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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 AEF2AC433E0 for ; Fri, 29 May 2020 17:12:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 897AD20723 for ; Fri, 29 May 2020 17:12:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590772358; bh=pWdiLQKXlqkVWGFk1vwAA7pmGBuWEqo3AyBqWZl5aR8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=KHMP4jK7M8U0tHMwjzjjBCjEa3XnjeF6Cdf0yV17U0BisvCFQluQM0ynPsofhiibW lJG2Lv3U6btosFFjK8WPgzJzRoHCZRm4OnEANqrh8sTDUXpGGutTVs/QAboSDj4TCe Y31G68rQABxiiDEllFi9nruPegFM0GdMqdYiKrck= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726555AbgE2RMe (ORCPT ); Fri, 29 May 2020 13:12:34 -0400 Received: from mail-il1-f195.google.com ([209.85.166.195]:34777 "EHLO mail-il1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725601AbgE2RMe (ORCPT ); Fri, 29 May 2020 13:12:34 -0400 Received: by mail-il1-f195.google.com with SMTP id v11so3254165ilh.1; Fri, 29 May 2020 10:12:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=bx0PYvSq6NXKj78JIhFRx0Ln0MPRytiQWRFm69j6/II=; b=FibTTiAXPZA8ncGPD15f56t67fVXt50ryXvQcrpouWAHMUzjDv1nMYHkF8ZGH+wVdn lP14S8UMxjKZFQGJwccUuGIXrooQgj6fpD9KP4UafcYLcp97mY6mYYWdI5D24Df24vcI i2Qwc4bsxEE65hccxWAMsxMwDZSx1WWFbTQM4JlwiTcYlr6mqvk3kQWUNPeXH5xE7uPn WbCSp3T2YAWb3ubnf55t0qnblXtog/VpwZjXVcH48RkZOgohLlbVNpYTDjDOPMmZ5nP6 OKkrSNQzNDO+fE+dCyO/4Y4IA9sIj14sKf/TR4c2OiUQ/Lew6C2gmKMddtewRzhrWPIF sAkQ== X-Gm-Message-State: AOAM530gtSvSuqwlMUSxONSPxXWq1p9YGfgjZlaoGaEnSquTtC2pFdG+ mSudf7criqDAqRjS/3Gn6g== X-Google-Smtp-Source: ABdhPJx3pelBzqI23xyZAGyODV+mdjrDEnHa6vJcIHqwehHVDJoZHGYIfuPjm8tPctXXxT9q75pF9A== X-Received: by 2002:a92:5b15:: with SMTP id p21mr7028596ilb.22.1590772353030; Fri, 29 May 2020 10:12:33 -0700 (PDT) Received: from xps15 ([64.188.179.252]) by smtp.gmail.com with ESMTPSA id v13sm5199788ili.15.2020.05.29.10.12.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 May 2020 10:12:32 -0700 (PDT) Received: (nullmailer pid 2586805 invoked by uid 1000); Fri, 29 May 2020 17:12:31 -0000 Date: Fri, 29 May 2020 11:12:31 -0600 From: Rob Herring To: Arnd Bergmann Cc: Olivier Sobrie , Matt Mackall , Herbert Xu , Greg Kroah-Hartman , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , DTML , "linux-kernel@vger.kernel.org" , Waleed Ziad , sebastien.rabou@silexinsight.com Subject: Re: [PATCH 3/3] hwrng: ba431-rng: add support for BA431 hwrng Message-ID: <20200529171231.GA2581035@bogus> References: <20200525195606.2941649-1-olivier.sobrie@silexinsight.com> <20200525195606.2941649-4-olivier.sobrie@silexinsight.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Mon, May 25, 2020 at 10:28:46PM +0200, Arnd Bergmann wrote: > On Mon, May 25, 2020 at 10:07 PM Olivier Sobrie > wrote: > > > > Silex insight BA431 is an IP designed to generate random numbers that > > can be integrated in various FPGA. > > This driver adds support for it through the hwrng interface. > > > > This driver is used in Silex Insight Viper OEM boards. > > > > Signed-off-by: Olivier Sobrie > > Signed-off-by: Waleed Ziad > > The driver looks good to me. > > Acked-by: Arnd Bergmann > > > drivers/char/hw_random/Kconfig | 10 ++ > > drivers/char/hw_random/Makefile | 1 + > > drivers/char/hw_random/ba431-rng.c | 240 +++++++++++++++++++++++++++++ > > I wonder if we should move drivers/char/hw_random to its own top-level drivers > subsystem outside of drivers/char. It seems to be growing steadily and is larger > than a lot of other subsystems with currently 34 drivers in there. > > Not your problem though. > > > + /* Wait until the state changed */ > > + for (i = 0; i < BA431_RESET_READ_STATUS_RETRIES; ++i) { > > + state = ba431_trng_get_state(ba431); > > + if (state >= BA431_STATE_STARTUP) > > + break; > > + > > + udelay(BA431_RESET_READ_STATUS_INTERVAL); > > + } > > Looking for something to improve, I noticed that this loop can take over > a millisecond to time out, and it always runs in non-atomic context. > It may be better to use usleep_range() than udelay(). Or better yet, use the register polling helpers. Rob