greater than this. > > Right, the function will not fail, but the zone information table is truncated. I would > expect at least warning about that. I think it doesn't hurt to have a small function, > which validates the zone data as good as possible. Using incorrect temperature > zones is a safety thread and we should try our best to avoid exploding batteries ;) > > Maybe something like that: > > static bool check_tempzones(struct psy_pse_chrg_prof *pse_mod_bprof) { > int i = 0; > int last_temp = ; > > /* check size */ > if (BATT_TEMP_NR_RNG > pse_mod_bprof->temp_mon_ranges) > return false; This is in a way good to have, OK to implement the same. But KO with below suggestion. This doesn't guarantee safety. IMHO Safety is 1/0 - SAFE or NOT SAFE. No half safety. To ensure complete safety, measures should be taken at the entry point- where data is read from external source. Since the algorithm gets the data from internal kernel component (power_supply_charger.c), it trust the data. Since the data is originated from battery identification driver, the safety should be ensured at that level. > > /* check zone order */ > for (i = 0; i < pse_mod_bprof->temp_mon_ranges; i++) { > if (last_temp < pse_mod_bprof->temp_mon_range[i].temp_up_lim) > return false; > last_temp = pse_mod_bprof->temp_mon_range[i].temp_up_lim; > } > > return true; > } > > -- Sebastian