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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH autolearn=ham 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 CC3F2C4321A for ; Mon, 10 Jun 2019 23:40:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9DA492086A for ; Mon, 10 Jun 2019 23:40:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560210055; bh=mohPqaA8xgJOKhd1BCUCmxIzOCK/TYeC1MF6iHiSzxI=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=dgzXHIq5clFgl6v9XZzjIbttLOkuvoA6SlqI77PlBdLOIMt3SwUFE0j++xLoqvj7U +AfzKJV6zwY2OxCNqqs4Hmz01+OKhkKlqwpl+9HFl75EAriAKJMmHZvR0fRemeFgRG Y+x89M3ndub0/eLWoHYS/ZUFIcKW0KCOzM6hglXw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390656AbfFJXkz (ORCPT ); Mon, 10 Jun 2019 19:40:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:47160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390524AbfFJXkz (ORCPT ); Mon, 10 Jun 2019 19:40:55 -0400 Received: from [192.168.1.32] (cpe-70-114-128-244.austin.res.rr.com [70.114.128.244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A2B99206C3; Mon, 10 Jun 2019 23:40:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560210054; bh=mohPqaA8xgJOKhd1BCUCmxIzOCK/TYeC1MF6iHiSzxI=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=zuXphXcAgY/HWNpIsAFzmqLpCu62zF5beO+Je5IGz0a22zRZ8b29uozbR4DezKxWP ll7swaszkCOrBVpWhJ2KvdFMnCITcl9omdycyvXHF2+siCHtQq7Y+KOMBR3s0EHXaL 9vxOXqgdwh/JjI9Jhh4i5YerLRYpun3n+yhaGeO8= Subject: Re: [PATCH 2/2] dmagengine: pl330: add code to get reset property To: Geert Uytterhoeven Cc: Vinod Koul , dmaengine@vger.kernel.org, Rob Herring , Mark Rutland , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" References: <20190524002847.30961-1-dinguyen@kernel.org> <20190524002847.30961-2-dinguyen@kernel.org> <20190604121424.GW15118@vkoul-mobl> <1dd97825-f6a2-7a1b-33ef-e28e00cc8506@kernel.org> <00841780-ad68-ba8d-bdf0-d3f78fa42c98@kernel.org> <55cc6016-f297-539d-df08-777903b79005@kernel.org> From: Dinh Nguyen Openpgp: preference=signencrypt Autocrypt: addr=dinguyen@kernel.org; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Hi Geert, On 6/7/19 2:37 AM, Geert Uytterhoeven wrote: > Hi Dinh, > > On Wed, Jun 5, 2019 at 5:31 PM Dinh Nguyen wrote: >> On 6/5/19 9:41 AM, Dinh Nguyen wrote: >>> On 6/4/19 11:31 AM, Geert Uytterhoeven wrote: >>>> On Tue, Jun 4, 2019 at 4:21 PM Dinh Nguyen wrote: >>>>> On 6/4/19 7:14 AM, Vinod Koul wrote: >>>>>> On 23-05-19, 19:28, Dinh Nguyen wrote: >>>>>>> The DMA controller on some SoCs can be held in reset, and thus requires >>>>>>> the reset signal(s) to deasserted. Most SoCs will have just one reset >>>>>>> signal, but there are others, i.e. Arria10/Stratix10 will have an >>>>>>> additional reset signal, referred to as the OCP. >>>>>>> >>>>>>> Add code to get the reset property from the device tree for deassert and >>>>>>> assert. >>>>>>> >>>>>>> Signed-off-by: Dinh Nguyen > >>>>>>> --- a/drivers/dma/pl330.c >>>>>>> +++ b/drivers/dma/pl330.c > >>>>>>> @@ -3028,6 +3032,30 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id) >>>>>>> >>>>>>> amba_set_drvdata(adev, pl330); >>>>>>> >>>>>>> + pl330->rstc = devm_reset_control_get_optional(&adev->dev, "dma"); >>>>>>> + if (IS_ERR(pl330->rstc)) { >>>>>>> + dev_err(&adev->dev, "No reset controller specified.\n"); > > "No reset controller specified.\n" > >>>>>> >>>>>> Wasnt this optional?? >>>>> >>>>> Yes, this is optional. The call devm_reset_control_get_optional() will >>>>> just return NULL if the reset property is not there, but an error >>>>> pointer if something really went wrong. Thus, I'm using IS_ERR() for the >>>>> error checking. >>>> >>>> So the error message is incorrect, as this is a real error condition? >>> >>> Yes, you're right! Will correct in V2. >> >> Looking at this again, I think the error message is correct. The >> optional call will return NULL if the resets property is not specified, >> and will return an error pointer if the reset propert is specified, but >> the pointer to the reset controller is not found. >> >> So I think the error message is correct. > > Please reread the error message, and what you wrote above. > > Error message: "No reset controller specified". > Rationale: NULL (i.e. no error) if "the resets property is not specified". > > If an error pointer is returned, this may be due to probe deferral (to be > propagated, but further ignored), or due to a real failure. > > So IMHO the code should read: > > if (IS_ERR(pl330->rstc)) { > if (PTR_ERR(pl330->rstc) != -EPROBE_DEFER) > dev_err(&adev->dev, "Failed to get reset.\n"); > return PTR_ERR(pl330->rstc); > } else { ... } > You're right! Will update in v2. Thanks! Dinh