From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 809D4C64ED8 for ; Mon, 27 Feb 2023 22:15:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=hvIyjRjS2IJvOyBXxbgG05ZtflFcaHUe8TP1rB3elpM=; b=i2bZKwj7hcJ3HB Y53Upfhba4qnjDkxmacDIJ2hd7LifhcK8o5C04mYJstrxpNYMDlSReBDCLE6YTRX4JuEgmprRv4gj eJ4hBh2l+OjaX8G65+zS9uMfn8CSGFG6s4z35ubu8wGdzd7p/8OJSFz0OffL3CVbYbqRHAUQl5eGF b2FMiAHtMDDsyKcV5h981LnvxjTCSTjjRsG77uV8fpwVLqayo1eWzGCxgknEDvUy6FzZ+t+UHHDuW iaiS8++h2NSNSJCQBBtWiuUYITRjZED5LCP1Q9tqD3jmo+AAThoKq5kCyMMbqLaysXUiR+KetYTIl HXhhKxGUKld15N8X6SOg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pWllS-00BPCR-L8; Mon, 27 Feb 2023 22:14:34 +0000 Received: from mail-oo1-f42.google.com ([209.85.161.42]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pWllQ-00BPBW-8k for linux-arm-kernel@lists.infradead.org; Mon, 27 Feb 2023 22:14:33 +0000 Received: by mail-oo1-f42.google.com with SMTP id p6-20020a4ab386000000b005252182b0e0so1243171ooo.6 for ; Mon, 27 Feb 2023 14:14:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=ZS2bF3+Kst9y6aMOuXBKptVY4beKNpQcXiRFClTf/bI=; b=VtFYEFGOpaBdjEOjlRtz45npS88eWAPOqUzx22MW7QMr5+2YzGaE89Xbb+F0OPiNW7 XAig5y+MmrR1StgY8JP5VZjJz9gNZBu2jGq4PDSe8Y5CIv7+ZMoPI/V2lr7iVzl6hs9a zoadJtl+444/UE4bw60fMjUX9lkW445FyASiGr07kZpmTu3bT1TpvYLBcgDkiX2M3tWk 7e1j+Yo1f3EvQzq6BDFH7vr20tV9BP0pwTp5yisDw5EY9/sIymNWUapWmcT6Mng3lFjj GqJyLvoFB5AsibW3xqZ+vrHsN2Uf9EoAMhNiosXparxvA19ZKNmeXffT+z8b4dMmvPl2 xWaw== X-Gm-Message-State: AO0yUKVffYOVuju3Aicg+yd4kZE2ksH0TCrAMiBneAVsPGiYyfTLLeCF zm4FbT4leV5RmGxwuwGWjg== X-Google-Smtp-Source: AK7set9a9wt8dYLW0+D9GTxaOE63A+at2SMod+AKLVoJqf5EzvyD9tdF199K0X72Q60jeiCDGB6/0A== X-Received: by 2002:a4a:6b12:0:b0:4f2:8f8:d2ff with SMTP id g18-20020a4a6b12000000b004f208f8d2ffmr70403ooc.6.1677536067377; Mon, 27 Feb 2023 14:14:27 -0800 (PST) Received: from robh_at_kernel.org (66-90-144-107.dyn.grandenetworks.net. [66.90.144.107]) by smtp.gmail.com with ESMTPSA id k22-20020a056820017600b00517a7ac36c8sm3124614ood.24.2023.02.27.14.14.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Feb 2023 14:14:27 -0800 (PST) Received: (nullmailer pid 1193336 invoked by uid 1000); Mon, 27 Feb 2023 22:14:26 -0000 Date: Mon, 27 Feb 2023 16:14:26 -0600 From: Rob Herring To: Sasha Finkelstein Cc: Hector Martin , Sven Peter , Alyssa Rosenzweig , Dmitry Torokhov , Krzysztof Kozlowski , - , Henrik Rydberg , linux-arm-kernel@lists.infradead.org, linux-input@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC 1/4] dt-bindings: input: touchscreen: Add Z2 controller bindings. Message-ID: <20230227221426.GA1048218-robh@kernel.org> References: <20230223-z2-for-ml-v1-0-028f2b85dc15@gmail.com> <20230223-z2-for-ml-v1-1-028f2b85dc15@gmail.com> <20230227195139.GA677578-robh@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230227_141432_332885_2456F18E X-CRM114-Status: GOOD ( 27.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Feb 27, 2023 at 09:06:28PM +0100, Sasha Finkelstein wrote: > On Mon, 27 Feb 2023 at 20:51, Rob Herring wrote: > > > > > +properties: > > > + compatible: > > > + const: apple,z2-touchscreen > > > > Is 'z2' anything other than a touchscreen? If not, '-touchscreen' is > > redundant. If so, then what else is there? You should be describing > > physical devices, not just a protocol for touchscreen. > > > > This is a class of touchscreen controllers that talk the z2 protocol > over spi. Yes, you already said that much. So nothing else for this piece of h/w? Then 'apple,z2' is sufficient. Well maybe. You are assuming all h/w in the world speaking 'z2' is the same (to software). Usually that's not a safe assumption, but maybe Apple is better at not changing the h/w... Normally, the 'protocol' to talk to a device is only part of it. There's other pieces like how to turn the device on and off which need h/w specific knowledge. If you need any of that, then you need specific compatibles. Adding properties for each variation doesn't end up well. > > > > + touchscreen-size-y = <640>; > > > + apple,z2-device-name = "MacBookPro17,1 Touch Bar"; > > > > Why do we need this string? If you want a human consumed label for > > some identification, we have a property for that purpose. It's called > > 'label'. But when there is only 1 instance, I don't really see the > > point. > > I want a libinput-consumed label to distinguish between devices > using this protocol. I know little about libinput, but how would it know about 'apple,z2-device-name'? > It is used both for 'normal' touchscreens, and, > as is in this example a 'touchbar', which absolutely should not be > treated as a normal touchscreen, and needs special handling in > userspace. Meaning there are both touchscreens and touchbars using this? That sounds like s/w needs this information. From a DT perspective, 'compatible' is how DT defines exactly what the h/w is and how to use it. That also doesn't sound like a unique issue. Doesn't the kernel provide a standard way to tell userspace what's a touchscreen vs. touchpad vs. ??? Rob _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel