linux-kernel - Re: [PATCH 6/6] pwm: imx: Introduce "polarity

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Date:   Mon, 24 Oct 2016 17:34:10 +0200
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Lukasz Majewski <l.majewski@...ess.pl>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Stefan Agner <stefan@...er.ch>, linux-pwm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Fabio Estevam <fabio.estevam@....com>,
        Fabio Estevam <festevam@...il.com>,
        Lothar Wassmann <LW@...o-electronics.de>,
        Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>,
        kernel@...gutronix.de
Subject: Re: [PATCH 6/6] pwm: imx: Introduce "polarity_supported" flag to
 PWMv2 driver

On Mon, 24 Oct 2016 17:28:52 +0200
Boris Brezillon <boris.brezillon@...e-electrons.com> wrote:

> On Sun, 23 Oct 2016 23:45:46 +0200
> Lukasz Majewski <l.majewski@...ess.pl> wrote:
> 
> > The need for set_polarity() function has been removed by implementing
> > PWM atomic support (apply() callback).
> > 
> > To indicate that the PWMv2 supports polarity inversion, new flag -
> > "polarity_supported" has been introduced.
> > 
> > Signed-off-by: Lukasz Majewski <l.majewski@...ess.pl>
> > ---
> >  drivers/pwm/pwm-imx.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
> > index 02d3dfd..be3034d 100644
> > --- a/drivers/pwm/pwm-imx.c
> > +++ b/drivers/pwm/pwm-imx.c
> > @@ -258,6 +258,7 @@ static struct pwm_ops imx_pwm_ops_v2 = {
> >  };
> >  
> >  struct imx_pwm_data {
> > +	bool polarity_supported;
> >  	struct pwm_ops *pwm_ops;
> >  };
> >  
> > @@ -266,6 +267,7 @@ static struct imx_pwm_data imx_pwm_data_v1 = {
> >  };
> >  
> >  static struct imx_pwm_data imx_pwm_data_v2 = {
> > +	.polarity_supported = true,
> >  	.pwm_ops = &imx_pwm_ops_v2,
> >  };
> >  
> > @@ -313,7 +315,7 @@ static int imx_pwm_probe(struct platform_device *pdev)
> >  	imx->chip.base = -1;
> >  	imx->chip.npwm = 1;
> >  	imx->chip.can_sleep = true;
> > -	if (data->pwm_ops->set_polarity) {
> > +	if (data->polarity_supported) {  
> 
> You're still breaking backward compatibility with DTs defining
> #pwm-cells = 2.
> 
> Please test the #pwm-cells value before deciding which of_xlate should
> be used.

Nevermind, I didn't look at [1] and [2].
But still, your series is not bisectable: this change should be part of
patch 5 where you remove the ->set_polarity implementation. Otherwise,
this means you don't support polarity setting between patch 5 and 6.

> 
> >  		dev_dbg(&pdev->dev, "PWM supports output inversion\n");
> >  		imx->chip.of_xlate = of_pwm_xlate_with_flags;
> >  		imx->chip.of_pwm_n_cells = 3;  
> 

[1]http://patchwork.ozlabs.org/patch/679706/
[2]http://patchwork.ozlabs.org/patch/679707/