From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3022A44E044 for ; Fri, 5 Jun 2026 07:26:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780644386; cv=none; b=FHEIRWW/8FoEDgfUqbb53f14W9iw+XuQwE91msUItSYX1EEII7cinxsENsOy0pSm7jCAHAMlXKuW+J4N/jbS/Kf43xYZnxHcu1SZGuD//AZ6GCGJehoy+SGJ99STjD9uUz/8rb0Jl/zYlUVV2NA78+PDzRbhksq96PZn78OyzR0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780644386; c=relaxed/simple; bh=Blfq6eemSgWS0AMSuwnG+29kqyOXvU+JSSagUSUo0YA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=Gwshvkqo2Zh515K6fOrDAKMMSTGOd4TXGHYhoTK5yFQVr/O/XnGtKuz9Xu9/Z0WZ5UcLsW7k3VVzg9kEntKUq3VJNLQlct4PgPYXSLE3mx+goXjrfKYCZAmCu8Y7+piFQoPD5rHxFunHsBgB26uDe3xHzosys7YqVmARZgK701M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=1HExFZQ7; arc=none smtp.client-ip=185.246.85.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="1HExFZQ7" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 8FA7A4E40781; Fri, 5 Jun 2026 07:26:22 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 575225FED1; Fri, 5 Jun 2026 07:26:22 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 9A214106A1E65; Fri, 5 Jun 2026 09:26:16 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1780644381; h=from:subject:date:message-id:to:cc:mime-version:content-type: in-reply-to:references; bh=dJs1UXUNkLhBR/S0VALc0PkMzbs22zwOjldoT+MQiOE=; b=1HExFZQ71mYhu9loC8vT9RuOdU20EdrN8UjyVoOTSvyDNV0zdifjoy/HtaTQyrefq/5Arf 34MwRdSYY4s2W9yEviPjziQyYRjT3DqYpyQgoNPSF28Hd7EXzr17OCWdNlXWXqdrwpy8Kp XJv40cpGmgtEmbfe3xkZPsklXTAZHo6BmR/sJHisgg/WaL8IjT2v5i0eJA2jpLHE9xAmHq JujoPbzRynWgqH61lZ7FStVew0vxVV7a4om6JdkI+DLjMOfAR6aHFSNeJ/J2sFuKllFsyW b/JYDCDCCP2vpn9BBQnu3thwMxcC0PwCniHNtSu2YPt5Cl92fEbWvkw+iDPf4A== From: Miquel Raynal To: Conor Dooley Cc: Conor Dooley , Santhosh Kumar K , , , , , , , , , , , , , , , , Subject: Re: [PATCH v3 01/13] spi: dt-bindings: allow spi-max-frequency to specify a frequency pair In-Reply-To: <20260605-regulate-crawling-253c6d6bd971@wendy> (Conor Dooley's message of "Fri, 5 Jun 2026 08:17:18 +0100") References: <87cxy92llq.fsf@bootlin.com> <20260602-aptly-bunkbed-1bd3a8d63d54@spud> <875x3zzkji.fsf@bootlin.com> <20260603-neatly-twine-e89b923f5cb6@spud> <87o6hry4d4.fsf@bootlin.com> <20260603-balance-encounter-94f69e1577f3@spud> <87ik7yydyv.fsf@bootlin.com> <20260604-shrunk-acclaim-25368d7ad63e@spud> <87a4t9wl7r.fsf@bootlin.com> <20260605-regulate-crawling-253c6d6bd971@wendy> User-Agent: mu4e 1.12.7; emacs 30.2 Date: Fri, 05 Jun 2026 09:26:13 +0200 Message-ID: <87tsrh4fe2.fsf@bootlin.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Last-TLS-Session-Version: TLSv1.3 On 05/06/2026 at 08:17:18 +01, Conor Dooley wrote: > On Fri, Jun 05, 2026 at 08:32:56AM +0200, Miquel Raynal wrote: >> On 04/06/2026 at 09:36:49 +01, Conor Dooley wrote: >> >> > On Thu, Jun 04, 2026 at 09:14:16AM +0200, Miquel Raynal wrote: >> >> Hi Conor, >> >> >> >> >> >> > Right, and this I guess is what scuppers letting the controller driver >> >> >> >> > sort the configuration out itself and leaving the property as-is. >> >> >> >> > It could be that the speed in spi-max-frequency is lower than the "base >> >> >> >> > speed" of the controller but because of board routing or device >> >> >> >> > capability that the tuned mode is still required, right? >> >> >> >> >> >> >> >> I do not actually expect any tuned mode/frequency to be mandatory. >> >> >> > >> >> >> > I think you misunderstood my use of "required", I meant that the new >> >> >> > property/information was needed in the scenario I described, not that it >> >> >> > should be a required property in a binding. >> >> >> >> >> >> Yes I misunderstood the term indeed. However I still fail to catch what >> >> >> you meant here, I'm sorry. Would you mind rephrasing? >> >> > >> >> > I was talking about a scenario where you want to use the tuned mode to >> >> > achieve the maximum rate because of the device and/or board configuration, >> >> > but the rate is below the point where the controller would need tuning. >> >> > Say the controller needs tuning above 8 Hz but the conditions require >> >> > tuning to achieve more than 5 Hz. In this example, if the device can do >> >> > 6 Hz, spi-max-frequency (in the current form) would be set to 6 Hz, and >> >> > the controller would not enable the tuned mode, leading to problems >> >> > because the inflection point determined from the controller compatible >> >> > of 8 Hz would not have been reached. >> >> >> >> I don't think this is a real situation. If the "conditions", as you say >> >> (ie. PCB routing, mostly) require tuning above 5, then spi-max-frequency >> >> should be 5. >> > >> > Then tuning mode would never be used. >> >> Well, this is exactly what we propose in this series, a way to indicate >> two maximum frequencies, one that just works (like before) and a higher >> frequency that is only reachable after an extra tuning procedure. >> >> > Remember, this is a theoretical world >> > where spi-max-frequency would contain the tuned frequency and the >> > controller was using compatible-specific speed thresholds to determine >> > if tuning was required. >> >> That is not what we are proposing. I don't think indicating the "after >> tuning" frequency in a property that has long been used for an always >> reachable frequency is wise. Hence either the use of an array (the >> second entry could contain a higher frequency) or a secondary >> spi-max-frequency-whatever property. > > I am/was trying to come up with a scenario that would justify the patch > man, stop trying to interpret it as what I want done. Ah :-) Sorry the intention was unclear to me. So what is your preferred take in the end?