From: Maxime Ripard <mripard@kernel.org>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: "Jernej Škrabec" <jernej.skrabec@siol.net>,
mark.rutland@arm.com, linux-pwm@vger.kernel.org,
devicetree@vger.kernel.org, linux-sunxi@googlegroups.com,
linux-kernel@vger.kernel.org, wens@csie.org, robh+dt@kernel.org,
thierry.reding@gmail.com, kernel@pengutronix.de,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/6] pwm: sun4i: Add a quirk for bus clock
Date: Mon, 29 Jul 2019 18:45:16 +0200 [thread overview]
Message-ID: <20190729164516.yxfgj2zd3d5ii4c4@flea.home> (raw)
In-Reply-To: <20190729161435.5bnj3ikocsyep4dd@pengutronix.de>
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On Mon, Jul 29, 2019 at 06:14:35PM +0200, Uwe Kleine-König wrote:
> Hello Jernej,
>
> On Mon, Jul 29, 2019 at 05:48:36PM +0200, Jernej Škrabec wrote:
> > Dne ponedeljek, 29. julij 2019 ob 08:38:25 CEST je Uwe Kleine-König
> > napisal(a):
> > > Hello,
> > >
> > > On Fri, Jul 26, 2019 at 08:40:42PM +0200, Jernej Skrabec wrote:
> > > > H6 PWM core needs bus clock to be enabled in order to work.
> > > >
> > > > Add a quirk for it.
> > > >
> > > > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > > > ---
> > > >
> > > > drivers/pwm/pwm-sun4i.c | 15 +++++++++++++++
> > > > 1 file changed, 15 insertions(+)
> > > >
> > > > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
> > > > index 1b7be8fbde86..7d3ac3f2dc3f 100644
> > > > --- a/drivers/pwm/pwm-sun4i.c
> > > > +++ b/drivers/pwm/pwm-sun4i.c
> > > > @@ -72,6 +72,7 @@ static const u32 prescaler_table[] = {
> > > >
> > > > };
> > > >
> > > > struct sun4i_pwm_data {
> > > >
> > > > + bool has_bus_clock;
> > > >
> > > > bool has_prescaler_bypass;
> > > > bool has_reset;
> > > > unsigned int npwm;
> > > >
> > > > @@ -79,6 +80,7 @@ struct sun4i_pwm_data {
> > > >
> > > > struct sun4i_pwm_chip {
> > > >
> > > > struct pwm_chip chip;
> > > >
> > > > + struct clk *bus_clk;
> > > >
> > > > struct clk *clk;
> > > > struct reset_control *rst;
> > > > void __iomem *base;
> > > >
> > > > @@ -382,6 +384,16 @@ static int sun4i_pwm_probe(struct platform_device
> > > > *pdev)>
> > > > reset_control_deassert(pwm->rst);
> > > >
> > > > }
> > > >
> > > > + if (pwm->data->has_bus_clock) {
> > > > + pwm->bus_clk = devm_clk_get(&pdev->dev, "bus");
> > >
> > > Similar to my suggestion in patch 2: I'd use devm_clk_get_optional() and
> > > drop struct sun4i_pwm_data::has_bus_clock.
> >
> > This one is not so simple. This patch has incorrect logic. Correct logic would
> > be to use "devm_clk_get(&pdev->dev, NULL)" for variants without bus clock as
> > it is done already and "devm_clk_get(&pdev->dev, "bus")" and
> > "devm_clk_get(&pdev->dev, "mod")" for variants with bus clock.
>
> Then maybe something like the following?:
>
> busclk = devm_clk_get_optional(..., "bus");
> modclk = devm_clk_get_optional(..., "mod");
>
> /*
> * old dtbs might have a single clock but no clock names. Fall
> * back to this for compatibility reasons.
> */
> if (!modclk) {
> modclk = devm_clk_get(..., NULL);
> }
Again, there's nothing optional about these clocks. You need a
particular set of clocks for a given generation, and a separate set of
them on another generation of SoCs.
It really isn't about DT validation. We're really making sure that the
device can be operational. It's as much of a validation step than
making sure we have mapped registers (reg), or an interrupt if we had
any.
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2019-07-29 16:45 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 18:40 [PATCH 0/6] pwm: sun4i: Add support for Allwinner H6 Jernej Skrabec
2019-07-26 18:40 ` [PATCH 1/6] dt-bindings: pwm: allwinner: Add H6 PWM description Jernej Skrabec
2019-07-27 10:42 ` Maxime Ripard
2019-07-26 18:40 ` [PATCH 2/6] pwm: sun4i: Add a quirk for reset line Jernej Skrabec
2019-07-27 10:42 ` Maxime Ripard
2019-07-29 6:36 ` Uwe Kleine-König
2019-07-29 6:43 ` Chen-Yu Tsai
2019-07-29 7:12 ` Uwe Kleine-König
2019-07-29 10:18 ` Philipp Zabel
2019-07-29 16:37 ` Maxime Ripard
2019-07-29 18:20 ` Uwe Kleine-König
2019-07-26 18:40 ` [PATCH 3/6] pwm: sun4i: Add a quirk for bus clock Jernej Skrabec
2019-07-27 10:46 ` Maxime Ripard
2019-07-27 14:15 ` Jernej Škrabec
2019-07-27 14:27 ` Chen-Yu Tsai
2019-07-29 6:38 ` Uwe Kleine-König
2019-07-29 15:48 ` Jernej Škrabec
2019-07-29 16:14 ` Uwe Kleine-König
2019-07-29 16:45 ` Maxime Ripard [this message]
2019-07-29 19:04 ` Uwe Kleine-König
2019-07-26 18:40 ` [PATCH 4/6] pwm: sun4i: Add support for H6 PWM Jernej Skrabec
2019-07-29 6:40 ` Uwe Kleine-König
2019-07-29 15:55 ` Jernej Škrabec
2019-07-29 16:07 ` Uwe Kleine-König
2019-07-29 16:09 ` [linux-sunxi] " Chen-Yu Tsai
2019-07-29 16:24 ` Uwe Kleine-König
2019-07-29 16:40 ` Jernej Škrabec
2019-07-29 18:40 ` Uwe Kleine-König
2019-07-29 18:46 ` Jernej Škrabec
2019-07-29 18:51 ` Uwe Kleine-König
2019-07-29 22:04 ` Jernej Škrabec
2019-07-30 8:09 ` Uwe Kleine-König
2019-07-30 8:32 ` Chen-Yu Tsai
2019-07-30 17:06 ` Maxime Ripard
2019-07-31 6:52 ` Uwe Kleine-König
2019-08-12 9:56 ` Maxime Ripard
2019-08-12 10:47 ` Uwe Kleine-König
2019-08-12 10:51 ` Jernej Škrabec
2019-07-26 18:40 ` [PATCH 5/6] pwm: sun4i: Add support to output source clock directly Jernej Skrabec
2019-07-27 10:50 ` Maxime Ripard
2019-07-27 14:28 ` Jernej Škrabec
2019-07-27 14:54 ` [linux-sunxi] " Chen-Yu Tsai
2019-07-29 7:06 ` Uwe Kleine-König
2019-07-29 16:16 ` Jernej Škrabec
2019-07-29 16:29 ` Uwe Kleine-König
2019-07-26 18:40 ` [PATCH 6/6] arm64: dts: allwinner: h6: Add PWM node Jernej Skrabec
2019-07-27 10:51 ` Maxime Ripard
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