From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B83E2C77B70 for ; Tue, 11 Apr 2023 13:09:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229700AbjDKNJ6 (ORCPT ); Tue, 11 Apr 2023 09:09:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230047AbjDKNJv (ORCPT ); Tue, 11 Apr 2023 09:09:51 -0400 Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [IPv6:2001:4b98:dc4:8::227]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1E014690; Tue, 11 Apr 2023 06:09:47 -0700 (PDT) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 8667320007; Tue, 11 Apr 2023 13:09:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1681218585; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zj1JtAKrv3GVkrzExsf9B7vpxAMSpGNgfjgQje0eTak=; b=oNG2Rb7etLGd3op/Iz2fmq0xokA2awaHaTUwmpMIqfWRcdiVNffJhH1OiD/NJa8U8VhbyA yF9MXtYH8Fxz3M+cAq/7V/oq1xoDx4mXB50I/MCViACuf5Xj/3sm+jiFSUhQyd/GFiKSU+ MvbhXoQ5xcQFvUgIZ6glZLEM1HPSvT3ZkSE8cIw3GiRKuf3ey7u+ch+9vo/URZlNg8hBkX sdQ/9ZojYLUArwz1K4ERP3d5/cBFRF6/83yyqSdXppNVR0gRdgwuMipAeMDZ8IGKN7s335 n6r/K2t/A0PaaBtBH3FUkAWJV3CrDikEbkeZlUHa/BD6XrUBmGFFsgVYyetBaQ== Date: Tue, 11 Apr 2023 15:09:30 +0200 From: Miquel Raynal To: Geert Uytterhoeven Cc: Maxime Ripard , Michael Turquette , Stephen Boyd , Andreas =?UTF-8?B?RsOkcmJlcg==?= , Manivannan Sadhasivam , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Max Filippov , Charles Keepax , Richard Fitzgerald , Maxime Coquelin , Alexandre Torgue , Luca Ceresoli , David Lechner , Sekhar Nori , Abel Vesa , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Matthias Brugger , Geert Uytterhoeven , Dinh Nguyen , Peter De Schrijver , Prashant Gaikwad , Thierry Reding , Jonathan Hunter , Ulf Hansson , Linus Walleij , David Airlie , Daniel Vetter , Vinod Koul , Kishon Vijay Abraham I , Alessandro Zummo , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , Paul Cercueil , Orson Zhai , Baolin Wang , Chunyan Zhang , linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org, AngeloGioacchino Del Regno , linux-arm-kernel@lists.infradead.org, linux-actions@lists.infradead.org, patches@opensource.cirrus.com, linux-stm32@st-md-mailman.stormreply.com, linux-mediatek@lists.infradead.org, linux-renesas-soc@vger.kernel.org, linux-tegra@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-phy@lists.infradead.org, linux-rtc@vger.kernel.org, linux-sunxi@lists.linux.dev, alsa-devel@alsa-project.org, linux-mips@vger.kernel.org, Gareth Williams , Herve Codina , Ralph Siemsen Subject: Re: [PATCH v3 28/65] clk: renesas: r9a06g032: Add a determine_rate hook Message-ID: <20230411150930.4fb22d7e@xps-13> In-Reply-To: References: <20221018-clk-range-checks-fixes-v3-0-9a1358472d52@cerno.tech> <20221018-clk-range-checks-fixes-v3-28-9a1358472d52@cerno.tech> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Hi Geert & Maxime, geert@linux-m68k.org wrote on Tue, 11 Apr 2023 12:27:38 +0200: > CC Gareth, Herv=C3=A9, Miquel, Ralph >=20 > On Tue, Apr 4, 2023 at 2:44=E2=80=AFPM Maxime Ripard = wrote: > > The Renesas r9a06g032 bitselect clock implements a mux with a set_parent > > hook, but doesn't provide a determine_rate implementation. > > > > This is a bit odd, since set_parent() is there to, as its name implies, > > change the parent of a clock. However, the most likely candidate to > > trigger that parent change is a call to clk_set_rate(), with > > determine_rate() figuring out which parent is the best suited for a > > given rate. > > > > The other trigger would be a call to clk_set_parent(), but it's far less > > used, and it doesn't look like there's any obvious user for that clock. > > > > So, the set_parent hook is effectively unused, possibly because of an > > oversight. However, it could also be an explicit decision by the > > original author to avoid any reparenting but through an explicit call to > > clk_set_parent(). > > > > The latter case would be equivalent to setting the flag > > CLK_SET_RATE_NO_REPARENT, together with setting our determine_rate hook > > to __clk_mux_determine_rate(). Indeed, if no determine_rate > > implementation is provided, clk_round_rate() (through > > clk_core_round_rate_nolock()) will call itself on the parent if > > CLK_SET_RATE_PARENT is set, and will not change the clock rate > > otherwise. __clk_mux_determine_rate() has the exact same behavior when > > CLK_SET_RATE_NO_REPARENT is set. > > > > And if it was an oversight, then we are at least explicit about our > > behavior now and it can be further refined down the line. > > > > Signed-off-by: Maxime Ripard =20 >=20 > LGTM, so > Reviewed-by: Geert Uytterhoeven I searched for 'possible callers', I didn't find any places where this would be used on the consumer side. However, downstream, there is a rzn1-clock-bitselect.c clock driver which states: + * This clock provider handles the case of the RZN1 where you have periphe= rals + * that have two potential clock source and two gates, one for each of the + * clock source - the used clock source (for all sub clocks) is selected b= y a + * single bit. + * That single bit affects all sub-clocks, and therefore needs to change t= he + * active gate (and turn the others off) and force a recalculation of the = rates. I don't know how much of this file has been upstreamed (under a different form) but this might very well be related to the fact that reparenting in some cases would be a major issue and thus needs to be avoided unless done on purpose (guessing?). Maybe Ralph can comment, but for what I understand, Reviewed-by: Miquel Raynal > But I do not have the hardware. >=20 > > --- a/drivers/clk/renesas/r9a06g032-clocks.c > > +++ b/drivers/clk/renesas/r9a06g032-clocks.c > > @@ -1121,6 +1121,7 @@ static int r9a06g032_clk_mux_set_parent(struct cl= k_hw *hw, u8 index) > > } > > > > static const struct clk_ops clk_bitselect_ops =3D { > > + .determine_rate =3D __clk_mux_determine_rate, > > .get_parent =3D r9a06g032_clk_mux_get_parent, > > .set_parent =3D r9a06g032_clk_mux_set_parent, > > }; > > @@ -1145,7 +1146,7 @@ r9a06g032_register_bitsel(struct r9a06g032_priv *= clocks, > > > > init.name =3D desc->name; > > init.ops =3D &clk_bitselect_ops; > > - init.flags =3D CLK_SET_RATE_PARENT; > > + init.flags =3D CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT; > > init.parent_names =3D names; > > init.num_parents =3D 2; > > =20 >=20 > Gr{oetje,eeting}s, >=20 > Geert >=20 Thanks, Miqu=C3=A8l