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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 15EADC43331 for ; Mon, 30 Mar 2020 22:04:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE45D20771 for ; Mon, 30 Mar 2020 22:03:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QlDnJ+HX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730836AbgC3WD6 (ORCPT ); Mon, 30 Mar 2020 18:03:58 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:40428 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729386AbgC3WD6 (ORCPT ); Mon, 30 Mar 2020 18:03:58 -0400 Received: by mail-pg1-f195.google.com with SMTP id t24so9334800pgj.7; Mon, 30 Mar 2020 15:03:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:subject:from:to:cc:date:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=Fn5bbEwDKA1CjrL2t4+buEZ5DMdOn8ZLIb0ux0e5B3Q=; b=QlDnJ+HXQj0YHxnX8aX313kM6rHoKORnaNm2WYXDMn1aeXXbnF8UNEQ4VowdZeG4zl uV2sLQkwXOtnNAwFLkHNHrGIdHbHg2WXKZ+OCxvcK6XGQ4p7XyOtNEZguQcao8eEbZik jzhJzwgxyju9KgyIAO6AGWgfZzTJEGj7PCStu/3VWR74BEj6493pWtlmOVLr3PXjMy6j EvPvcs8zuq5fFUGMmdyzRW3LnvxqECq4R5074NxZe/sQXvq3wyUHonW+iSMHkNnpBI2D MA52ER9NNMOOvvHw75Dyrr3HHU19n2Cm6kVIde2BUnl4kJPuV5rqVxtOQP/DKfiUAQTz Rlnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=Fn5bbEwDKA1CjrL2t4+buEZ5DMdOn8ZLIb0ux0e5B3Q=; b=XlyaJQ75YmYZFlHYQ3CsRkt7hNrVdnNy1xCTwovTHU+C8ASxZAQbCcCI8UjYnILFma MoF/XvJ3SWBj4nXIQxoZkOvKzMYAfQfO1BBMUzGACPklifq9Weu6pCCOSkL9C5b6MvcP ZxWP5cb6998V5c2kOTtHtDSj8YYijRKZ136kQ0QXOx1nKOhQrRI8RJH6ngcAcQnA6h2d UtlTaR1RIYc6WEcWXpzh7E8kn5zVf+h/7BZq+gmKkzqkCSWgVk8ePKokzRw5O2GqGpTs TYSbj9ap8KTJJwiQxmXVKpOVV+wIjbZmFvAsthINGHVLlU/NcDYV+7m3T5NKiATY37rC HdVg== X-Gm-Message-State: AGi0Puapi+qiYG6iLMKtdCei6VgfebfVrffPlu6r8GYItW73WV4tcK9t 0zIWT4Y9QKhek/pehQzNyRtRRQg//G3+tg== X-Google-Smtp-Source: APiQypIZ7rugn26VNzMH9f1FGurreUtTRDwMeVEoQLstiLOtdeGMyyyqnQhROZmrQSttmeLztEHYWg== X-Received: by 2002:a65:55c6:: with SMTP id k6mr1200130pgs.52.1585605836849; Mon, 30 Mar 2020 15:03:56 -0700 (PDT) Received: from OptiPlexFedora ([47.144.161.84]) by smtp.gmail.com with ESMTPSA id h4sm1230719pgg.67.2020.03.30.15.03.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Mar 2020 15:03:56 -0700 (PDT) Message-ID: <53befe00af657428b591200b31b5349a4a462eb1.camel@gmail.com> Subject: Re: [Outreachy kernel] [PATCH] staging: fbtft: Replace udelay with preferred usleep_range From: "John B. Wyatt IV" To: Stefano Brivio Cc: Julia Lawall , Soumyajit Deb , outreachy-kernel@googlegroups.com, Greg Kroah-Hartman , Payal Kshirsagar , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Date: Mon, 30 Mar 2020 15:03:55 -0700 In-Reply-To: <20200330194043.56c79bb8@elisabeth> References: <20200329092204.770405-1-jbwyatt4@gmail.com> <2fccf96c3754e6319797a10856e438e023f734a7.camel@gmail.com> <20200330194043.56c79bb8@elisabeth> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2020-03-30 at 19:40 +0200, Stefano Brivio wrote: > On Sun, 29 Mar 2020 12:37:18 +0200 (CEST) > Julia Lawall wrote: > > > On Sun, 29 Mar 2020, Soumyajit Deb wrote: > > > > > I had the same doubt the other day about the replacement of > > > udelay() with > > > usleep_range(). The corresponding range for the single argument > > > value of > > > udelay() is quite confusing as I couldn't decide the range. But > > > as much as I > > > noticed checkpatch.pl gives warning for replacing udelay() with > > > usleep_range() by checking the argument value of udelay(). In the > > > documentation, it is written udelay() should be used for a sleep > > > time of at > > > most 10 microseconds but between 10 microseconds and 20 > > > milliseconds, > > > usleep_range() should be used. > > > I think the range is code specific and will depend on what range > > > is > > > acceptable and doesn't break the code. > > > Please correct me if I am wrong. > > > > The range depends on the associated hardware. > > John, by the way, here you could have checked the datasheet of this > LCD > controller. It's a pair of those: > https://www.sparkfun.com/datasheets/LCD/ks0108b.pdf > No I have not. This datasheet is a little over my head honestly. What would you recommend to get familiar with datasheets like this?