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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 08AEDC433ED for ; Fri, 30 Apr 2021 08:47:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C38906141C for ; Fri, 30 Apr 2021 08:47:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231129AbhD3IsL (ORCPT ); Fri, 30 Apr 2021 04:48:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229529AbhD3IsJ (ORCPT ); Fri, 30 Apr 2021 04:48:09 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF45EC06174A for ; Fri, 30 Apr 2021 01:47:21 -0700 (PDT) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=[IPv6:::1]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lcOnm-0002EN-QZ; Fri, 30 Apr 2021 10:47:10 +0200 Message-ID: <914b4e28b1313fc3b0293faa60a21cb6afb83e40.camel@pengutronix.de> Subject: Re: [PATCH 16/16] soc: imx: gpcv2: remove waiting handshake in power up From: Lucas Stach To: "Peng Fan (OSS)" , robh+dt@kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de Cc: kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, p.zabel@pengutronix.de, krzk@kernel.org, agx@sigxcpu.org, marex@denx.de, andrew.smirnov@gmail.com, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, ping.bai@nxp.com, frieder.schrempf@kontron.de, aford173@gmail.com, abel.vesa@nxp.com, Peng Fan Date: Fri, 30 Apr 2021 10:47:08 +0200 In-Reply-To: References: <20210429073050.21039-1-peng.fan@oss.nxp.com> <20210429073050.21039-17-peng.fan@oss.nxp.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.4 (3.38.4-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Freitag, dem 30.04.2021 um 15:14 +0800 schrieb Peng Fan (OSS): > > On 2021/4/29 22:34, Lucas Stach wrote: > > Am Donnerstag, dem 29.04.2021 um 15:30 +0800 schrieb Peng Fan (OSS): > > > From: Peng Fan > > > > > > i.MX8MM has blk ctl module, the handshake can only finish after setting > > > blk ctl. The blk ctl driver will set the bus clk bit and the handshake > > > will finish there. we just add a delay and suppose the handshake will > > > finish after that. > > > > Instead of this patch, just drop patch 05/16 from this series. I think > > we should leave a comment in the code on why we aren't waiting for the > > handshake ack, as this is non-obvious from looking at the driver code. > > > > Basically add a polished version of the commit log from this patch into > > the driver code. > > After thinking more, for power down, we need wait handshake. For power > up, we could ignore handshake, because BLK-CTL setting bus clk en > will auto trigger handshake. > > For power down, the bus clk en already set, and we need wait, otherwise > we need add delay there. > > So I would only drop the power up waiting and add some comments there. Ah, right. This way makes a lot of sense. Regards, Lucas