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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 E4280C43387 for ; Tue, 18 Dec 2018 10:40:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B9BE321841 for ; Tue, 18 Dec 2018 10:40:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726584AbeLRKkl (ORCPT ); Tue, 18 Dec 2018 05:40:41 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:50499 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726450AbeLRKkk (ORCPT ); Tue, 18 Dec 2018 05:40:40 -0500 Received: from kresse.hi.pengutronix.de ([2001:67c:670:100:1d::2a]) by metis.ext.pengutronix.de with esmtp (Exim 4.89) (envelope-from ) id 1gZCnj-0002cM-Do; Tue, 18 Dec 2018 11:40:35 +0100 Message-ID: <1545129634.5874.20.camel@pengutronix.de> Subject: Re: [PATCH] clk: imx: add CLK_GET_RATE_NOCACHE flag for i.MX8M composite clock From: Lucas Stach To: Fabio Estevam , Anson Huang Cc: "sboyd@kernel.org" , "s.hauer@pengutronix.de" , "linux-kernel@vger.kernel.org" , "linux-clk@vger.kernel.org" , dl-linux-imx , "kernel@pengutronix.de" , Fabio Estevam , "shawnguo@kernel.org" , "mturquette@baylibre.com" , "linux-arm-kernel@lists.infradead.org" Date: Tue, 18 Dec 2018 11:40:34 +0100 In-Reply-To: References: <1545101396-16335-1-git-send-email-Anson.Huang@nxp.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::2a 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-clk@vger.kernel.org Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org Am Dienstag, den 18.12.2018, 08:24 -0200 schrieb Fabio Estevam: > Hi Anson, > > On Tue, Dec 18, 2018 at 12:56 AM Anson Huang > wrote: > > > > On i.MX8M, some of the bus clocks' rate could be changed in TF-A, > > Do you mean ATF (ARM Trusted Firmware) instead? TF-A is the name of the day for what was formerly known as ATF... However I don't think that it's correct to just don't cache the clock settings. Normally the secure world firmware should not change any clock settings at runtime, or it would run into all kinds of conflicts with the clock driver. So there are probably some well known points in time like a suspend or resume event when the firmware might change clock settings, so we could instead use those to trigger an explicit invalidate of the clock caches with much lower overhead. Regards, Lucas