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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B62EC11D00 for ; Thu, 20 Feb 2020 07:46:50 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id E2912208C4 for ; Thu, 20 Feb 2020 07:46:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jZzP2NY2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E2912208C4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject: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=GIkOFYBPlZ6N245ThtOVLxfVaJYfj4L+sPPgc+m2TNU=; b=jZzP2NY2DoMJ2y +M6y2/t7dDjifuz5jRHHQBkMyPLbSdRYlvUjSsEt4efBGKreD9zPGRetiCPKfXOwcrlwK/ewpA1r3 tGaXolcIJOjfFPifcJ/OkPmDv+Ug4MjmjAgQyAuKXlVmQ+x7RNebi0oSKX7LWWTjWVkE3NFeWFe4X rx499Oq1MT4c7a6wku+EK7vLt4BFM5c1petLfG2YMAtR+fF/c2p80bkwWYwk8NgvWWdb47/OcH3Gd xxROjoNpF8b1QAF7ipE5HQ9T58a1nLhdM/TzQnsDisU14yN1qxPZ5N96nVOJ4GMKUkJK2Rh91e3NH 5M/cOJUelCjM0GSXxXHQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4gXX-0002EY-5h; Thu, 20 Feb 2020 07:46:31 +0000 Received: from bhuna.collabora.co.uk ([46.235.227.227]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4gXU-0002AR-Dk for linux-mtd@lists.infradead.org; Thu, 20 Feb 2020 07:46:30 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 6EF362927B3; Thu, 20 Feb 2020 07:46:26 +0000 (GMT) Date: Thu, 20 Feb 2020 08:46:23 +0100 From: Boris Brezillon To: Sergei Shtylyov Subject: Re: [PATCH RFT 0/2/2] mtd: hyperbus: add Renesas RPC-IF driver Message-ID: <20200220084623.3d5145fd@collabora.com> In-Reply-To: References: <16309076-4378-d9ff-30c3-93a46af1d803@ti.com> Organization: Collabora X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200219_234628_594488_E54DA287 X-CRM114-Status: GOOD ( 12.57 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Dirk Behme , Vignesh Raghavendra , Richard Weinberger , Mark Brown , linux-mtd@lists.infradead.org, Miquel Raynal Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Wed, 19 Feb 2020 23:13:36 +0300 Sergei Shtylyov wrote: > > One way would be to extend spi_mem_op to support above template along > > with a new field to distinguish SPI NOR vs HyperFlash protocol. HyperBus > > core can then register a spi_device and use spi-mem ops to talk to > > controller driver. > > We have discussed this idea with Mark Brown, the SPI maintainer, and > he wasn't terribly impressed (I've invited him to #mtd -- his nick is > broonie and mine is headless, I'm also adding him to CC:). > > > So, I suggest making Renesas RPC-IF backend a full fledged spi-mem > > driver (instead of driver/memory) and use extended spi_mem_op to support > > HyperFlash. > > I don't think cramming support for the different flash busses into > the SPI drivers is a good idea... That's what I thought at first (SPI and Hyperflash seemed different enough to not merge them), then I had a look at Vignesh's HyperFlash presentation [1], and there's one aspect that made me reconsider this PoV. Slide 25 (xSPI compliant HyperFlash): having devices bouncing from one driver to another depending on the mode they operate in is likely to be painful to handle. Not to mention that Octo+DTR is similar to HyperBus from an HW PoV (at the PHY level, they both have CS, CLK, DQS/RWDS, DQ/IO[0:7] signals, only the protocol differs). [1]https://elinux.org/images/3/38/HBMC-v1.pdf ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/