From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9CBD03C13EE; Fri, 20 Mar 2026 14:29:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774016949; cv=none; b=WJ1dHpu4l4l4XG96LiA8VLbb5nDYb/OZlxSLu/pq9VmRvWKdD0wxih8H0BD68t3ON3Lain7n4oweVDpuf79phpllg39BYBUpRwRdyLDVBi25r9NGv+qyjB3Ylpo7Olf4vSLIwPJrvJUNs3apOLSAQiQ6V13PFY8OLyvasmP8u/M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774016949; c=relaxed/simple; bh=Fmoo0DapoaPJhMqEqYq5deJO3MZhRATe1HKMHY1bWos=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mbCcwCyYu72NQZlX7bOzPUFAG9sZKHjaLm5azyI3TG3Z+r4yK7GHk62fsKMY3KpWkpdxMIV/IISPC6+zc4PxPGjrqGup7H6IjwoFJizU+4Mhf2koiw0p39rFYPn3gmmuhjNsxRPi+ku+Ig9lJLa0QFVQ5eOfrcIgVKQE3ogd1X8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Xpu4/Ke/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Xpu4/Ke/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22F64C4CEF7; Fri, 20 Mar 2026 14:29:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774016949; bh=Fmoo0DapoaPJhMqEqYq5deJO3MZhRATe1HKMHY1bWos=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Xpu4/Ke/r2xeZNNp+ln9MluR+qPoLsC4wTeMEuvyBh2xKgAKiJsaijwi2p1GFYOx4 vErXICLx6ISViNOiVE4n4DAJkNuXCEZxbbFa1ZJR6EifN957nPixIFSpFImxwKCLFB EfzuWAigmZwGlp6xfBq00/m0hqtaVVo3sCrra+MZBP8toEbZZhxNxAYrye4ITBO2h3 46gSm/RoFGOlHE4/35hSjQoiX6we4IggZGMFc45RVFOiKJ24dTypnAsjKsAuPRjPVT tdHAJ5Mi3YVogO/0dIkncWJOhkbyogGIupU4tCPfvgcZewqHAF6lIYnDe4zEA9PbNl dzocemjSO901g== Date: Fri, 20 Mar 2026 15:29:06 +0100 From: Maxime Ripard To: Brian Masney Cc: Michael Turquette , Stephen Boyd , Alberto Ruiz , linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 2/7] clk: test: introduce test suite for sibling rate changes on a divider Message-ID: <20260320-sticky-overjoyed-pheasant-9bb63c@houat> References: <20260313-clk-scaling-v6-0-ce89968c5247@redhat.com> <20260313-clk-scaling-v6-2-ce89968c5247@redhat.com> <20260319-spry-incredible-dinosaur-e2d9da@houat> <20260320-daring-smiling-sturgeon-fbac05@houat> Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha384; protocol="application/pgp-signature"; boundary="q766sjjelagi666l" Content-Disposition: inline In-Reply-To: --q766sjjelagi666l Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v6 2/7] clk: test: introduce test suite for sibling rate changes on a divider MIME-Version: 1.0 On Fri, Mar 20, 2026 at 09:08:29AM -0400, Brian Masney wrote: > On Fri, Mar 20, 2026 at 9:03=E2=80=AFAM Maxime Ripard wrote: > > On Thu, Mar 19, 2026 at 07:08:07AM -0400, Brian Masney wrote: > > > On Thu, Mar 19, 2026 at 5:10=E2=80=AFAM Maxime Ripard wrote: > > > > On Fri, Mar 13, 2026 at 12:43:09PM -0400, Brian Masney wrote: > > > > Anyway, what I'm trying to say at least is that, at least, we shoul= dn't > > > > frame it as a guarantee the framework provides, because it's really= not > > > > the case. > > > > > > I see what you are saying, however these are divider tests, and this > > > is the way that clk-divider works. > > > > Yes, this is an undocumented behaviour of *clk-divider*. clk-divider is > > not the only divider implementation. If anything, it's the reference > > implementation, but that's pretty much it. > > > > So when you say: > > > > > +/* > > > + * Test that, for a parent with two divider-only children with CLK_S= ET_RATE_PARENT set > > > + * and one requests a rate compatible with the existing parent rate,= the parent and > > > + * sibling rates are not affected. > > > + */ > > > > And > > > > > I want to demonstrate that the clk core is being called, and that > > > ultimately the correct dividers are computed. > > > > This is only true for one implementation, and so far has been considered > > an implementation detail. It's not something you can generalize. > > > > And to make my point clearer, I wasn't saying this test shouldn't be > > there, I was saying we shouldn't do and document that generalization. > > > > > For example, on patch 7 of this series: > > > > > > - Parent, child1 and child2 all start out at 24 MHz. > > > - child1 requests 32 MHz. > > > - Parent is changed to 96 MHz, child1 at 32 MHz, child2 stays at 24 M= Hz. > > > > > > Child2 keeps the same rate, however the tests show that the clk is > > > actually updated since the divider is changed from 1 to 4 after this > > > operation. This is to simulate what would be programmed into a > > > register for real hardware. > > > > > > I can drop the expects for the dividers if you really want in the next > > > version. Personally, I see value since these are divider-specific > > > tests. > > > > Not really, these tests are clk-divider tests, nothing more. >=20 > OK, I'll drop the checks for the actual dividers in the next version. It really wasn't the point I was trying to make. It's fine to have that test as a clk-divider test, but we should document it as just that, nothing more. Maxime --q766sjjelagi666l Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJUEABMJAB0WIQTkHFbLp4ejekA/qfgnX84Zoj2+dgUCab1ZsgAKCRAnX84Zoj2+ duALAYCa+UN7UTrR4kvNIOWVtn5jHwylzRHeP/MWL4w5BvjUROH2aMko96Ng4GoI h3dCV0MBf2z0RD4YB+LiI1jxYZP/J+A7EPNx0SNA6cS0Ygt6vHm/5zu751l39pON FIZuKaFSHQ== =9y03 -----END PGP SIGNATURE----- --q766sjjelagi666l--