From nobody Wed Apr 8 04:41:11 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4476D3DD531; Tue, 10 Mar 2026 18:41:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773168095; cv=none; b=VKeZPeP/2wnePeb3htebL3HVdApgOgYzbSUNNEeQRvIxhlGVP1yO1v/dzP84SaQBCeHHL9KqpC4ambvK9W7mEFvP3aHp+ifIfvikFQ9reVPoxGNqIRADTETEeyEOXSWaGuK1Qe65uvP12b6ke+Fhrd6PZWyQiDPSATcoASq+jHg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773168095; c=relaxed/simple; bh=Fe70dvm/fvloZZ/pzMVRZXpVJRbHMWgs0CJxlTumHmY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QtH8h1yqoHiZehsk2cfZChl/dCUbAH3kfy0uqbBycgrdW+qpn2+Daed5Vcw86IOvz90R7T3hDhiACRE3cYFxDKLpdrlsJp059XaM7iA4grvQLCRUfA+NCQ6mz7OqAebGnygNPkuRoRhDMog+8S2nGg0ooFbRWkMCJ2SM4ePIq64= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 4B4D41BA8; Tue, 10 Mar 2026 11:41:23 -0700 (PDT) Received: from pluto.guest.local (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 244953F7BD; Tue, 10 Mar 2026 11:41:25 -0700 (PDT) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, arm-scmi@vger.kernel.org, linux-clk@vger.kernel.org, linux-renesas-soc@vger.kernel.org Cc: sudeep.holla@arm.com, philip.radford@arm.com, james.quinlan@broadcom.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, etienne.carriere@foss.st.com, peng.fan@oss.nxp.com, michal.simek@amd.com, dan.carpenter@linaro.org, geert+renesas@glider.be, kuninori.morimoto.gx@renesas.com, marek.vasut+renesas@gmail.com, Cristian Marussi Subject: [PATCH v2 12/13] firmware: arm_scmi: Use bound iterators to minimize discovered rates Date: Tue, 10 Mar 2026 18:40:29 +0000 Message-ID: <20260310184030.3669330-13-cristian.marussi@arm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260310184030.3669330-1-cristian.marussi@arm.com> References: <20260310184030.3669330-1-cristian.marussi@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Clock rates are guaranteed to be returned in ascending order for SCMI clock protocol versions greater than 1.0: in such a case, use bounded iterators to minimize the number of message exchanges needed to discover min and max rate. Signed-off-by: Cristian Marussi --- v1 --> v2 - fixed final ret value in scmi_clock_describe_get --- drivers/firmware/arm_scmi/clock.c | 90 +++++++++++++++++++++++++++---- 1 file changed, 81 insertions(+), 9 deletions(-) diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/= clock.c index a7dbb0c4f31c..f50689bf5414 100644 --- a/drivers/firmware/arm_scmi/clock.c +++ b/drivers/firmware/arm_scmi/clock.c @@ -160,6 +160,7 @@ struct scmi_clock_rate_notify_payld { struct scmi_clock_desc { u32 id; bool rate_discrete; + unsigned int tot_rates; unsigned int num_rates; u64 *rates; #define RATE_MIN 0 @@ -489,15 +490,16 @@ iter_clk_describe_update_state(struct scmi_iterator_s= tate *st, } =20 if (!st->max_resources) { - int num_rates =3D st->num_returned + st->num_remaining; + unsigned int tot_rates =3D st->num_returned + st->num_remaining; =20 - p->clkd->rates =3D devm_kcalloc(p->dev, num_rates, + p->clkd->rates =3D devm_kcalloc(p->dev, tot_rates, sizeof(*p->clkd->rates), GFP_KERNEL); if (!p->clkd->rates) return -ENOMEM; =20 /* max_resources is used by the iterators to control bounds */ - st->max_resources =3D st->num_returned + st->num_remaining; + p->clkd->tot_rates =3D tot_rates; + st->max_resources =3D tot_rates; } =20 return 0; @@ -520,8 +522,8 @@ iter_clk_describe_process_response(const struct scmi_pr= otocol_handle *ph, } =20 static int -scmi_clock_describe_rates_get(const struct scmi_protocol_handle *ph, u32 c= lk_id, - struct clock_info *cinfo) +scmi_clock_describe_rates_get_full(const struct scmi_protocol_handle *ph, + struct scmi_clock_desc *clkd) { int ret; void *iter; @@ -530,7 +532,6 @@ scmi_clock_describe_rates_get(const struct scmi_protoco= l_handle *ph, u32 clk_id, .update_state =3D iter_clk_describe_update_state, .process_response =3D iter_clk_describe_process_response, }; - struct scmi_clock_desc *clkd =3D &cinfo->clkds[clk_id]; struct scmi_clk_ipriv cpriv =3D { .clkd =3D clkd, .dev =3D ph->dev, @@ -550,17 +551,88 @@ scmi_clock_describe_rates_get(const struct scmi_proto= col_handle *ph, u32 clk_id, if (!clkd->num_rates) return 0; =20 + if (clkd->rate_discrete) + sort(clkd->rates, clkd->num_rates, + sizeof(clkd->rates[0]), rate_cmp_func, NULL); + + return 0; +} + +static int +scmi_clock_describe_rates_get_lazy(const struct scmi_protocol_handle *ph, + struct scmi_clock_desc *clkd) +{ + struct scmi_iterator_ops ops =3D { + .prepare_message =3D iter_clk_describe_prepare_message, + .update_state =3D iter_clk_describe_update_state, + .process_response =3D iter_clk_describe_process_response, + }; + struct scmi_clk_ipriv cpriv =3D { + .clkd =3D clkd, + .dev =3D ph->dev, + }; + unsigned int first, last; + void *iter; + int ret; + + iter =3D ph->hops->iter_response_init(ph, &ops, 0, CLOCK_DESCRIBE_RATES, + sizeof(struct scmi_msg_clock_describe_rates), + &cpriv); + if (IS_ERR(iter)) + return PTR_ERR(iter); + + /* Try to grab a triplet, so that in case is NON-discrete we are done */ + first =3D 0; + last =3D 2; + ret =3D ph->hops->iter_response_run_bound(iter, &first, &last); + if (ret) + goto out; + + /* If discrete grab the last value, which should be the max */ + if (clkd->rate_discrete && clkd->tot_rates > 3) { + first =3D clkd->tot_rates - 1; + last =3D clkd->tot_rates - 1; + ret =3D ph->hops->iter_response_run_bound(iter, &first, &last); + } + +out: + ph->hops->iter_response_cleanup(iter); + + return ret; +} + +static int +scmi_clock_describe_rates_get(const struct scmi_protocol_handle *ph, + u32 clk_id, struct clock_info *cinfo) +{ + struct scmi_clock_desc *clkd =3D &cinfo->clkds[clk_id]; + int ret; + + /* + * Since only after SCMI Clock v1.0 the returned rates are guaranteed to + * be discovered in ascending order, lazy enumeration cannot be use for + * SCMI Clock v1.0 protocol. + */ + if (PROTOCOL_REV_MAJOR(ph->version) > 0x1) + ret =3D scmi_clock_describe_rates_get_lazy(ph, clkd); + else + ret =3D scmi_clock_describe_rates_get_full(ph, clkd); + + if (ret) + return ret; + + clkd->info.min_rate =3D clkd->rates[RATE_MIN]; if (!clkd->rate_discrete) { clkd->info.max_rate =3D clkd->rates[RATE_MAX]; dev_dbg(ph->dev, "Min %llu Max %llu Step %llu Hz\n", clkd->rates[RATE_MIN], clkd->rates[RATE_MAX], clkd->rates[RATE_STEP]); } else { - sort(clkd->rates, clkd->num_rates, - sizeof(clkd->rates[0]), rate_cmp_func, NULL); clkd->info.max_rate =3D clkd->rates[clkd->num_rates - 1]; + dev_dbg(ph->dev, "Clock:%s DISCRETE:%d -> Min %llu Max %llu\n", + clkd->info.name, clkd->rate_discrete, + clkd->info.min_rate, clkd->info.max_rate); } - clkd->info.min_rate =3D clkd->rates[RATE_MIN]; =20 return 0; } --=20 2.53.0