From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roland Stigge Subject: Re: [PATCH] gpio: of_get_named_gpio_flags() return -EPROBE_DEFER if GPIO not yet available Date: Mon, 18 Jun 2012 17:08:17 +0200 Message-ID: <4FDF4461.60707@antcom.de> References: <1339927893-8842-1-git-send-email-stigge@antcom.de> <4FDE8D27.6030508@wwwdotorg.org> <4FDEF293.9080305@antcom.de> <4FDF403E.9090302@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from antcom.de ([188.40.178.216]:36127 "EHLO chuck.antcom.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752558Ab2FRPIU (ORCPT ); Mon, 18 Jun 2012 11:08:20 -0400 In-Reply-To: <4FDF403E.9090302@wwwdotorg.org> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Stephen Warren Cc: cjb@laptop.org, grant.likely@secretlab.ca, rob.herring@calxeda.com, rmk+kernel@arm.linux.org.uk, ulf.hansson@stericsson.com, linus.walleij@linaro.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, aletes.xgr@gmail.com, linux-arm-kernel@lists.infradead.org On 06/18/2012 04:50 PM, Stephen Warren wrote: >> Can you please tell in which way the patch breaks those drivers? >> However, I can see that those drivers solved the same problem in a >> different way (deferring of_get_named_gpio(), via the sound init()). So >> they could be adjusted to take advantage of new -EPROBE_DEFER. > > The drivers I mentioned test the return code of of_get_named_gpio() to > see if it's -ENODEV, which means that DT property for that GPIO exists > but the driver for it isn't available yet, so the property can't be > parsed. In this case, the sound drivers defer their own probe. If > of_get_named_gpio() is modified to return -EPROBE_DEFER directly, then > it won't be returning -ENODEV, and hence the sound drivers' check for > -ENODEV won't fire, and hence the sound drivers will just continue their > probe assuming that the particular GPIOs are not present on the board > (since they are all optional, so anything other than an explicit > deferral error from of_get_named_gpio() is not treated as an error). > This will break sound on those platforms. Thanks for the hint! I previously also suspected sth. like this but didn't find it in v3.5-rc3. In broonie's sound.git for-next, I now finally found it. Should be easy to fix (replacing the if (... == -ENODEV) to -EPROBE_DEFER. Will you provide patches as signalled, of should I? Which branch would be the correct one to build on top? Thanks in advance, Roland