From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Looijmans Subject: Re: [PATCH] sdhci: Forward EPROBE_DEFER on vmmc and vqmmc regulators Date: Mon, 7 Apr 2014 14:32:20 +0200 Message-ID: <53429AD4.7030508@topic.nl> References: <1395991817-3503-1-git-send-email-mike.looijmans@topic.nl> <5342971F.3010705@codethink.co.uk> <534297AE.1020907@codethink.co.uk> <10471336.Pb8zVvW3Hp@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp103.mer-nm.internl.net ([217.149.192.139]:58162 "EHLO smtp103.mer-nm.internl.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755161AbaDGMcZ convert rfc822-to-8bit (ORCPT ); Mon, 7 Apr 2014 08:32:25 -0400 In-Reply-To: <10471336.Pb8zVvW3Hp@wuerfel> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Arnd Bergmann , Ben Dooks Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, cjb@laptop.org, gdjakov@mm-sol.com =EF=BB=BFOn 04/07/2014 02:25 PM, Arnd Bergmann wrote: > On Monday 07 April 2014 13:18:54 Ben Dooks wrote: >> On 07/04/14 13:16, Ben Dooks wrote: >>> On 07/04/14 13:09, Mike Looijmans wrote: >>>> On 04/07/2014 10:11 AM, Arnd Bergmann wrote: >>>>> On Monday 07 April 2014 08:38:28 Mike Looijmans wrote: >>>>>> index 34aef81..43b90c1 100644 >>>>>> --- a/drivers/mmc/host/sdhci.c >>>>>> +++ b/drivers/mmc/host/sdhci.c >>>>>> @@ -2972,6 +2972,8 @@ int sdhci_add_host(struct sdhci_host *host= ) >>>>>> host->vqmmc =3D regulator_get_optional(mmc_dev(mmc), "= vqmmc"); >>>>>> if (IS_ERR_OR_NULL(host->vqmmc)) { >>>>>> if (PTR_ERR(host->vqmmc) < 0) { >>>>>> + if (PTR_ERR(host->vqmmc) =3D=3D -EPROBE_= DEFER) >>>>>> + return -EPROBE_DEFER; >>>>>> pr_info("%s: no vqmmc regulator found\= n", >>>>>> mmc_hostname(mmc)); >>>>>> host->vqmmc =3D NULL; >>>>>> @@ -3048,8 +3050,10 @@ int sdhci_add_host(struct sdhci_host *hos= t) >>>>>> host->vmmc =3D regulator_get_optional(mmc_dev(mmc), "v= mmc"); >>>>>> if (IS_ERR_OR_NULL(host->vmmc)) { >>>>>> if (PTR_ERR(host->vmmc) < 0) { >>>>>> - pr_info("%s: no vmmc regulator found\n", >>>>>> - mmc_hostname(mmc)); >>>>>> + if (PTR_ERR(host->vmmc) =3D=3D -EPROBE_D= EFER) >>>>>> + return -EPROBE_DEFER; >>>>>> + pr_info("%s: no vmmc regulator found (%d= )\n", >>>>>> + mmc_hostname(mmc), >>>>>> PTR_ERR(host->vmmc)); >>>>>> host->vmmc =3D NULL; >>>>>> } >>>>> >>>>> Please change the code to not use IS_ERR_OR_NULL() instead, getti= ng >>>>> a NULL return value from regulator_get_optional() should not be >>>>> considered a bug, while getting an error return should always >>>>> cause the probe function to fail. >>> >>> Surely it needs to be changed to IS_ERR(), nor IS_ERR_OR_NULL()? >> >> >> And by that, I mean the use of "PTR_ERR(host->vmmc) < 0" to be >> changed to IS_ERR(), which I think Arnd was originally complaining >> about. > > I mean something like > > host->vqmmc =3D regulator_get_optional(mmc_dev(mmc), "vqmmc"); > > if (IS_ERR(host->vqmmc)) { > if (PTR_ERR(host->vqmmc) !=3D -EPROBE_DEFER) > complain(); /* only print a message if we won't retry */ > return ERR_PTR(host->vqmmc); /* never ignore an error */ > } > /* silently continue if no regulator is defined */ > > regulator_get_optional() means we can continue if it's not there, but > we should not continue if there is a regulator that we fail to use > for some reason. > > As has been found a number of times, any use of IS_ERR_OR_NULL() > means that the person responsible for the code is confused about > what the API is supposed to be. Judging from the kernel output, regulator_get_optional returns -ENODEV = if the=20 supply wasn't found. Maybe the API is confusing (or wrong?) here. If you change the code as per your suggestion, the SD will not work unl= ess you=20 explicitly assign supplies. And judging from what I've seen so far, I a= m the=20 first to have ever attached a power supply to this controller... Mike. Met vriendelijke groet / kind regards, Mike Looijmans TOPIC Embedded Systems Eindhovenseweg 32-C, NL-5683 KH Best Postbus 440, NL-5680 AK Best Telefoon: (+31) (0) 499 33 69 79 Telefax: (+31) (0) 499 33 69 70 E-mail: mike.looijmans@topic.nl Website: www.topic.nl Please consider the environment before printing this e-mail Visit us at the Hannover Messe 7 - 11 April 2014 - Hall 002/D10 (Dutch = Pavillion) http://www.hannovermesse.de/exhibitor/topic-embedded-products/V229623