Received: by 2002:a25:e74b:0:0:0:0:0 with SMTP id e72csp2191128ybh; Fri, 24 Jul 2020 06:45:45 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz0XxYKiWKguDgdldueEKdhxZ1U1Mdf+XGO+7crUYJmFS+5111c0M1LmN2/YAMKGeGQ5LQt X-Received: by 2002:a17:906:da0f:: with SMTP id fi15mr8939517ejb.237.1595598345446; Fri, 24 Jul 2020 06:45:45 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1595598345; cv=none; d=google.com; s=arc-20160816; b=j09bJjZEmJSlunQO8LiALl7oAMUx+bSgT0MEWaH8TVGY9PK6YuugYHT4oIHgd9MPhv cU/RbqxG2PBgEEfN594cx8bHIjFzfEkIg7oSHbVnS06natJxOHtumK6qEcigCJu/5hyg kwIq5RfxNIYdhFk+M4afxcQ1BRDx9/EgnZyAL71a0Cq5NgyqEf5BaiTkkCBIdWwxpfW2 O88Opjfkw63K86SCr4U9uRviK/55G/G2gCSaRobfXO1gYNGIJlMr9HLP8l+hqdmLW8Hr 0qGt2tmd/v6joZaDOa379gX9YcUK0CW4oLz7UpV7HIiA+w/73Ex4smSBlYxJxbfupg8L jbpg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date; bh=JXeqjIaal3sbUrozH7WI79IYPdIu81pjoyVsh7NBxVk=; b=XEcoECD6tFpLxSNcuO0qw4hgfTPuSK3Enc8GyjKci/cfKFlN5jQ+iAIIvdYpAxhvQD EDEUwPfZ/HKOwbqjgCS+Hk76Q6hQZoOxiCUHSOLqBUV02OIsbKDt085RUeBrvnjmPyet SG32xIk7fXHRTmxSqfX+nLT2e/JDgssH7Azt9aA08y7i4rnCyGB8/xcxpMloTrYHN5o+ K+wOg9jmj1tmjozUUVhV3nWgVUzdhbKvM9JmN5SC7JaMtT3dmKtD15DEtSxAg13z2pqz oFK0oP700oxEFTutQaBEZI5NfdJsf+Frox/knoo4OPL0S03oXWCpiQYVU1LqQITn/mL6 7fSQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id q28si545973edw.196.2020.07.24.06.45.23; Fri, 24 Jul 2020 06:45:45 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726857AbgGXNol (ORCPT + 99 others); Fri, 24 Jul 2020 09:44:41 -0400 Received: from verein.lst.de ([213.95.11.211]:35740 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726326AbgGXNok (ORCPT ); Fri, 24 Jul 2020 09:44:40 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 9A94A68AFE; Fri, 24 Jul 2020 15:44:37 +0200 (CEST) Date: Fri, 24 Jul 2020 15:44:37 +0200 From: Christoph Hellwig To: Arnd Bergmann Cc: Ulf Hansson , linux-mmc , Christoph Hellwig , Rui Feng , linux-nvme@lists.infradead.org, linux-pci , "linux-kernel@vger.kernel.org" , Adrian Hunter , Greg Kroah-Hartman Subject: Re: [PATCH] mmc: core: Initial support for SD express card/host Message-ID: <20200724134437.GB3152@lst.de> References: <20200716141534.30241-1-ulf.hansson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 24, 2020 at 03:35:47PM +0200, Arnd Bergmann wrote: > Starting simple is generally a good idea, yes. > > It would be good to have feedback from the nvme driver maintainers. > > One way I can see the handshake working would be to have > an sdexpress class_driver that provides interfaces for both mmc > and nvme to link against. The mmc core can then create a > class device when it finds an sd-express device and that > class device contains a simple state machine that keeps track of > what either side think is going on, possibly also providing > a way to perform callbacks between the two sides. None of this is in scope for the NVMe spec, so I don't really want to deal with it in the NVMe driver in any way. Given that a SD express card just turns into a normal PCIe link if you really want to check that something probed I think you'd want to track if any PCIe driver is bound to the device. Or just wait and see if we really need anything after all.