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 A9286C77B7C for ; Mon, 8 May 2023 02:36:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229662AbjEHCgi (ORCPT ); Sun, 7 May 2023 22:36:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229577AbjEHCgi (ORCPT ); Sun, 7 May 2023 22:36:38 -0400 Received: from mail-ua1-x92f.google.com (mail-ua1-x92f.google.com [IPv6:2607:f8b0:4864:20::92f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D572411547 for ; Sun, 7 May 2023 19:36:34 -0700 (PDT) Received: by mail-ua1-x92f.google.com with SMTP id a1e0cc1a2514c-77d456fa0dbso1359124241.3 for ; Sun, 07 May 2023 19:36:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1683513392; x=1686105392; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=Dptqg8r0UsWrR3n0HKBRHqVrggh1ivQ7IQr3yU5eDRA=; b=ABTrz6Kj/Gn2qx7IKb+RJD9gjgl2klGp6PIajxFslkI7N+K3PdelDUbcnk+mL+cywm 878ElpMOODX9eaTWjRh6k7XadkTUhqbpSexVNnjzRNotq9TZVozK8oczY60o0a4Tyb4Q fyUqIO+KGn9QKm49zoSyVRHOfuQMjOG6sw9XM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683513392; x=1686105392; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Dptqg8r0UsWrR3n0HKBRHqVrggh1ivQ7IQr3yU5eDRA=; b=Ypk77YwmcCXDPW73gvj2dibDK1unoUcCF3iWbzEQp+u6GGFBqcPVN/WCFpfQLqoq6J Qsf9742Ou9XrSIhNZubChbLTf2iNxXFZFYy3g5Zp/bFCW5qRmv0taoiNrJFP/tm2AH21 4+h8SwYSAuuPkC15VE80527CBL5duqsYPgCicWC6oWDzOCRsVXyA9xdiWjCkMpfTzu45 mk5E5PRfcMTbL0/RdZ9isFBmscYVaHB67CBneTl+cyBamxT19v/lHSSY80W75UZq+ztf o3Tcd9a9UnpuTYNtSIW7dHEf2hmUX8wo2g8jgR8DidBBLKV0rgong8z65keXnlnyd8wL 4QIA== X-Gm-Message-State: AC+VfDwBdWz3POrt/k2WcJVuo9dn0XKSTh3uDA9XAl+FxP0PwJetVfTL r9P0YL/uxC6k02sdqHV/ofABgQMv7pbyjCwPqeWGRw== X-Google-Smtp-Source: ACHHUZ50gsiXHy03kBM5uO2R7gxdLyM9XFldG88yruZf0Axm2n6Ko9rRM3MEf/5h29DiqpiBoLZjjoiG7pZ94fUBcuw= X-Received: by 2002:a67:f353:0:b0:434:8479:1812 with SMTP id p19-20020a67f353000000b0043484791812mr2281063vsm.18.1683513392157; Sun, 07 May 2023 19:36:32 -0700 (PDT) MIME-Version: 1.0 References: <20221018-clk-range-checks-fixes-v4-0-971d5077e7d2@cerno.tech> <20221018-clk-range-checks-fixes-v4-29-971d5077e7d2@cerno.tech> In-Reply-To: <20221018-clk-range-checks-fixes-v4-29-971d5077e7d2@cerno.tech> From: Chen-Yu Tsai Date: Mon, 8 May 2023 10:36:21 +0800 Message-ID: Subject: Re: [PATCH v4 29/68] clk: mediatek: cpumux: Add a determine_rate hook To: Maxime Ripard Cc: Michael Turquette , Stephen Boyd , linux-clk@vger.kernel.org, AngeloGioacchino Del Regno , Matthias Brugger , linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org On Fri, May 5, 2023 at 7:27=E2=80=AFPM Maxime Ripard wr= ote: > > The Mediatek cpumux 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 candidates to > trigger that parent change are either the assigned-clock-parents device > tree property or 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. > > Similarly, it doesn't look like the device tree using that clock driver > uses any of the assigned-clock properties on 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 consumer, the cpufreq driver, assumes the original parent to be the dedicated PLL that drives it. It gets a reference to the original parent with clk_get_parent(). It also gets an intermediate (stable) clock via DT. It does explicit clk_set_parent() calls to switch to/from the stable clock, and does clk_set_rate() on the dedicated PLL in between. So yeah, they only use set_parent hook. > The latter case would be equivalent to setting the determine_rate > implementation to clk_hw_determine_rate_no_reparent(). 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. > > 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. > > Cc: AngeloGioacchino Del Regno > Cc: Matthias Brugger > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-mediatek@lists.infradead.org > Signed-off-by: Maxime Ripard Reviewed-by: Chen-Yu Tsai 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C10AAC77B7D for ; Mon, 8 May 2023 02:37:41 +0000 (UTC) DKIM-Signature: v=1; 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Sun, 07 May 2023 19:36:32 -0700 (PDT) MIME-Version: 1.0 References: <20221018-clk-range-checks-fixes-v4-0-971d5077e7d2@cerno.tech> <20221018-clk-range-checks-fixes-v4-29-971d5077e7d2@cerno.tech> In-Reply-To: <20221018-clk-range-checks-fixes-v4-29-971d5077e7d2@cerno.tech> From: Chen-Yu Tsai Date: Mon, 8 May 2023 10:36:21 +0800 Message-ID: Subject: Re: [PATCH v4 29/68] clk: mediatek: cpumux: Add a determine_rate hook To: Maxime Ripard Cc: Michael Turquette , Stephen Boyd , linux-clk@vger.kernel.org, AngeloGioacchino Del Regno , Matthias Brugger , linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230507_193633_962140_64F4401C X-CRM114-Status: GOOD ( 24.58 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gRnJpLCBNYXkgNSwgMjAyMyBhdCA3OjI34oCvUE0gTWF4aW1lIFJpcGFyZCA8bWF4aW1lQGNl cm5vLnRlY2g+IHdyb3RlOgo+Cj4gVGhlIE1lZGlhdGVrIGNwdW11eCBjbG9jayBpbXBsZW1lbnRz IGEgbXV4IHdpdGggYSBzZXRfcGFyZW50IGhvb2ssIGJ1dAo+IGRvZXNuJ3QgcHJvdmlkZSBhIGRl dGVybWluZV9yYXRlIGltcGxlbWVudGF0aW9uLgo+Cj4gVGhpcyBpcyBhIGJpdCBvZGQsIHNpbmNl IHNldF9wYXJlbnQoKSBpcyB0aGVyZSB0bywgYXMgaXRzIG5hbWUgaW1wbGllcywKPiBjaGFuZ2Ug dGhlIHBhcmVudCBvZiBhIGNsb2NrLiBIb3dldmVyLCB0aGUgbW9zdCBsaWtlbHkgY2FuZGlkYXRl cyB0bwo+IHRyaWdnZXIgdGhhdCBwYXJlbnQgY2hhbmdlIGFyZSBlaXRoZXIgdGhlIGFzc2lnbmVk LWNsb2NrLXBhcmVudHMgZGV2aWNlCj4gdHJlZSBwcm9wZXJ0eSBvciBhIGNhbGwgdG8gY2xrX3Nl dF9yYXRlKCksIHdpdGggZGV0ZXJtaW5lX3JhdGUoKQo+IGZpZ3VyaW5nIG91dCB3aGljaCBwYXJl bnQgaXMgdGhlIGJlc3Qgc3VpdGVkIGZvciBhIGdpdmVuIHJhdGUuCj4KPiBUaGUgb3RoZXIgdHJp Z2dlciB3b3VsZCBiZSBhIGNhbGwgdG8gY2xrX3NldF9wYXJlbnQoKSwgYnV0IGl0J3MgZmFyIGxl c3MKPiB1c2VkLCBhbmQgaXQgZG9lc24ndCBsb29rIGxpa2UgdGhlcmUncyBhbnkgb2J2aW91cyB1 c2VyIGZvciB0aGF0IGNsb2NrLgo+Cj4gU2ltaWxhcmx5LCBpdCBkb2Vzbid0IGxvb2sgbGlrZSB0 aGUgZGV2aWNlIHRyZWUgdXNpbmcgdGhhdCBjbG9jayBkcml2ZXIKPiB1c2VzIGFueSBvZiB0aGUg YXNzaWduZWQtY2xvY2sgcHJvcGVydGllcyBvbiB0aGF0IGNsb2NrLgo+Cj4gU28sIHRoZSBzZXRf cGFyZW50IGhvb2sgaXMgZWZmZWN0aXZlbHkgdW51c2VkLCBwb3NzaWJseSBiZWNhdXNlIG9mIGFu Cj4gb3ZlcnNpZ2h0LiBIb3dldmVyLCBpdCBjb3VsZCBhbHNvIGJlIGFuIGV4cGxpY2l0IGRlY2lz aW9uIGJ5IHRoZQo+IG9yaWdpbmFsIGF1dGhvciB0byBhdm9pZCBhbnkgcmVwYXJlbnRpbmcgYnV0 IHRocm91Z2ggYW4gZXhwbGljaXQgY2FsbCB0bwo+IGNsa19zZXRfcGFyZW50KCkuCgpUaGUgY29u c3VtZXIsIHRoZSBjcHVmcmVxIGRyaXZlciwgYXNzdW1lcyB0aGUgb3JpZ2luYWwgcGFyZW50IHRv IGJlCnRoZSBkZWRpY2F0ZWQgUExMIHRoYXQgZHJpdmVzIGl0LiBJdCBnZXRzIGEgcmVmZXJlbmNl IHRvIHRoZSBvcmlnaW5hbApwYXJlbnQgd2l0aCBjbGtfZ2V0X3BhcmVudCgpLiBJdCBhbHNvIGdl dHMgYW4gaW50ZXJtZWRpYXRlIChzdGFibGUpIGNsb2NrCnZpYSBEVC4gSXQgZG9lcyBleHBsaWNp dCBjbGtfc2V0X3BhcmVudCgpIGNhbGxzIHRvIHN3aXRjaCB0by9mcm9tIHRoZQpzdGFibGUgY2xv Y2ssIGFuZCBkb2VzIGNsa19zZXRfcmF0ZSgpIG9uIHRoZSBkZWRpY2F0ZWQgUExMIGluIGJldHdl ZW4uCgpTbyB5ZWFoLCB0aGV5IG9ubHkgdXNlIHNldF9wYXJlbnQgaG9vay4KCj4gVGhlIGxhdHRl ciBjYXNlIHdvdWxkIGJlIGVxdWl2YWxlbnQgdG8gc2V0dGluZyB0aGUgZGV0ZXJtaW5lX3JhdGUK PiBpbXBsZW1lbnRhdGlvbiB0byBjbGtfaHdfZGV0ZXJtaW5lX3JhdGVfbm9fcmVwYXJlbnQoKS4g SW5kZWVkLCBpZiBubwo+IGRldGVybWluZV9yYXRlIGltcGxlbWVudGF0aW9uIGlzIHByb3ZpZGVk LCBjbGtfcm91bmRfcmF0ZSgpICh0aHJvdWdoCj4gY2xrX2NvcmVfcm91bmRfcmF0ZV9ub2xvY2so KSkgd2lsbCBjYWxsIGl0c2VsZiBvbiB0aGUgcGFyZW50IGlmCj4gQ0xLX1NFVF9SQVRFX1BBUkVO VCBpcyBzZXQsIGFuZCB3aWxsIG5vdCBjaGFuZ2UgdGhlIGNsb2NrIHJhdGUKPiBvdGhlcndpc2Uu Cj4KPiBBbmQgaWYgaXQgd2FzIGFuIG92ZXJzaWdodCwgdGhlbiB3ZSBhcmUgYXQgbGVhc3QgZXhw bGljaXQgYWJvdXQgb3VyCj4gYmVoYXZpb3Igbm93IGFuZCBpdCBjYW4gYmUgZnVydGhlciByZWZp bmVkIGRvd24gdGhlIGxpbmUuCj4KPiBDYzogQW5nZWxvR2lvYWNjaGlubyBEZWwgUmVnbm8gPGFu Z2Vsb2dpb2FjY2hpbm8uZGVscmVnbm9AY29sbGFib3JhLmNvbT4KPiBDYzogTWF0dGhpYXMgQnJ1 Z2dlciA8bWF0dGhpYXMuYmdnQGdtYWlsLmNvbT4KPiBDYzogbGludXgtYXJtLWtlcm5lbEBsaXN0 cy5pbmZyYWRlYWQub3JnCj4gQ2M6IGxpbnV4LW1lZGlhdGVrQGxpc3RzLmluZnJhZGVhZC5vcmcK PiBTaWduZWQtb2ZmLWJ5OiBNYXhpbWUgUmlwYXJkIDxtYXhpbWVAY2Vybm8udGVjaD4KClJldmll d2VkLWJ5OiBDaGVuLVl1IFRzYWkgPHdlbnN0QGNocm9taXVtLm9yZz4KCl9fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LWFybS1rZXJuZWwgbWFpbGlu ZyBsaXN0CmxpbnV4LWFybS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMu aW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LWFybS1rZXJuZWwK