From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753284AbdJTMIk (ORCPT ); Fri, 20 Oct 2017 08:08:40 -0400 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:45343 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752944AbdJTMIi (ORCPT ); Fri, 20 Oct 2017 08:08:38 -0400 Message-ID: <1508501313.7455.4.camel@pengutronix.de> Subject: Re: [PATCH v8] usb: dwc3: of-simple: Add support to get resets for the device From: Philipp Zabel To: Manu Gautam , linux-usb@vger.kernel.org Cc: Felipe Balbi , Vivek Gautam , linux-kernel@vger.kernel.org, kernel@pengutronix.de Date: Fri, 20 Oct 2017 14:08:33 +0200 In-Reply-To: <4410e062-f874-993d-d390-6996321d77cc@codeaurora.org> References: <20171019114743.2966-1-p.zabel@pengutronix.de> <4410e062-f874-993d-d390-6996321d77cc@codeaurora.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:3ad5:47ff:feaf:1a17 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2017-10-20 at 17:10 +0530, Manu Gautam wrote: > Hi, > > > On 10/19/2017 5:17 PM, Philipp Zabel wrote: > > From: Vivek Gautam > > > > Add support to get a list of resets available for the device. > > These resets must be kept de-asserted until the device is > > in use. > > > > Signed-off-by: Vivek Gautam > > [p.zabel@pengutronix.de: switch to hidden reset control array] > > Signed-off-by: Philipp Zabel > > --- > > v7: Rebased onto git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb.git testing/next > > --- > > drivers/usb/dwc3/dwc3-of-simple.c | 27 +++++++++++++++++++++++++-- > > 1 file changed, 25 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c > > index e129c32780818..ceea1619f8aa3 100644 > > --- a/drivers/usb/dwc3/dwc3-of-simple.c > > +++ b/drivers/usb/dwc3/dwc3-of-simple.c > > @@ -28,11 +28,13 @@ > > #include > > #include > > #include > > +#include > > > > struct dwc3_of_simple { > > struct device *dev; > > struct clk **clks; > > int num_clocks; > > + struct reset_control *resets; > > }; > > > > static int dwc3_of_simple_clk_init(struct dwc3_of_simple *simple, int count) > > @@ -95,10 +97,21 @@ static int dwc3_of_simple_probe(struct platform_device *pdev) > > platform_set_drvdata(pdev, simple); > > simple->dev = dev; > > > > + simple->resets = of_reset_control_array_get_optional_exclusive(np); > > + if (IS_ERR(simple->resets)) { > > + ret = PTR_ERR(simple->resets); > > + dev_err(dev, "failed to get device resets, err=%d\n", ret); > > + return ret; > > + } > > + > > + ret = reset_control_deassert(simple->resets); > > + if (ret) > > + goto err_resetc_put; > > + > > Are these reset signals asserted by default after power on? > I think correct way to handle this should be to have explicit reset_control_assert > before deassert. I can only assume. If the resets can be initially deasserted (for example because a bootloader may leave them in this state) and it is critical for the device internal state to be reset for the driver to function, the control should be asserted explicitly. regards Philipp