From: Lukasz Majewski <l.majewski@majess.pl>
To: Stefan Agner <stefan@agner.ch>
Cc: Thierry Reding <thierry.reding@gmail.com>,
Sascha Hauer <s.hauer@pengutronix.de>,
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>,
Boris Brezillon <boris.brezillon@free-electrons.com>,
Lothar Wassmann <LW@karo-electronics.de>,
kernel@pengutronix.de, Philipp Zabel <p.zabel@pengutronix.de>
Subject: Re: [PATCH v3 RESEND 02/11] pwm: imx: remove ipg clock
Date: Thu, 29 Dec 2016 11:06:24 +0100 [thread overview]
Message-ID: <20161229110624.3544a7dd@jawa> (raw)
In-Reply-To: <9c77756a3a4a88664d070f27291fba3f@agner.ch>
[-- Attachment #1: Type: text/plain, Size: 5581 bytes --]
Hi Stefan,
> On 2016-12-28 23:01, Lukasz Majewski wrote:
> > Hi Stefan,
> >
> >> Hi Stefan,
> >>
> >> > On 2016-12-26 23:55, Lukasz Majewski wrote:
> >> > > From: Sascha Hauer <s.hauer@pengutronix.de>
> >> > >
> >> > > The use of the ipg clock was introduced with commit
> >> > > 7b27c160c681 ("pwm: i.MX: fix clock lookup").
> >> > > In the commit message it was claimed that the ipg clock is
> >> > > enabled for register accesses. This is true for the ->config()
> >> > > callback, but not for the ->set_enable() callback. Given that
> >> > > the ipg clock is not consistently enabled for all register
> >> > > accesses we can assume that either it is not required at all
> >> > > or that the current code does not work. Remove the ipg clock
> >> > > code for now so that it's no longer in the way of refactoring
> >> > > the driver.
> >> >
> >> > Hi Lukasz,
> >> >
> >> > Has my concern addressed in any way with this resend?
> >> > https://lkml.org/lkml/2016/11/22/729
> >>
> >> Unfortunately not, since I don't have iMX7 for testing.
> >>
> >> >
> >> > Breaking hardware is usually not an option :-)
> >>
> >> Yes, I know, but
> >>
> >> Please look on the patch set from my perspective:
> >>
> >> I originally wanted to add polarity inversion to PWM. Then, there
> >> was the request from you and Boris to go with "atomicity" support,
> >> so I converted the driver to support it.
> >>
> >> This patch set has been resent on purpose at the end of merge
> >> window, so we do have some time to fix it if it would be accepted
> >> to -next tree (or any other PWM related one). Moreover, the burden
> >> for preparing patches would be smaller - since we all have agreed
> >> that "atomicity" is a more than welcome feature.
> >>
> >>
> >> >
> >> > I checked the i.MX 7 reference manual again, and in this case the
> >> > peripheral access clock is a clock line named "ipg_clk_s" (Table
> >> > 12-20), with a clock root "PWM1_CLK_ROOT" (Table 5-12). In i.MX 7
> >> > all clocks are behind a single gate, so in fact it does not
> >> > matter which clock we take. Given that others have peripheral
> >> > access behind the "pwm" gate, I guess we should take the "pwm"
> >> > gate...
> >>
> >>
> >> If possible please prepare a patch. It would be the best solution.
> >
> > If I might ask - are you willing to prepare patch to fix iMX7 or
> > shall I roll back to the ipg code already present in main line ?
>
> I doubt that just rolling back the existing code works for the new
> atomic change... I guess we have to really introduce a clk enable on
> each register access, also for the new atomic code.
Maybe this is a way to go.
>
> Not sure if we should fold this change in a existing commit or create
> a new patch ontop of your changes. The latter is probably easier,
I would opt for creating (adding) changes on top of my changes.
> but
> creates a "window of brokenness" for i.MX 7 in git history. But then,
> I don't really mind since it currently works more or less by chance...
Hmm... it seems like Sascha patch (included to the patch series):
http://patchwork.ozlabs.org/patch/708847/
is a good starting point (at least we removed ipg clock) for fixing
things.
>
> I can prepare a patch.
Thank you :-)
Best regards,
Łukasz Majewski
>
> --
> Stefan
>
> >
> >
> > Best regards,
> > Łukasz Majewski
> >
> >>
> >> Thanks in advance,
> >> Łukasz Majewski
> >>
> >> >
> >> > --
> >> > Stefan
> >> >
> >> > >
> >> > > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> >> > > Cc: Philipp Zabel <p.zabel@pengutronix.de>
> >> > > ---
> >> > > [commit message text refactored by Lukasz Majewski
> >> > > <l.majewski@majess.pl>] ---
> >> > > Changes for v3:
> >> > > - New patch
> >> > > ---
> >> > > drivers/pwm/pwm-imx.c | 19 +------------------
> >> > > 1 file changed, 1 insertion(+), 18 deletions(-)
> >> > >
> >> > > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> >> > > index d600fd5..70609ef2 100644
> >> > > --- a/drivers/pwm/pwm-imx.c
> >> > > +++ b/drivers/pwm/pwm-imx.c
> >> > > @@ -49,7 +49,6 @@
> >> > >
> >> > > struct imx_chip {
> >> > > struct clk *clk_per;
> >> > > - struct clk *clk_ipg;
> >> > >
> >> > > void __iomem *mmio_base;
> >> > >
> >> > > @@ -204,17 +203,8 @@ static int imx_pwm_config(struct pwm_chip
> >> > > *chip, struct pwm_device *pwm, int duty_ns, int period_ns)
> >> > > {
> >> > > struct imx_chip *imx = to_imx_chip(chip);
> >> > > - int ret;
> >> > > -
> >> > > - ret = clk_prepare_enable(imx->clk_ipg);
> >> > > - if (ret)
> >> > > - return ret;
> >> > >
> >> > > - ret = imx->config(chip, pwm, duty_ns, period_ns);
> >> > > -
> >> > > - clk_disable_unprepare(imx->clk_ipg);
> >> > > -
> >> > > - return ret;
> >> > > + return imx->config(chip, pwm, duty_ns, period_ns);
> >> > > }
> >> > >
> >> > > static int imx_pwm_enable(struct pwm_chip *chip, struct
> >> > > pwm_device *pwm) @@ -293,13 +283,6 @@ static int
> >> > > imx_pwm_probe(struct platform_device *pdev) return
> >> > > PTR_ERR(imx->clk_per); }
> >> > >
> >> > > - imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
> >> > > - if (IS_ERR(imx->clk_ipg)) {
> >> > > - dev_err(&pdev->dev, "getting ipg clock failed
> >> > > with %ld\n",
> >> > > - PTR_ERR(imx->clk_ipg));
> >> > > - return PTR_ERR(imx->clk_ipg);
> >> > > - }
> >> > > -
> >> > > imx->chip.ops = &imx_pwm_ops;
> >> > > imx->chip.dev = &pdev->dev;
> >> > > imx->chip.base = -1;
> >>
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next prev parent reply other threads:[~2016-12-29 14:55 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 [this message]
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
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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