From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2A4242A8FE; Thu, 18 Jul 2024 15:13:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721315608; cv=none; b=cwzt7XzeqzSyTyFfhvxmFRIkpOs0cFfNmpeKNoQVCTbR7rVufbdak4gFbXadY7Q8t+68jGJa/euRZ/Nmtyze0KrR/VBuU46pi4QbQgSVvwVQIBShTOTTDWLazG4faYcWuB+jzyE38eoxhgA4sI5NGFB5zc0FkblK8k5b68w+D2A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721315608; c=relaxed/simple; bh=KGyvEQ54So9d/QSHQz8COPueg/2S62+77cBcHg1eiQk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=T9BxwU8JTOftJc/Qq485t7bFFb+uP1HNFiXazHqf6XdSfYp5NtJHWskZArOquepiCA3i04HxkO2T+h5d3MeXY/9+lzCRQilylQCVyjqthdAUWYn2fyan5SsTsLxOzNaPbvtYc6tvPtIluj3mBSoV/gSCdOMU+cqAuSrZ7D2aM3U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eFcriuRp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eFcriuRp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1FEFC116B1; Thu, 18 Jul 2024 15:13:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1721315607; bh=KGyvEQ54So9d/QSHQz8COPueg/2S62+77cBcHg1eiQk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=eFcriuRpt2IrddShWruMkpSuTxZRhE5FthCbkGHMdZMbV3E5kb/2ifSgVZk8XgpP6 DlrbqC+x3duLCM+iR0NQvXlC7TDwlBhSY4FgEnqQGS3+e8BvahzC0rlA66RKQUfLMY vikckXZTV48GNjJhCuKSkAhn6MKIk/XVaCdXLT54omcTX3TXJqT0bXOo9uiwM9BLQg sBQWeIGv6RwJMxaTaL5L76qicIzjYJNvnKA42kTp8sY/sr0jxqtRyS5XlDeEgNxsqV JWla6cRAkTka7yWlLY2DnoeQsTiW2ETeod84C086LfV4H2iwDP4R4KvfAcuboniE9o 4AY1/gxhBfRgg== Message-ID: Date: Thu, 18 Jul 2024 17:13:22 +0200 Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Question about gpio-hog To: Conor Dooley , Bough Chen Cc: Linus Walleij , Rob Herring , "linux-gpio@vger.kernel.org" , "'devicetree@vger.kernel.org'" , "imx@lists.linux.dev" , Aisheng Dong , Frank Li , Shenwei Wang References: <20240718-smudge-splashy-6e8addc80c02@spud> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 18/07/2024 16:47, Conor Dooley wrote: > On Thu, Jul 18, 2024 at 03:40:49AM +0000, Bough Chen wrote: >> Hi All, >> >> I have a question of ‘gpio-hog’, the property gpio-hog seems to be used in GPIO node rather than in users device node, so we can’t use the device-link feature. >> (sorry for resend, I use text/plain messages this time) >> >> e.g. >> >> pcal6524: gpio@22 { >>       … >> 　　　/* usdhc3 and QSPI share the same pin, here select SD3 pins */ >> 　　　usdhc3-qspi-sel-hog { >> 　　　　　　gpio-hog; >> 　　　　　　gpios = <16 GPIO_ACTIVE_HIGH>; >> 　　　　　　output-high; >> 　　　}; >> 　　　… >> }; >> >> &usdhc3 { >>      … >> } >> >> The board share the pins of usdhc3 and QSPI, a MUX use one GPIO pad from one I2C GPIO expander to control the selection. >> So before usdhc3 probe, need to make sure the gpio-hog is configed. Which means usdhc3 need to depend on usdhc3-qspi-sel-hog. >> >> To achieve that, I can add a fake GPIO properties like below: >> &usdhc3{ >>      … >>      hog-gpio = <&pcal6524 16 GPIO_ACTIVE_HIGH>; >> } >> >> Usdhc driver do not handle the hog-gpio, just use this fake hog-gpio to let the usdhc3 depends on pcal6524 IO expander. Make sure when usdhc driver probe, already select the usdhc3 pads on board. >> >> But this will trigger the DT check warning if related device binding has ““additionalProperties: false”  or  “unevaluatedProperties: false”. >> >> Can this be acceptable? Any thoughts for this case? I think this might be common user case for gpio-hog. > > I've got no idea what this device you're talking about is - but it seems > to me like the "hog-gpio" property is what you should be doing (although > probably called something like "enable-gpios" instead. > What you would do is send a patch for the dt-binding for this device, > adding a property, in which case the *Properties: false will stop > warning. If there is device dependency on the hog, I would say by definition of a hog that's not a hog. Hogs are for controller to initialize, but here your device driver needs it. This sounds like simple pin configuration for device. Best regards, Krzysztof