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 X-Spam-Level: X-Spam-Status: No, score=-14.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7F15C43613 for ; Sat, 22 Jun 2019 21:42:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC419205ED for ; Sat, 22 Jun 2019 21:42:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="D1cL17iX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726370AbfFVVmQ (ORCPT ); Sat, 22 Jun 2019 17:42:16 -0400 Received: from mail-ot1-f68.google.com ([209.85.210.68]:36795 "EHLO mail-ot1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726286AbfFVVmQ (ORCPT ); Sat, 22 Jun 2019 17:42:16 -0400 Received: by mail-ot1-f68.google.com with SMTP id r6so9802456oti.3 for ; Sat, 22 Jun 2019 14:42:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=sA7VtGDWxs1PvSfqLqhiT/lLON+GJR9IC0w/w0nnIBM=; b=D1cL17iXU3Cpd4uakFKBHIz8GMmCUH5nrcvqcDGaon2xlXNfslYTXhkTtRifrfVG/Z G3YYQXFKfq/+Dzt6rVrp1JNi0dLGFgYpyQfX92jwIdyFFRA4EhB8/6pytGmN8emCTaz2 dHCumVKE9pU4EMrF8d+UvZG0Zn8kl4ol0gtTlfQnk5ahVtCY/D3mSFoM2ZQfAvnt6nie 20oM8ReSSzw4+m1p7ATYl23pNdKay5szlUme+U+O32iMW9x/3sYPUqw7+hLBVOIT4FCr qCD6JZCSHHdmlu8DsAD38HOW8qHTyZcrVH361/E+ThQK36QMPfbZibbr5pfFWXfljSSh STQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=sA7VtGDWxs1PvSfqLqhiT/lLON+GJR9IC0w/w0nnIBM=; b=MN1Mx97CX3mVM+L1UWXyW6TQotZfIKurW4e++iEPDvJdwksXu/0irOuOmS6nvmVZCt KXULP7FxiBWe8QUtnAtblPVBOPc/58mvLCsHUke4f7bK1YS4TB0NBN6GqBAuJjMHBz+F FJkmrmdNnFr71vziTlX1S48gQmVoyNheX4iHOFK1heRcvQtE6tAF5W1T8a8r84EkgMvk E3DoyE4DmN1SOz1Dsw9rakfW535zG7/jslbz46750F+3gkQR7uQIZPheSZGjTuvXuFyS h2Xqj+bpdugGUAcvXdeNH/8DEfkFg/N100oU9mpInaEAl3e6ZaW5G2UxSzilf9vDHBS/ OrvA== X-Gm-Message-State: APjAAAXtGc0G0AKd4EAdSjOvCyB60y6BAFRW7RO6/YaNgi0UQDmK6KTu DTTD3F1HaQl+zKkzCzZraq3SAaLJzA8mTAMn+APmjQ== X-Google-Smtp-Source: APXvYqw1/VjNqqLNPPsWgbEg0uYYz6v4taHFtKPb4IB3PluWVhoRJoIluqDxel0TkBM5NJ24l3ImDzXl+daUjAUK8X0= X-Received: by 2002:a05:6830:160c:: with SMTP id g12mr21774228otr.231.1561239734747; Sat, 22 Jun 2019 14:42:14 -0700 (PDT) MIME-Version: 1.0 References: <20190622003449.33707-1-saravanak@google.com> <20190622003449.33707-3-saravanak@google.com> In-Reply-To: From: Saravana Kannan Date: Sat, 22 Jun 2019 14:41:39 -0700 Message-ID: Subject: Re: [PATCH v1 2/3] OPP: Add function to look up required OPP's for a given OPP To: cwchoi00@gmail.com Cc: MyungJoo Ham , Kyungmin Park , Chanwoo Choi , Viresh Kumar , Nishanth Menon , Stephen Boyd , "Rafael J. Wysocki" , Android Kernel Team , Linux PM list , linux-kernel Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 22, 2019 at 4:50 AM Chanwoo Choi wrote: > > Hi, > > Absolutely, I like this approach. I think that it is necessary to make > the connection > between frequencies of devices. Happy to hear that. > But, I have a question on below. > > 2019=EB=85=84 6=EC=9B=94 22=EC=9D=BC (=ED=86=A0) =EC=98=A4=EC=A0=84 9:35,= Saravana Kannan =EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84= =B1: > > > > Add a function that allows looking up required OPPs given a source OPP > > table, destination OPP table and the source OPP. > > > > Signed-off-by: Saravana Kannan > > --- > > drivers/opp/core.c | 54 ++++++++++++++++++++++++++++++++++++++++++ > > include/linux/pm_opp.h | 11 +++++++++ > > 2 files changed, 65 insertions(+) > > > > diff --git a/drivers/opp/core.c b/drivers/opp/core.c > > index 74c7bdc6f463..4f7870bffbf8 100644 > > --- a/drivers/opp/core.c > > +++ b/drivers/opp/core.c > > @@ -1830,6 +1830,60 @@ void dev_pm_opp_put_genpd_virt_dev(struct opp_ta= ble *opp_table, > > dev_err(virt_dev, "Failed to find required device entry= \n"); > > } > > > > +/** > > + * dev_pm_opp_xlate_opp() - Find required OPP for src_table OPP. > > + * @src_table: OPP table which has dst_table as one of its required OP= P table. > > + * @dst_table: Required OPP table of the src_table. > > + * @pstate: OPP of the src_table. > > + * > > + * This function returns the OPP (present in @dst_table) pointed out b= y the > > + * "required-opps" property of the OPP (present in @src_table). > > + * > > + * The callers are required to call dev_pm_opp_put() for the returned = OPP after > > + * use. > > + * > > + * Return: destination table OPP on success, otherwise NULL on errors. > > + */ > > +struct dev_pm_opp *dev_pm_opp_xlate_opp(struct opp_table *src_table, > > + struct opp_table *dst_table, > > + struct dev_pm_opp *src_opp) > > +{ > > + struct dev_pm_opp *opp, *dest_opp =3D NULL; > > + int i; > > + > > + if (!src_table || !dst_table || !src_opp) > > + return NULL; > > + > > + for (i =3D 0; i < src_table->required_opp_count; i++) { > > + if (src_table->required_opp_tables[i]->np =3D=3D dst_ta= ble->np) > > + break; > > + } > > + > > + if (unlikely(i =3D=3D src_table->required_opp_count)) { > > + pr_err("%s: Couldn't find matching OPP table (%p: %p)\n= ", > > + __func__, src_table, dst_table); > > + return NULL; > > + } > > + > > + mutex_lock(&src_table->lock); > > + > > + list_for_each_entry(opp, &src_table->opp_list, node) { > > + if (opp =3D=3D src_opp) { > > + dest_opp =3D opp->required_opps[i]; > > Correct me if I am wrong. This patch assume that 'i' index is same on bet= ween > [1] and [2]. But in order to guarantee this assumption, all OPP entries > in the same opp_table have to have the same number of 'required-opps' pro= perties > and keep the sequence among 'required-opps' entries. > > [1] src_table->required_opp_tables[i]->np > [2] opp->required_opps[I]; > > For example, three OPP entries in the 'parent_bus_opp' > have the different sequence of 'required-opps' and the different > number of 'required-opps'. Is it no problem? > > parent_bus_opp: opp_table { > compatible =3D "operating-points-v2"; > > opp2 { > opp-hz =3D /bits/ 64 <200000>; > required-opps =3D <&child_bus_a_opp2>, <&child_bus_b_opp2>, > <&child_bus_c_opp2>; > }; > > opp1 { > opp-hz =3D /bits/ 64 <200000>; > // change the sequence between child_bus_b_opp2 and child_bus_c_= opp2 > required-opps =3D <&child_bus_a_opp2>, <&child_bus_c_opp2>, > <&child_bus_b_opp2> > }; > > opp0 { > opp-hz =3D /bits/ 64 <200000>; > // missing 'child_bus_a_opp2' > required-opps =3D <&child_bus_c_opp2>, <&child_bus_b_opp2> > }; > > } > I get your question. If I'm not mistaken the OPP framework DT parsing code makes the assumption that the required-opps list has the phandles in the same order for each "row" in the OPP table. It actually only looks at the first OPP entry to figure out the list of required OPP tables. Technically one can write code to deal with random order of the required-opp list, but doesn't seem like that's worth it because there's no need to have that order all mixed up in DT. And even if someone wants to add support for that, I don't think improving the DT parsing to handle random order would be part of this patch series. -Saravana > -- > Best Regards, > Chanwoo Choi > > -- > To unsubscribe from this group and stop receiving emails from it, send an= email to kernel-team+unsubscribe@android.com. >