From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Brian Norris <briannorris@chromium.org>
Cc: Thierry Reding <thierry.reding@gmail.com>,
linux-pwm@vger.kernel.org, Mark Brown <broonie@kernel.org>,
Liam Girdwood <lgirdwood@gmail.com>,
Heiko Stuebner <heiko@sntech.de>,
linux-rockchip@lists.infradead.org,
Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Milo Kim <milo.kim@ti.com>,
Doug Anderson <dianders@google.com>,
Caesar Wang <wxt@rock-chips.com>,
Stephen Barber <smbarber@chromium.org>,
Srinivas Kandagatla <srinivas.kandagatla@gmail.com>,
Maxime Coquelin <maxime.coquelin@st.com>,
Patrice Chotard <patrice.chotard@st.com>,
kernel@stlinux.com, Laxman Dewangan <ldewangan@nvidia.com>
Subject: Re: [PATCH 10/14] regulator: pwm: Switch to the atomic PWM API
Date: Sat, 4 Jun 2016 08:28:48 +0200 [thread overview]
Message-ID: <20160604082848.0b897b14@bbrezillon> (raw)
In-Reply-To: <20160603205028.GH124478@google.com>
On Fri, 3 Jun 2016 13:50:28 -0700
Brian Norris <briannorris@chromium.org> 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 <boris.brezillon@free-electrons.com>
> > ---
> > 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 <briannorris@chromium.org>
> Tested-by: Brian Norris <briannorris@chromium.org>
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
next prev parent reply other threads:[~2016-06-04 6:28 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-03 8:22 [PATCH 00/14] regulator: pwm: various improvements Boris Brezillon
2016-06-03 8:22 ` [PATCH 01/14] pwm: Add new helpers to create/manipulate PWM states Boris Brezillon
2016-06-03 8:23 ` [PATCH 04/14] pwm: rockchip: Add support for hardware readout Boris Brezillon
2016-06-03 20:07 ` Brian Norris
2016-06-03 20:20 ` Brian Norris
2016-06-04 6:24 ` Boris Brezillon
2016-06-07 17:26 ` Brian Norris
[not found] ` <1464942192-25967-1-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2016-06-03 8:23 ` [PATCH 02/14] regulator: pwm: Drop unneeded pwm_enable() call Boris Brezillon
2016-06-03 11:08 ` Applied "regulator: pwm: Drop unneeded pwm_enable() call" to the regulator tree Mark Brown
2016-06-03 8:23 ` [PATCH 03/14] pwm: rockchip: Fix period and duty_cycle approximation Boris Brezillon
2016-06-03 20:03 ` Brian Norris
2016-06-04 6:19 ` Boris Brezillon
2016-06-07 17:25 ` Brian Norris
2016-06-03 8:23 ` [PATCH 05/14] pwm: rockchip: Avoid glitches on already running PWMs Boris Brezillon
2016-06-03 20:28 ` Brian Norris
2016-06-04 6:26 ` Boris Brezillon
2016-06-03 8:23 ` [PATCH 07/14] pwm: sti: Add support for hardware readout Boris Brezillon
2016-06-03 8:23 ` [PATCH 11/14] regulator: pwm: properly initialize the ->state field Boris Brezillon
2016-06-03 20:51 ` Brian Norris
2016-06-03 8:23 ` [PATCH 12/14] regulator: pwm: Retrieve correct voltage Boris Brezillon
2016-06-03 20:55 ` Brian Norris
2016-06-03 8:23 ` [PATCH 06/14] pwm: rockchip: Add support for atomic update Boris Brezillon
[not found] ` <1464942192-25967-7-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2016-06-03 20:37 ` Brian Norris
2016-06-03 8:23 ` [PATCH 08/14] pwm: sti: Avoid glitches on already running PWMs Boris Brezillon
2016-06-03 20:38 ` Brian Norris
2016-06-03 8:23 ` [PATCH 09/14] regulator: pwm: Adjust PWM config at probe time Boris Brezillon
2016-06-03 20:41 ` Brian Norris
2016-06-03 8:23 ` [PATCH 10/14] regulator: pwm: Switch to the atomic PWM API Boris Brezillon
[not found] ` <1464942192-25967-11-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2016-06-03 20:50 ` Brian Norris
2016-06-04 6:28 ` Boris Brezillon [this message]
2016-06-06 6:14 ` Laxman Dewangan
2016-06-03 8:23 ` [PATCH 13/14] regulator: pwm: Support extra continuous mode cases Boris Brezillon
2016-06-03 21:03 ` Brian Norris
2016-06-04 6:30 ` Boris Brezillon
2016-06-03 8:23 ` [PATCH 14/14] regulator: pwm: Document pwm-dutycycle-unit and pwm-dutycycle-range Boris Brezillon
[not found] ` <1464942192-25967-15-git-send-email-boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2016-06-03 21:04 ` Brian Norris
2016-06-06 14:09 ` Rob Herring
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160604082848.0b897b14@bbrezillon \
--to=boris.brezillon@free-electrons.com \
--cc=briannorris@chromium.org \
--cc=broonie@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=dianders@google.com \
--cc=galak@codeaurora.org \
--cc=heiko@sntech.de \
--cc=ijc+devicetree@hellion.org.uk \
--cc=kernel@stlinux.com \
--cc=ldewangan@nvidia.com \
--cc=lgirdwood@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-rockchip@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=maxime.coquelin@st.com \
--cc=milo.kim@ti.com \
--cc=patrice.chotard@st.com \
--cc=pawel.moll@arm.com \
--cc=robh+dt@kernel.org \
--cc=smbarber@chromium.org \
--cc=srinivas.kandagatla@gmail.com \
--cc=thierry.reding@gmail.com \
--cc=wxt@rock-chips.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).