From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH 3/6] pwm: sun4i: Add a quirk for bus clock Date: Mon, 29 Jul 2019 18:45:16 +0200 Message-ID: <20190729164516.yxfgj2zd3d5ii4c4@flea.home> References: <20190726184045.14669-1-jernej.skrabec@siol.net> <20190726184045.14669-4-jernej.skrabec@siol.net> <20190729063825.wxfky6nswcru26g7@pengutronix.de> <4022372.WfP88Fa4Lu@jernej-laptop> <20190729161435.5bnj3ikocsyep4dd@pengutronix.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="szfghxy2ac5dvf2h" Return-path: Content-Disposition: inline In-Reply-To: <20190729161435.5bnj3ikocsyep4dd@pengutronix.de> Sender: linux-kernel-owner@vger.kernel.org To: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= Cc: Jernej =?utf-8?Q?=C5=A0krabec?= , 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 List-Id: devicetree@vger.kernel.org --szfghxy2ac5dvf2h Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 29, 2019 at 06:14:35PM +0200, Uwe Kleine-K=C3=B6nig wrote: > Hello Jernej, > > On Mon, Jul 29, 2019 at 05:48:36PM +0200, Jernej =C5=A0krabec wrote: > > Dne ponedeljek, 29. julij 2019 ob 08:38:25 CEST je Uwe Kleine-K=C3=B6nig > > 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 > > > > --- > > > > > > > > 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[] =3D { > > > > > > > > }; > > > > > > > > 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_dev= ice > > > > *pdev)> > > > > reset_control_deassert(pwm->rst); > > > > > > > > } > > > > > > > > + if (pwm->data->has_bus_clock) { > > > > + pwm->bus_clk =3D 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 logi= c would > > be to use "devm_clk_get(&pdev->dev, NULL)" for variants without bus clo= ck 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 =3D devm_clk_get_optional(..., "bus"); > modclk =3D 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 =3D 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 --szfghxy2ac5dvf2h Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRcEzekXsqa64kGDp7j7w1vZxhRxQUCXT8inAAKCRDj7w1vZxhR xfAvAQDPD/W10siMsbxXt0TnODSzxIn/7DF49wiKOuWZz6OwFwEAnwlydOCmRVBw 8J0s2aXuCVfbyJpDqk/FcreSk6jcPQE= =dYSs -----END PGP SIGNATURE----- --szfghxy2ac5dvf2h--