From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=2a00:1450:400c:c0c::22b; helo=mail-wr0-x22b.google.com; envelope-from=daniel.thompson@linaro.org; receiver=edk2-devel@lists.01.org Received: from mail-wr0-x22b.google.com (mail-wr0-x22b.google.com [IPv6:2a00:1450:400c:c0c::22b]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 09F4C220C1600 for ; Wed, 22 Nov 2017 12:07:21 -0800 (PST) Received: by mail-wr0-x22b.google.com with SMTP id k18so10701501wre.1 for ; Wed, 22 Nov 2017 12:11:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=2rTjdKS/u5fGxNhcctSLYeShVievsj9hiTI8LMuW+3c=; b=YF7HzcAn7eiaeaLxz3n4lUzAXq+xYsf/iF0whMqSrvSwL5sS93c482KXxAdLtYAVO0 bAJgLRhgZtXf4tl3lfJHUFucvn7LEPmZnfcTORGMIXW2g80/mc1AO50vY3bLA41yOo8n XK6i2YDnoafYvfZUK8+SM2Fh+d6N6jlgtXEKM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=2rTjdKS/u5fGxNhcctSLYeShVievsj9hiTI8LMuW+3c=; b=Qi60vZIVNRtN4y3aLuGgGIkM1lhcTgI0XTPyWhF8LGXvZvBdjkgSgSP5Vd48LAu7fe IuifFtWvAsNuTXioHJ3okQGcVkzbkFXrhQDXmaiOogJYFb1w0z1rXhghTnJmN/A9zDH/ GDYN9vit8g8BYg/qjYH2X60es8efRYW55THlfvafO1KzfvRqukaBv/oqhrQ2wWiNIMPw y1vPIDx2RYgg7uw3ioTP/VV+8EbHkl+qLcDUbicjUi2f11ZyGv24je4Swb0D9lCsN535 HMuh74hmmESFhDL33nB2NAJ709VE9b7g41k4LxL1qHaNhArxjbuWGcGELd/+TxeHzfuT ndjw== X-Gm-Message-State: AJaThX6XTlp+Kucr/5kxijUY8bGW6R2uRv8+BItlPZy4b5vzaf4NyAS8 7QnZDiCd0aRNBAea4UrLtZJg2Q== X-Google-Smtp-Source: AGs4zMaoS2kFJMEf7CSQ7t134sckERnQMf2yO71d+dg+l/1XbHfF+oKTpW3vZrYnuhF2jGfrhbhpRw== X-Received: by 10.223.195.113 with SMTP id e46mr10978404wrg.149.1511381497153; Wed, 22 Nov 2017 12:11:37 -0800 (PST) Received: from [192.168.1.142] (cpc87211-aztw31-2-0-cust196.18-1.cable.virginm.net. [82.46.60.197]) by smtp.googlemail.com with ESMTPSA id w46sm6328480wrb.86.2017.11.22.12.11.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Nov 2017 12:11:36 -0800 (PST) To: Ard Biesheuvel Cc: Udit Kumar , Leif Lindholm , "edk2-devel@lists.01.org" , Varun Sethi , Graeme Gregory References: From: Daniel Thompson Message-ID: <2166aaa7-2f96-50d4-4502-bbb9b8b9ef22@linaro.org> Date: Wed, 22 Nov 2017 20:11:34 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: Subject: Re: [RFC] ACPI table HID/CID allocation X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Nov 2017 20:07:22 -0000 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit On 22/11/17 19:39, Ard Biesheuvel wrote: > On 22 November 2017 at 11:30, Daniel Thompson > wrote: >> On 21/11/17 18:10, Udit Kumar wrote: >>> >>> Thanks Ard, >>> For internal SOC devices, this is perfectly ok to drop PRP0001 from CID. >>> >>>> This could be a valid reason to use PRP0001 + compatible, for things like >>>> I2C >>>> slaves that are external to the SoC >>> >>> >>> For external devices (for which HID is not available), you suggest to go >>> with PRP0001 + compatible or that device driver needs add ACPI HID >>> support. >> >> >> I don't think internal or external to the SoC would be any kind of deciding >> factor in how to best to bind, simply because I don't understand why there >> is no HID available. >> > > PRP0001 + compatible was invented to avoid the need to allocate a _HID > for each and every component in existence that can already be > identified by a DT compatible string (and little else except, e.g., a > I2C slave address) and is not deeply engrained in the SoC in terms of > clock tree, power states etc. So while internal/external may not be > the most accurate distinction, it is still a useful one IMHO. Hmnnn.... it sounds like jedec,spi-nor meets this test. There is only one property in the DT bindings that describes the device itself (fast read support) rather than its "bus address" (chip select, frequency). Further, that single property is obsolete, at least for Linux; the kernel driver now contains a quirks tables to look up by device ID whether fast read is supported and will use that on non-DT systems (and also to censor broken DT systems ;-) ). Daniel.