From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5473FC433E6 for ; Fri, 5 Mar 2021 15:34:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17B0C6509B for ; Fri, 5 Mar 2021 15:34:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230150AbhCEPde (ORCPT ); Fri, 5 Mar 2021 10:33:34 -0500 Received: from netrider.rowland.org ([192.131.102.5]:42317 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S230109AbhCEPdN (ORCPT ); Fri, 5 Mar 2021 10:33:13 -0500 Received: (qmail 39139 invoked by uid 1000); 5 Mar 2021 10:33:12 -0500 Date: Fri, 5 Mar 2021 10:33:12 -0500 From: Alan Stern To: Chunfeng Yun Cc: Mathias Nyman , Greg Kroah-Hartman , Ikjoon Jang , Matthias Brugger , linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, Nicolas Boichat , Eddie Hung Subject: Re: [PATCH 16/17] usb: common: add function to get interval expressed in us unit Message-ID: <20210305153312.GA38200@rowland.harvard.edu> References: <1614934975-15188-1-git-send-email-chunfeng.yun@mediatek.com> <1614934975-15188-16-git-send-email-chunfeng.yun@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1614934975-15188-16-git-send-email-chunfeng.yun@mediatek.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 05, 2021 at 05:02:54PM +0800, Chunfeng Yun wrote: > Add a new function to convert bInterval into the time expressed > in 1us unit. > > Signed-off-by: Chunfeng Yun > --- > --- a/drivers/usb/common/common.c > +++ b/drivers/usb/common/common.c > @@ -165,6 +165,39 @@ enum usb_dr_mode usb_get_dr_mode(struct device *dev) > } > EXPORT_SYMBOL_GPL(usb_get_dr_mode); > > +unsigned int usb_decode_interval(const struct usb_endpoint_descriptor *epd, > + enum usb_device_speed speed) > +{ > + unsigned int interval = 0; > + > + switch (usb_endpoint_type(epd)) { > + case USB_ENDPOINT_XFER_CONTROL: > + /* uframes per NAK */ > + if (speed == USB_SPEED_HIGH) > + interval = epd->bInterval; > + break; > + case USB_ENDPOINT_XFER_ISOC: > + interval = 1 << (epd->bInterval - 1); > + break; > + case USB_ENDPOINT_XFER_BULK: > + /* uframes per NAK */ > + if (speed == USB_SPEED_HIGH && usb_endpoint_dir_out(epd)) > + interval = epd->bInterval; > + break; > + case USB_ENDPOINT_XFER_INT: > + if (speed >= USB_SPEED_HIGH) > + interval = 1 << (epd->bInterval - 1); > + else > + interval = epd->bInterval; > + break; > + } > + > + interval *= (speed >= USB_SPEED_HIGH) ? 125 : 1000; > + > + return interval; > +} > +EXPORT_SYMBOL_GPL(usb_decode_interval); > --- a/include/linux/usb/ch9.h > +++ b/include/linux/usb/ch9.h > @@ -90,6 +90,17 @@ extern enum usb_ssp_rate usb_get_maximum_ssp_rate(struct device *dev); > */ > extern const char *usb_state_string(enum usb_device_state state); > > +/** > + * usb_decode_interval - Decode bInterval into the time expressed in 1us unit > + * @epd: The descriptor of the endpoint > + * @speed: The speed that the endpoint works as > + * > + * Function returns the interval expressed in 1us unit for servicing > + * endpoint for data transfers. > + */ > +unsigned int usb_decode_interval(const struct usb_endpoint_descriptor *epd, > + enum usb_device_speed speed); As a general rule, I believe people expect to find the kerneldoc for a function next to the function's definition, not next to the declaration in a header file. Alan Stern