From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.bootlin.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fPmDT-00084J-9M for linux-mtd@lists.infradead.org; Mon, 04 Jun 2018 09:55:59 +0000 Date: Mon, 4 Jun 2018 11:55:43 +0200 From: Boris Brezillon To: Janusz Krzysztofik Cc: Richard Weinberger , H Hartley Sweeten , Tony Lindgren , linux-kernel@vger.kernel.org, Marek Vasut , Krzysztof Halasa , Shreeya Patel , Arvind Yadav , Brian Norris , David Woodhouse , linux-mtd@lists.infradead.org Subject: Re: [PATCH 5/6 v2] mtd: rawnand: ams-delta: use GPIO lookup table Message-ID: <20180604115543.3be75717@bbrezillon> In-Reply-To: <1582841.uoaVdad1fL@z50> References: <1543045.tPZatK9yHU@z50> <20180530195220.3527f0fc@bbrezillon> <1582841.uoaVdad1fL@z50> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 30 May 2018 22:39:03 +0200 Janusz Krzysztofik wrote: > On Wednesday, May 30, 2018 7:52:20 PM CEST Boris Brezillon wrote: > > On Wed, 30 May 2018 19:43:09 +0200 > > > > Janusz Krzysztofik wrote: > > > On Wednesday, May 30, 2018 11:05:00 AM CEST Boris Brezillon wrote: > > > > Hi Janusz, > > > > > > Hi Boris, > > > > > > > On Sat, 26 May 2018 00:20:45 +0200 > > > > > > > > Janusz Krzysztofik wrote: > > > > > ... > > > > > Changes since v1: > > > > > - fix handling of devm_gpiod_get_optional() return values - thanks to > > > > > > > > > > Andy Shevchenko. > > > > > > > > Can you put the changelog after the "---" separator so that it does not > > > > appear in the final commit message? > > > > > > Yes, sure, sorry for that. > > > > > > > > +err_gpiod: > > > > > + if (err == -ENODEV || err == -ENOENT) > > > > > + err = -EPROBE_DEFER; > > > > > > > > Hm, isn't it better to make gpiod_find() return ERR_PTR(-EPROBE_DEFER) > > > > here [1]? At least, ENOENT should not be turned into EPROBE_DEFER, > > > > because it's returned when there's no entry matching the requested gpio > > > > in the lookup table, and deferring the probe won't solve this problem. > > > > > > ENOENT is also returned when no matching lookup table is found. That may > > > happen if consumer dev_name stored in the table differs from dev_name > > > assigned to the consumer by its bus, the platform bus in this case. For > > > that reason I think the consumer dev_name should be initialized in the > > > table after the device is registered, when its actual dev_name can be > > > obtained. If that device registration happens after the driver is already > > > registered, e.g., at late_initcall, the device is probed before its > > > lookup table is ready. For that reason returning EPROBE_DEFER seems > > > better to me even in the ENOENT case. > > Sorry, I don't get it. Aren't GPIO lookup tables supposed to be declared > > in board files, especially if the GPIO is used by a platform device? > > When would you have a lookup table registered later in the init/boot > > process? > > When e.g. I'd like to register my GPIO consumer platform device at > late_initcall for some reason, and I'm not sure what exact dev_name my > consomer will be registered with by the platform bus. You should know the name before the device is registered. > In that case I think I > should assign dev_name to the lookup table after the consumer device is > registered and its exact dev_name can be obtained, then register the table, I'm pretty sure it's not supposed to work like that. Resources attached to a device should be defined before the device is registered, not after, simply because when you call platform_device_register(), the device might be directly bind to the driver before the platform_device_register() calls return, and the driver will fail to probe the device if it doesn't find the GPIO it needs.