From: Lukasz Majewski <l.majewski@majess.pl>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
Sascha Hauer <s.hauer@pengutronix.de>,
Stefan Agner <stefan@agner.ch>,
linux-pwm@vger.kernel.org,
Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>,
linux-kernel@vger.kernel.org,
Fabio Estevam <fabio.estevam@nxp.com>,
Fabio Estevam <festevam@gmail.com>,
Lothar Wassmann <LW@karo-electronics.de>,
kernel@pengutronix.de
Subject: Re: [PATCH v3 RESEND 07/11] pwm: imx: Provide atomic PWM support for i.MX PWMv2
Date: Thu, 29 Dec 2016 17:45:35 +0100 [thread overview]
Message-ID: <20161229174535.01b87fb7@jawa> (raw)
In-Reply-To: <20161229172117.523a42a4@bbrezillon>
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Hi Boris,
> Hi Lukasz,
>
> On Mon, 26 Dec 2016 23:55:57 +0100
> Lukasz Majewski <l.majewski@majess.pl> wrote:
>
> > This commit provides apply() callback implementation for i.MX's
> > PWMv2.
> >
> > Suggested-by: Stefan Agner <stefan@agner.ch>
> > Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
> > Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > ---
> > Changes for v3:
> > - Remove ipg clock enable/disable functions
> >
> > Changes for v2:
> > - None
> > ---
> > drivers/pwm/pwm-imx.c | 70
> > +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed,
> > 70 insertions(+)
> >
> > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> > index ebe9b0c..cd53c05 100644
> > --- a/drivers/pwm/pwm-imx.c
> > +++ b/drivers/pwm/pwm-imx.c
> > @@ -159,6 +159,75 @@ static void imx_pwm_wait_fifo_slot(struct
> > pwm_chip *chip, }
> > }
> >
> > +static int imx_pwm_apply_v2(struct pwm_chip *chip, struct
> > pwm_device *pwm,
> > + struct pwm_state *state)
> > +{
> > + unsigned long period_cycles, duty_cycles, prescale;
> > + struct imx_chip *imx = to_imx_chip(chip);
> > + struct pwm_state cstate;
> > + unsigned long long c;
> > + u32 cr = 0;
> > + int ret;
> > +
> > + pwm_get_state(pwm, &cstate);
> > +
> > + c = clk_get_rate(imx->clk_per);
> > + c *= state->period;
> > +
> > + do_div(c, 1000000000);
> > + period_cycles = c;
> > +
> > + prescale = period_cycles / 0x10000 + 1;
> > +
> > + period_cycles /= prescale;
> > + c = (unsigned long long)period_cycles * state->duty_cycle;
> > + do_div(c, state->period);
> > + duty_cycles = c;
> > +
> > + /*
> > + * according to imx pwm RM, the real period value should be
> > + * PERIOD value in PWMPR plus 2.
> > + */
> > + if (period_cycles > 2)
> > + period_cycles -= 2;
> > + else
> > + period_cycles = 0;
> > +
> > + /* Enable the clock if the PWM is being enabled. */
> > + if (state->enabled && !cstate.enabled) {
> > + ret = clk_prepare_enable(imx->clk_per);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + /*
> > + * Wait for a free FIFO slot if the PWM is already
> > enabled, and flush
> > + * the FIFO if the PWM was disabled and is about to be
> > enabled.
> > + */
> > + if (cstate.enabled)
> > + imx_pwm_wait_fifo_slot(chip, pwm);
> > + else if (state->enabled)
> > + imx_pwm_sw_reset(chip);
> > +
> > + writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
> > + writel(period_cycles, imx->mmio_base + MX3_PWMPR);
> > +
> > + cr |= MX3_PWMCR_PRESCALER(prescale) |
> > + MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
> > + MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
> > +
> > + if (state->enabled)
> > + cr |= MX3_PWMCR_EN;
> > +
> > + writel(cr, imx->mmio_base + MX3_PWMCR);
> > +
> > + /* Disable the clock if the PWM is being disabled. */
> > + if (!state->enabled && cstate.enabled)
> > + clk_disable_unprepare(imx->clk_per);
> > +
> > + return 0;
> > +}
> > +
>
> Stefan suggested to rework this function to avoid unneeded
> duty/period calculation and reg write when disabling the PWM. Why
> didn't you send a v4 addressing that instead of resending the exact
> same v3?
The discussion between you and Stefan was in this thread:
http://patchwork.ozlabs.org/patch/689790/
Stefan proposed change, you replied with your concerns and that is all.
No clear decision what to change until today when Stefan prepared
separate (concise) patch (now I see what is the problem).
>
> Same goes for the regression introduced in patch 2: I think it's
> better to keep things bisectable on all platforms (even if it
> appeared to work by chance on imx7, it did work before this change).
Could you be more specific about your idea to solve this problem?
>
> That's just my opinion, but when you get reviews on a patch series,
> it's better to address them directly (especially when issues can be
> easily fixed) than provide follow-up patches.
I do not have iMX7 for testing/development, so I could not reproduce
the error and address the issue directly.
I can at best integrate Stefan's patch and hope to not introduce
regression.
Best regards,
Łukasz Majewski
>
> Regards,
>
> Boris
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next prev parent reply other threads:[~2016-12-29 16:55 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-23 21:45 [PATCH 0/6] pwm: imx: Provide atomic operation for IMX PWM driver Lukasz Majewski
2016-10-23 21:45 ` [PATCH 1/6] pwm: imx: Rewrite imx_pwm_*_v1 code to facilitate switch to atomic pwm operation Lukasz Majewski
2016-10-24 15:21 ` Boris Brezillon
2016-10-25 5:54 ` Sascha Hauer
2016-10-25 6:27 ` Boris Brezillon
2016-10-25 6:32 ` Sascha Hauer
2016-10-25 6:42 ` Boris Brezillon
2016-10-25 6:55 ` Lukasz Majewski
2016-10-23 21:45 ` [PATCH 2/6] pwm: imx: Move PWMv2 software reset code to a separate function Lukasz Majewski
2016-10-24 15:23 ` Boris Brezillon
2016-10-24 21:02 ` Lukasz Majewski
2016-10-23 21:45 ` [PATCH 3/6] pwm: imx: Move PWMv2 wait for fifo slot " Lukasz Majewski
2016-10-24 15:23 ` Boris Brezillon
2016-10-23 21:45 ` [PATCH 4/6] pwm: imx: Provide atomic PWM support for IMXv2 PWM Lukasz Majewski
2016-10-24 15:25 ` Boris Brezillon
2016-10-23 21:45 ` [PATCH 5/6] pwm: imx: Remove redundant IMX PWMv2 code Lukasz Majewski
2016-10-24 15:27 ` Boris Brezillon
2016-10-23 21:45 ` [PATCH 6/6] pwm: imx: Introduce "polarity_supported" flag to PWMv2 driver Lukasz Majewski
2016-10-24 15:28 ` Boris Brezillon
2016-10-24 15:34 ` Boris Brezillon
2016-10-24 21:14 ` Lukasz Majewski
2016-10-25 6:37 ` Boris Brezillon
2016-10-25 6:58 ` Lukasz Majewski
2016-10-24 15:36 ` [PATCH 0/6] pwm: imx: Provide atomic operation for IMX PWM driver Boris Brezillon
2016-10-24 21:26 ` Lukasz Majewski
2016-10-25 3:41 ` Stefan Agner
2016-10-25 7:07 ` Lukasz Majewski
2016-10-25 17:08 ` Fabio Estevam
2016-10-25 17:09 ` Fabio Estevam
2016-10-27 5:59 ` Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 00/11] " Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 01/11] pwm: print error messages with pr_err() instead of pr_debug() Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 02/11] pwm: imx: remove ipg clock Lukasz Majewski
2016-12-27 7:26 ` Stefan Agner
2016-12-27 7:54 ` Lukasz Majewski
2016-12-28 22:01 ` Lukasz Majewski
2016-12-29 7:22 ` Stefan Agner
2016-12-29 10:06 ` Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 03/11] pwm: imx: Add separate set of pwm ops for PWMv1 and PWMv2 Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 04/11] pwm: imx: Rewrite imx_pwm_*_v1 code to facilitate switch to atomic pwm operation Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 05/11] pwm: imx: Move PWMv2 software reset code to a separate function Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 06/11] pwm: imx: Move PWMv2 wait for fifo slot " Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 07/11] pwm: imx: Provide atomic PWM support for i.MX PWMv2 Lukasz Majewski
2016-12-29 16:21 ` Boris Brezillon
2016-12-29 16:45 ` Lukasz Majewski [this message]
2016-12-29 17:08 ` Boris Brezillon
2017-01-03 11:43 ` Lukasz Majewski
2017-01-03 12:46 ` Boris Brezillon
2017-01-03 17:29 ` Stefan Agner
2017-01-03 19:35 ` Boris Brezillon
2017-01-03 22:01 ` Lukasz Majewski
2017-01-03 22:18 ` Boris Brezillon
2017-01-03 22:46 ` Lukasz Majewski
2017-01-03 23:34 ` Boris Brezillon
2017-01-04 11:29 ` Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 08/11] pwm: imx: Remove redundant i.MX PWMv2 code Lukasz Majewski
2016-12-26 22:55 ` [PATCH v3 RESEND 09/11] pwm: core: make the PWM_POLARITY flag in DTB optional Lukasz Majewski
2016-12-26 22:56 ` [PATCH v3 RESEND 10/11] pwm: imx: doc: Update imx-pwm.txt documentation entry Lukasz Majewski
2016-12-26 22:56 ` [PATCH v3 RESEND 11/11] pwm: imx: Add polarity inversion support to i.MX's PWMv2 Lukasz Majewski
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