From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.153.233]) (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 AFA272EEE6E; Fri, 5 Jun 2026 07:18:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=68.232.153.233 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780643894; cv=none; b=cyxF6p74sUfe243AWtBPfVqtQKOFnLW+W8k+zriUAKkzfitnEiaGdKPsIH7l3ppFwClgFky8SFrhf+VsGTwTOSiufx+Q0Idj/glqCcEMx5AwVoCHkEUnr0/LAYstvFdmLk761bT8UyMCOGFClAJw7NKMA1boHyHcr8HUqzCZUVI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780643894; c=relaxed/simple; bh=jcrToytibwcBAYhSAoNEEpY1rO4Mmvre/yeNqvlg5Fw=; h=Date:From:To:CC:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BuSip+yPtnQUs5Sbi6cwbKkZd0jQsmEvFMNydOeWrhGSC0Dk0Vi8j+i4UbggLQBfhJXeK7xh2Ty+j5RuBhAcBJ4j3PDSD+X1tkeguqZRr0jh4cHVFTUW/tQhudzcrXDtfMemUlK4y0B4qo//n3NasFkTczfOg4OCEjNTK8uXD3U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=microchip.com; spf=pass smtp.mailfrom=microchip.com; dkim=pass (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b=b7+3e0Cu; arc=none smtp.client-ip=68.232.153.233 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=microchip.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=microchip.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b="b7+3e0Cu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1780643894; x=1812179894; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=jcrToytibwcBAYhSAoNEEpY1rO4Mmvre/yeNqvlg5Fw=; b=b7+3e0Cu12maMeGmtkn2FIkQrGXzzBl5l0X//7dAub2oRHPG6n0oXHZT 5Cox8KnyZi4u+q03plJ5I86ZvjNFlKqtnehUPQlVFy7lVs+YXffio1kkV 8LlUs/hP6T3xxzQvnoB/JXVgcF46lGua5z393XkeYq+5lWs2eF4u7TGRe s+/uCKPqv9/G0WNow8L+6IT3R5OzAquszt2/e5Rp9cQLmiOps3DAwEqV+ z31Glm0irGonLruUf+3Y2sHGPg2kpOa3tOUXirIm4yZNlg8+vJgL4WmAL 2ZXPsUFnwiSQwByhOXRtskeuj1r3ON0UKL6RQeK0oZ1AeSaom0NcMpfkZ A==; X-CSE-ConnectionGUID: GTxp86iZTpGaNRQZ6+6kdA== X-CSE-MsgGUID: QRxBKdmdRiqD2ogDiIat/g== X-IronPort-AV: E=Sophos;i="6.24,188,1774335600"; d="asc'?scan'208";a="58640353" X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa3.microchip.iphmx.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jun 2026 00:18:07 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.87.72) by chn-vm-ex4.mchp-main.com (10.10.87.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.2.2562.41; Fri, 5 Jun 2026 00:18:06 -0700 Received: from wendy (10.10.85.11) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.58 via Frontend Transport; Fri, 5 Jun 2026 00:18:02 -0700 Date: Fri, 5 Jun 2026 08:17:18 +0100 From: Conor Dooley To: Miquel Raynal CC: Conor Dooley , Santhosh Kumar K , , , , , , , , , , , , , , , , Subject: Re: [PATCH v3 01/13] spi: dt-bindings: allow spi-max-frequency to specify a frequency pair Message-ID: <20260605-regulate-crawling-253c6d6bd971@wendy> 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> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="zUWntl/XEoxjT7CW" Content-Disposition: inline In-Reply-To: <87a4t9wl7r.fsf@bootlin.com> --zUWntl/XEoxjT7CW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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: >=20 > > 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 controlle= r 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? > >> >> >>=20 > >> >> >> I do not actually expect any tuned mode/frequency to be mandator= y. > >> >> > > >> >> > 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. > >> >>=20 > >> >> 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 configur= ation, > >> > but the rate is below the point where the controller would need tuni= ng. > >> > 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 compatib= le > >> > 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-frequen= cy > >> should be 5. > > > > Then tuning mode would never be used. >=20 > 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. >=20 > > 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. >=20 > 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. --zUWntl/XEoxjT7CW Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCaiJ3+wAKCRB4tDGHoIJi 0tz4AP97UBfrz9S9QPKf/ELSWSCSJG0AKrTL2Ilbca63w1hqBwEAmh8dIG97WI0/ 6CTKNcnF/fGzd+mNaOA+H2isiryDNgs= =GMVI -----END PGP SIGNATURE----- --zUWntl/XEoxjT7CW--