From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH 10/14] regulator: pwm: Switch to the atomic PWM API Date: Sat, 4 Jun 2016 08:28:48 +0200 Message-ID: <20160604082848.0b897b14@bbrezillon> References: <1464942192-25967-1-git-send-email-boris.brezillon@free-electrons.com> <1464942192-25967-11-git-send-email-boris.brezillon@free-electrons.com> <20160603205028.GH124478@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160603205028.GH124478@google.com> Sender: linux-pwm-owner@vger.kernel.org To: Brian Norris Cc: Thierry Reding , linux-pwm@vger.kernel.org, Mark Brown , Liam Girdwood , Heiko Stuebner , linux-rockchip@lists.infradead.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Milo Kim , Doug Anderson , Caesar Wang , Stephen Barber , Srinivas Kandagatla , Maxime Coquelin , Patrice Chotard , kernel@stlinux.com, Laxman Dewangan List-Id: devicetree@vger.kernel.org On Fri, 3 Jun 2016 13:50:28 -0700 Brian Norris wrote: > + Laxman > > Hi, > > On Fri, Jun 03, 2016 at 10:23:08AM +0200, Boris Brezillon wrote: > > Use the atomic API wherever appropriate and get rid of pwm_apply_args() > > call (the reference period and polarity are now explicitly set when > > calling pwm_apply_state()). > > > > We also make use of the pwm_set_relative_duty_cycle() helper to ease > > relative to absolute duty_cycle conversion. > > > > Signed-off-by: Boris Brezillon > > --- > > drivers/regulator/pwm-regulator.c | 38 ++++++++++---------------------------- > > 1 file changed, 10 insertions(+), 28 deletions(-) > > > > diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c > > index 524b43f..bf033fd 100644 > > --- a/drivers/regulator/pwm-regulator.c > > +++ b/drivers/regulator/pwm-regulator.c > > @@ -59,16 +59,14 @@ static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev, > > unsigned selector) > > { > > struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev); > > - struct pwm_args pargs; > > - int dutycycle; > > + struct pwm_state pstate; > > int ret; > > > > - pwm_get_args(drvdata->pwm, &pargs); > > + pwm_prepare_new_state(drvdata->pwm, &pstate); > > + pwm_set_relative_duty_cycle(&pstate, > > + drvdata->duty_cycle_table[selector].dutycycle, 100); > > > > - dutycycle = (pargs.period * > > - drvdata->duty_cycle_table[selector].dutycycle) / 100; > > - > > - ret = pwm_config(drvdata->pwm, dutycycle, pargs.period); > > + ret = pwm_apply_state(drvdata->pwm, &pstate); > > if (ret) { > > dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret); > > return ret; > > @@ -126,34 +124,18 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev, > > { > > struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev); > > unsigned int ramp_delay = rdev->constraints->ramp_delay; > > - struct pwm_args pargs; > > unsigned int req_diff = min_uV - rdev->constraints->min_uV; > > + struct pwm_state pstate; > > unsigned int diff; > > - unsigned int duty_pulse; > > - u64 req_period; > > - u32 rem; > > int ret; > > > > - pwm_get_args(drvdata->pwm, &pargs); > > + pwm_prepare_new_state(drvdata->pwm, &pstate); > > diff = rdev->constraints->max_uV - rdev->constraints->min_uV; > > > > - /* First try to find out if we get the iduty cycle time which is > > - * factor of PWM period time. If (request_diff_to_min * pwm_period) > > - * is perfect divided by voltage_range_diff then it is possible to > > - * get duty cycle time which is factor of PWM period. This will help > > - * to get output voltage nearer to requested value as there is no > > - * calculation loss. > > - */ > > - req_period = req_diff * pargs.period; > > - div_u64_rem(req_period, diff, &rem); > > - if (!rem) { > > - do_div(req_period, diff); > > - duty_pulse = (unsigned int)req_period; > > - } else { > > - duty_pulse = (pargs.period / 100) * ((req_diff * 100) / diff); > > - } > > + /* We pass diff as the scale to get a uV precision. */ > > + pwm_set_relative_duty_cycle(&pstate, req_diff, diff); > > Notably, you're dropping much of Laxman's commit fd786fb0276a ("regulator: > pwm: Try to avoid voltage error in duty cycle calculation"), but I > believe the DIV_ROUND_CLOSEST_ULL() in pwm_set_relative_duty_cycle() > solves his problem better. Oops, forgot to comment on that in the commit message. Indeed, the use of pwm_set_relative_duty_cycle() solves the problem Laxman was seeing. > > > > > - ret = pwm_config(drvdata->pwm, duty_pulse, pargs.period); > > + ret = pwm_apply_state(drvdata->pwm, &pstate); > > if (ret) { > > dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret); > > return ret; > > Reviewed-by: Brian Norris > Tested-by: Brian Norris -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com