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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08713CD6910 for ; Tue, 10 Oct 2023 09:23:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230176AbjJJJXc (ORCPT ); Tue, 10 Oct 2023 05:23:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230372AbjJJJXQ (ORCPT ); Tue, 10 Oct 2023 05:23:16 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3E5D61998; Tue, 10 Oct 2023 02:22:07 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id ACC341FB; Tue, 10 Oct 2023 02:22:47 -0700 (PDT) Received: from pluto (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D95103F762; Tue, 10 Oct 2023 02:22:05 -0700 (PDT) Date: Tue, 10 Oct 2023 10:22:03 +0100 From: Cristian Marussi To: Sudeep Holla Cc: "Peng Fan (OSS)" , linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, ranjani.vaidyanathan@nxp.com, glen.wienecke@nxp.com, Peng Fan Subject: Re: [RFC] firmware: arm_scmi: clock: add fixed clock attribute support Message-ID: References: <20231010022911.4106863-1-peng.fan@oss.nxp.com> <20231010091223.rvcyrgbjcrmjzmvp@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231010091223.rvcyrgbjcrmjzmvp@bogus> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 10, 2023 at 10:12:23AM +0100, Sudeep Holla wrote: > On Tue, Oct 10, 2023 at 10:29:11AM +0800, Peng Fan (OSS) wrote: > > From: Peng Fan > > > > There are clocks: > > system critical, not allow linux to disable, change rate > > allow linux to get rate, because some periphals will use the frequency > > to configure periphals. > > > > So introduce an attribute to indicated FIXED clock > > > > Signed-off-by: Peng Fan > > --- > > drivers/clk/clk-scmi.c | 6 ++++++ > > drivers/firmware/arm_scmi/clock.c | 5 ++++- > > include/linux/scmi_protocol.h | 1 + > > 3 files changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c > > index 8cbe24789c24..a539a35bd45a 100644 > > --- a/drivers/clk/clk-scmi.c > > +++ b/drivers/clk/clk-scmi.c > > @@ -182,6 +182,10 @@ static const struct clk_ops scmi_clk_ops = { > > .determine_rate = scmi_clk_determine_rate, > > }; > > > > +static const struct clk_ops scmi_fixed_rate_clk_ops = { > > + .recalc_rate = scmi_clk_recalc_rate, > > +}; > > + > > static const struct clk_ops scmi_atomic_clk_ops = { > > .recalc_rate = scmi_clk_recalc_rate, > > .round_rate = scmi_clk_round_rate, > > @@ -293,6 +297,8 @@ static int scmi_clocks_probe(struct scmi_device *sdev) > > if (is_atomic && > > sclk->info->enable_latency <= atomic_threshold) > > scmi_ops = &scmi_atomic_clk_ops; > > + else if (sclk->info->rate_fixed) > > + scmi_ops = &scmi_fixed_rate_clk_ops; > > else > > scmi_ops = &scmi_clk_ops; > > > > diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c > > index ddaef34cd88b..8c52db539e54 100644 > > --- a/drivers/firmware/arm_scmi/clock.c > > +++ b/drivers/firmware/arm_scmi/clock.c > > @@ -46,6 +46,7 @@ struct scmi_msg_resp_clock_attributes { > > #define SUPPORTS_RATE_CHANGE_REQUESTED_NOTIF(x) ((x) & BIT(30)) > > #define SUPPORTS_EXTENDED_NAMES(x) ((x) & BIT(29)) > > #define SUPPORTS_PARENT_CLOCK(x) ((x) & BIT(28)) > > +#define SUPPORTS_FIXED_RATE_CLOCK(x) ((x) & BIT(27)) > > I don't see this in the specification, am I missing something ? > > And why do we need it. Can't this be discrete clock with only one clock > rate ? Or step clock with both lowest and highest the same and step being 0. > At-least I don't see the need to change the spec for this and hence no need > to assign any attribute bit-field to represent the same. > No this is not in the spec, it would require a spec change. My understanding is that they have clocks that CAN have more than one rate BUT such clock cannot be changed by Linux, only other agents can enable/disable/set_rate BUT they still want to be able to query the current rate for configuration purposes. Thanks, Cristian