From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH v2 1/4] iio: adc: rockchip_saradc: reset saradc controller before programming it Date: Tue, 26 Jul 2016 19:00:18 -0700 Message-ID: <579815B2.5010205@roeck-us.net> References: <1469535195-5227-1-git-send-email-wxt@rock-chips.com> <57976814.3040605@roeck-us.net> <579777F4.2090002@rock-chips.com> <20160726170023.GA6590@roeck-us.net> <57980362.3000406@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <57980362.3000406-TNX95d0MmH7DzftRWevZcw@public.gmane.org> Sender: linux-iio-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Caesar Wang Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org, linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, john-HooS5bfzL4hWk0Htik3J/w@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org List-Id: devicetree@vger.kernel.org On 07/26/2016 05:42 PM, Caesar Wang wrote: > > On 2016=E5=B9=B407=E6=9C=8827=E6=97=A5 01:00, Guenter Roeck wrote: >> On Tue, Jul 26, 2016 at 10:47:16PM +0800, Caesar Wang wrote: >>> On 2016=E5=B9=B407=E6=9C=8826=E6=97=A5 21:39, Guenter Roeck wrote: >>>>> static int rockchip_saradc_probe(struct platform_device *pdev) >>>>> { >>>>> struct rockchip_saradc *info =3D NULL; >>>>> @@ -218,6 +231,21 @@ static int rockchip_saradc_probe(struct >>>>> platform_device *pdev) >>>>> if (IS_ERR(info->regs)) >>>>> return PTR_ERR(info->regs); >>>>> >>>>> + /* >>>>> + * The reset should be an optional property, as it should work >>>>> + * with old devicetrees as well >>>>> + */ >>>>> + info->reset =3D devm_reset_control_get_optional(&pdev->dev, >>>>> + "saradc-apb"); >>>> Does anyone know what the _optional API is for ? It seems to be ex= actly >>>> the same >>>> as devm_reset_control_get(). >>> =E2=80=9C >>> As far as I see, the difference is WARN_ON(1) >>> when CONFIG_RESET_CONTROLLER is not defined. >>> >>> >>> The _optional functions were introduced by the following commit: >>> >>> ----------------->8----------------- >>> commit b424080a9e086e683ad5fdc624a7cf3c024e0c0f >>> Author: Philipp Zabel >>> Date: Fri Mar 7 15:18:47 2014 +0100 >>> >>> reset: Add optional resets and stubs >>> >>> This patch adds device_reset_optional and (devm_)reset_control_get_= optional >>> variants that drivers can use to indicate they can function without= control >>> over the reset line. For those functions, stubs are added so the dr= ivers can >>> be compiled with CONFIG_RESET_CONTROLLER disabled. >>> Also, device_reset is annotated with __must_check. Drivers >>> ignoring the return >>> value should use device_reset_optional instead. >>> >> Is that really what we are looking for here ? CONFIG_RESET_CONTROLLE= R >> is required for other functions of rk3399, isn't it ? > > Right, as the DRM and thermal are depend on the CONFIG_RESET_CONTROLL= ER ..... > Since "optional" doesn't really mean "the reset property is optional" but "CONFIG_RESET_CONTROLLER is optional", I would suggest to use devm_reset_control_get(). Guenter