From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D0918342C93; Tue, 3 Mar 2026 13:08:53 +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=1772543335; cv=none; b=i6yO2IumE2I1wFQ829Op+ZPs/EB+GiDjeoE5Pgjd4uKvuV9BhDed06t+4iUSB4KusMrONrCFV75Ffqex1GYTg+xy1wdrf5tl9Ryc2kGtPJDozzFJukyIo0shzU5YyZ7RPw5mkUXa5QFiXVpGhagOtctwnohloXxkFjKUapEgXSM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772543335; c=relaxed/simple; bh=+aD7rHRYNhH4mWSwuRacRuHrsbhzN5dK0LutoaXKLPY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=smYZOFZcTcYdg9MCv1HH3nQ/c895+Fyj9U96FHNV0ZsB+2f8cnHhp6uDqj7ZtxGkdicvYZvyNPPQlvyx4HQEktKmP0sxIXlBmkw8m1ImdqUL4hqiVK7sM/7rjWUkdEVNn9fN93zoSVGTWkjXOmVs4HKLtCdoVXlFz4DQga5KQwc= 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 02975497; Tue, 3 Mar 2026 05:08:47 -0800 (PST) Received: from pluto (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BA2673F73B; Tue, 3 Mar 2026 05:08:49 -0800 (PST) Date: Tue, 3 Mar 2026 13:08:46 +0000 From: Cristian Marussi To: Geert Uytterhoeven Cc: Cristian Marussi , 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, 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, kuninori.morimoto.gx@renesas.com, marek.vasut+renesas@gmail.com Subject: Re: [PATCH 00/11] SCMI Clock rates discovery rework Message-ID: References: <20260227153225.2778358-1-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-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Mar 02, 2026 at 02:25:00PM +0100, Geert Uytterhoeven wrote: > Hi Cristian, > > Thanks for your series! > > On Fri, 27 Feb 2026 at 16:33, Cristian Marussi wrote: > > it was a known limitation, in the SCMI Clock protocol support, the lack of > > dynamic allocation around per-clock rates discovery: fixed size statically > > per-clock rates arrays did not scale and was increasingly a waste of memory > > (see [1]). > > > > This series aim at solving this in successive steps: > > > > - simplify and reduce to the minimum possible the rates data info exposed > > to the SCMI driver by scmi_clock_info > > - move away from static fixed allocation of per-clock rates arrays in > > favour of a completely dynamic runtime allocation: just allocate what > > is needed based on the effectively discovered > > > > This is done in patches 1-6. > > > > A further bigger optimization suggested in a past series [1] by Etienne > > s/[1]/[2]/ > > > would be, whenever allowed by the spec, to limit upfront the number of > > queries in order to simply retrieve min and max rate, that are indeed the > > only rates needed by the CLK SCMI driver. > > > > The approach proposed in [1] was open coding and duplicating some of the > > What does [1] refer to? I messed up the refs..of course...it was just a reference to your thread where the number of rates where staticallty raised to 64. > > > functionalities already provided by SCMI iterators, though. > > > > Patch 7-10 implement such optimization instead by: > > > > - reworking core SCMI iterators to support bound enumerations > > - use such new bound iterators to perform the minimum number of queries > > in order to ony retrieve min an max rate > > > > As a final result now the rates enumeration triggered by the CLK SCMI > > driver, while still allocating for all the existent rates, miminize the > > number of SCMI CLK_DESCRIBE_RATE messages needed to obtain min and max. > > > > Finally, patch 11 introduces a new clock protocol operation to be able to > > trigger anytime on demand a full enumeration and obtain the full list of > > rates when needed, not only min/max: this latter method is really only used > > currently by some dowstream SCMI Test driver of mine. > > > > Based on v7.0-rc1. > > > > Tested on JUNO and an emulated environment. > > Thank you, this removes the need for increasing SCMI_MAX_NUM_RATES on > R-Car X5H, while decreasing memory usage. > Tested-by: Geert Uytterhoeven > Thanks for testing in the real world ! Cristian