From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-04.galae.net (smtpout-04.galae.net [185.171.202.116]) (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 A5AF1382289; Fri, 5 Jun 2026 06:33:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.171.202.116 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780641185; cv=none; b=mlr2Yg8ctLtuT0QeP4bxjSb4+GL14AQ1MyJaLj8hkpQmxZGwdPP1W5Ht+vSePQDH5z9oCWNv1kHvAYI3oYNEol2tpLqGDjF5oMU6F/QHd0GTb76yZ0K6zwd9EXjLKqeH67T1Leu0Roin7XWSmkNOOuUB05kr+pQkOCB1FmTd3tg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780641185; c=relaxed/simple; bh=oZ+ZvFYXgt3BlDHLx3H6UKrGgUH+GXfiB8/jp4bvNtM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=EazN1BqIcCCkXb6715A34hOvHU3JVaLWlLFPX5anbbWOHsP/rVgj68h2rotPur3UimbaxuxSInRT1fajB2bI8Byxd5n/v9KFcMGCLh81G4QNwFuvbuLRAey2Tlb1wrJKI2J0sZMn1UofSqdc0wBhmfWEOkp/qv1+Xcd75419DdY= 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=sH7jIIJW; arc=none smtp.client-ip=185.171.202.116 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="sH7jIIJW" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id 7D854C5846E; Fri, 5 Jun 2026 06:33:02 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id E41095FED1; Fri, 5 Jun 2026 06:33:02 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 9172B106A1D96; Fri, 5 Jun 2026 08:32:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1780641182; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=oZ+ZvFYXgt3BlDHLx3H6UKrGgUH+GXfiB8/jp4bvNtM=; b=sH7jIIJWFPZR4hP+gJQg9HmaSqE1LeB2WEN6Po/fsKY9cA/HNSdDG0U1CgzeUcCesWx90b lSCBbKqwsoc9zmbFlWtMDWn4qHzjZXHzfecQeiVqxOIfXx/dOtyaCPHB25uJMMGJSmFmzn Qft13lRSJQi8vRmG9Bfg2fuLF/HWp3Dms3fdfUsP+YMydeKnTGwZwRFX9b86yMkphOlM7p 9x18LnAC/szhbJNdYaqZpyc7DWog5+nX8Eh2NsgnONIUpW5v0+01/3E5Ljjp/HtzAhvIMI MtA3y4trl10T711ZDtIOHTAh4oWqLj0RMj4Qd53Pl7BgwXPXKoqtRxzqAwfFkg== From: Miquel Raynal To: Conor Dooley Cc: Santhosh Kumar K , broonie@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, richard@nod.at, vigneshr@ti.com, pratyush@kernel.org, mwalle@kernel.org, takahiro.kuwano@infineon.com, linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, praneeth@ti.com, u-kumar1@ti.com, a-dutta@ti.com Subject: Re: [PATCH v3 01/13] spi: dt-bindings: allow spi-max-frequency to specify a frequency pair In-Reply-To: <20260604-shrunk-acclaim-25368d7ad63e@spud> (Conor Dooley's message of "Thu, 4 Jun 2026 09:36:49 +0100") References: <20260527175527.2247679-2-s-k6@ti.com> <20260528-clergyman-kindling-20971775ba78@spud> <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> User-Agent: mu4e 1.12.7; emacs 30.2 Date: Fri, 05 Jun 2026 08:32:56 +0200 Message-ID: <87a4t9wl7r.fsf@bootlin.com> Precedence: bulk X-Mailing-List: linux-spi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 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, >>=20 >> >> >> > 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 th= e "base >> >> >> > speed" of the controller but because of board routing or device >> >> >> > capability that the tuned mode is still required, right? >> >> >>=20 >> >> >> 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 th= at it >> >> > should be a required property in a binding. >> >>=20 >> >> Yes I misunderstood the term indeed. However I still fail to catch wh= at >> >> 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 configurat= ion, >> > 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. >>=20 >> 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. Thanks, Miqu=C3=A8l