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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D5CBC433EF for ; Fri, 1 Oct 2021 06:23:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53CD361A57 for ; Fri, 1 Oct 2021 06:23:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352137AbhJAGZH (ORCPT ); Fri, 1 Oct 2021 02:25:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:53130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230478AbhJAGZD (ORCPT ); Fri, 1 Oct 2021 02:25:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3C61061A57; Fri, 1 Oct 2021 06:23:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633069400; bh=vWqqxr539aef2V+4cScV97lUuywByujLgziy43fXUnw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qMcp2Tf4CCPiR0iR8tQvpVTgTKJ0K6YMxk/WLiah32A5njx5E2jeiNE7a+Km4sxY7 BgNvTBSavBv1ys/RKaTC4hHv+zmf42aPhaQOmjgBa1m0k9KHQF7OVojqBsVj7iKTXT /pWwzTKyWF/IyS6X2lM95AUeWkvL6ZVQsYrTLs5SHVYqnWC1Sq3EzfdrspRD8Fe9Um dBq8KRyQElBVD4h1Vt+CQ+5JbV/8JQ94tFF5PVzFxRBG+d1FeIK2C8DdPOFiHnz6Qy CVrLrzKlO/Jce7yVdvTVryFM6NRX/02oLe2RuNEA+6RdXv7FKYXBbT73bkD7MXLRka aNDMXUrHift5Q== Date: Fri, 1 Oct 2021 11:53:16 +0530 From: Vinod Koul To: Pratyush Yadav Cc: Paul Kocialkowski , Vignesh Raghavendra , Tomi Valkeinen , Laurent Pinchart , Nikhil Devshatwar , Chunfeng Yun , Kishon Vijay Abraham I , Rob Herring , linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org Subject: Re: [PATCH v5 2/6] phy: cdns-dphy: Add Rx support Message-ID: References: <20210902185543.18875-1-p.yadav@ti.com> <20210902185543.18875-3-p.yadav@ti.com> <20210917172809.rjtf7ww7vjcfvey5@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210917172809.rjtf7ww7vjcfvey5@ti.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pratyush, On 17-09-21, 22:58, Pratyush Yadav wrote: > +Rob > > On 16/09/21 12:22PM, Paul Kocialkowski wrote: > > Hi, > > > > On Fri 03 Sep 21, 00:25, Pratyush Yadav wrote: > > > The Cadence DPHY can be used to receive image data over the CSI-2 > > > protocol. Add support for Rx mode. The programming sequence differs from > > > the Tx mode so it is added as a separate set of hooks to isolate the two > > > paths. The mode in which the DPHY has to be used is selected based on > > > the compatible. > > > > I just realized that I didn't follow-up on a previous revision on the debate > > about using the phy sub-mode to distinguish between rx/tx. > > > > I see that you've been using a dedicated compatible, but I'm not sure this is a > > good fit either. My understanding is that the compatible should describe a group > > of register-compatible revisions of a hardware component, not how the hardware > > is used specifically. I guess the distinction between rx/tx falls under > > the latter rather than the former. > > I am not sure if that is the case. For example, we use "ti,am654-ospi" > for Cadence Quadspi controller. The default compatible, "cdns,qspi-nor", > only supports Quad SPI (4 lines). The "ti,am654-ospi" compatible also > supports Octal SPI (8 lines). Those are hardware defaults right? > In addition, I feel like the Rx DPHY is almost a different type of > device from a Tx DPHY. The programming sequence is completely different, Is that due to direction or something else..? > the clocks required are different, etc. So I think using a different > compatible for Rx mode makes sense. Is the underlaying IP not capable of both TX and RX and in the specific situations you are using it as TX and RX. I am okay that default being TX but you can use Paul's approach of direction with this to make it better proposal -- ~Vinod 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04C2CC433F5 for ; Fri, 1 Oct 2021 06:23:24 +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 AA65E61A58 for ; Fri, 1 Oct 2021 06:23:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AA65E61A58 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org 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=4qh8jGZLwFop1cjQY69L6bGSxlgRLKuNL5peB+9dBsg=; b=VUAbmTOmAa/7Kt o9zCFv1OOc8U6vQUAGoIKJLPIqUgw66bKoM6+j8wxVg7zKxL258tRogrRQgR/KGjPs3YlUp46s7AT aI/t7F66mc0ocw9vZqmqAPvKfoLC1MZ8XSTkXq02qE7geKBcY80lyPpl8E6MdIoLzCE1VtuuBKPFz GbBU8JqQVPFAfs3FRG37bTr5qmb6eLrU0aIQrECOS7UpD3QxgHFxWQ36+S0ouU5oZPmU4Y/iJ38Ng 7Wna5n+9Kux7ADtkEy5W+hJ8w+sLf0S9A/lLSnwbI8PwW8ryuh7+CHAiHJPoJ88vrQvp6thuMAOhO YjcxYsdinwOg5cxhDg8A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mWBx5-00Gn6h-7v; Fri, 01 Oct 2021 06:23:23 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mWBx2-00Gn5q-HV for linux-phy@lists.infradead.org; Fri, 01 Oct 2021 06:23:21 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3C61061A57; Fri, 1 Oct 2021 06:23:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633069400; bh=vWqqxr539aef2V+4cScV97lUuywByujLgziy43fXUnw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qMcp2Tf4CCPiR0iR8tQvpVTgTKJ0K6YMxk/WLiah32A5njx5E2jeiNE7a+Km4sxY7 BgNvTBSavBv1ys/RKaTC4hHv+zmf42aPhaQOmjgBa1m0k9KHQF7OVojqBsVj7iKTXT /pWwzTKyWF/IyS6X2lM95AUeWkvL6ZVQsYrTLs5SHVYqnWC1Sq3EzfdrspRD8Fe9Um dBq8KRyQElBVD4h1Vt+CQ+5JbV/8JQ94tFF5PVzFxRBG+d1FeIK2C8DdPOFiHnz6Qy CVrLrzKlO/Jce7yVdvTVryFM6NRX/02oLe2RuNEA+6RdXv7FKYXBbT73bkD7MXLRka aNDMXUrHift5Q== Date: Fri, 1 Oct 2021 11:53:16 +0530 From: Vinod Koul To: Pratyush Yadav Cc: Paul Kocialkowski , Vignesh Raghavendra , Tomi Valkeinen , Laurent Pinchart , Nikhil Devshatwar , Chunfeng Yun , Kishon Vijay Abraham I , Rob Herring , linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org Subject: Re: [PATCH v5 2/6] phy: cdns-dphy: Add Rx support Message-ID: References: <20210902185543.18875-1-p.yadav@ti.com> <20210902185543.18875-3-p.yadav@ti.com> <20210917172809.rjtf7ww7vjcfvey5@ti.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210917172809.rjtf7ww7vjcfvey5@ti.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210930_232320_620410_51DD3B40 X-CRM114-Status: GOOD ( 21.84 ) X-BeenThere: linux-phy@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux Phy Mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org Hi Pratyush, On 17-09-21, 22:58, Pratyush Yadav wrote: > +Rob > > On 16/09/21 12:22PM, Paul Kocialkowski wrote: > > Hi, > > > > On Fri 03 Sep 21, 00:25, Pratyush Yadav wrote: > > > The Cadence DPHY can be used to receive image data over the CSI-2 > > > protocol. Add support for Rx mode. The programming sequence differs from > > > the Tx mode so it is added as a separate set of hooks to isolate the two > > > paths. The mode in which the DPHY has to be used is selected based on > > > the compatible. > > > > I just realized that I didn't follow-up on a previous revision on the debate > > about using the phy sub-mode to distinguish between rx/tx. > > > > I see that you've been using a dedicated compatible, but I'm not sure this is a > > good fit either. My understanding is that the compatible should describe a group > > of register-compatible revisions of a hardware component, not how the hardware > > is used specifically. I guess the distinction between rx/tx falls under > > the latter rather than the former. > > I am not sure if that is the case. For example, we use "ti,am654-ospi" > for Cadence Quadspi controller. The default compatible, "cdns,qspi-nor", > only supports Quad SPI (4 lines). The "ti,am654-ospi" compatible also > supports Octal SPI (8 lines). Those are hardware defaults right? > In addition, I feel like the Rx DPHY is almost a different type of > device from a Tx DPHY. The programming sequence is completely different, Is that due to direction or something else..? > the clocks required are different, etc. So I think using a different > compatible for Rx mode makes sense. Is the underlaying IP not capable of both TX and RX and in the specific situations you are using it as TX and RX. I am okay that default being TX but you can use Paul's approach of direction with this to make it better proposal -- ~Vinod -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy