From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [RFC PATCH 2/2] usb: Example for how to use device node at usb device driver Date: Fri, 08 Jan 2016 09:26:10 +0100 Message-ID: <4231421.FQCAATyWeB@wuerfel> References: <1452231864-11171-1-git-send-email-peter.chen@freescale.com> <1452231864-11171-3-git-send-email-peter.chen@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <1452231864-11171-3-git-send-email-peter.chen-KZfg59tc24xl57MIdRCFDg@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Peter Chen Cc: gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, balbi-l0cyMroinI0@public.gmane.org, valentin.longchamp-SkAbAL50j+5BDgjK7y7TUQ@public.gmane.org List-Id: devicetree@vger.kernel.org On Friday 08 January 2016 13:44:24 Peter Chen wrote: > + u32 duration_us = 0; > + of_property_read_u32(hdev->dev.of_node, "delay-duration-us", &duration_us); > + if (duration_us > 0) { > + usleep_range(duration_us, duration_us + 10); > + dev_info(&hdev->dev, "The delay is %d us\n", duration_us); > + } > + I think especially for an example, it would be better to use error checking and not initialize the variable: u32 duration_us; int ret; ... ret = of_property_read_u32(hdev->dev.of_node, "delay-duration-us", &duration_us); if (!ret && duration_us > 0) { ... } The effect is the same as the other one. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Fri, 08 Jan 2016 09:26:10 +0100 Subject: [RFC PATCH 2/2] usb: Example for how to use device node at usb device driver In-Reply-To: <1452231864-11171-3-git-send-email-peter.chen@freescale.com> References: <1452231864-11171-1-git-send-email-peter.chen@freescale.com> <1452231864-11171-3-git-send-email-peter.chen@freescale.com> Message-ID: <4231421.FQCAATyWeB@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Friday 08 January 2016 13:44:24 Peter Chen wrote: > + u32 duration_us = 0; > + of_property_read_u32(hdev->dev.of_node, "delay-duration-us", &duration_us); > + if (duration_us > 0) { > + usleep_range(duration_us, duration_us + 10); > + dev_info(&hdev->dev, "The delay is %d us\n", duration_us); > + } > + I think especially for an example, it would be better to use error checking and not initialize the variable: u32 duration_us; int ret; ... ret = of_property_read_u32(hdev->dev.of_node, "delay-duration-us", &duration_us); if (!ret && duration_us > 0) { ... } The effect is the same as the other one. Arnd