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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 93535C04EB5 for ; Fri, 7 Feb 2020 14:11:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D03321775 for ; Fri, 7 Feb 2020 14:11:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RiThLvRa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726860AbgBGOLH (ORCPT ); Fri, 7 Feb 2020 09:11:07 -0500 Received: from mail-io1-f42.google.com ([209.85.166.42]:41641 "EHLO mail-io1-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726798AbgBGOLH (ORCPT ); Fri, 7 Feb 2020 09:11:07 -0500 Received: by mail-io1-f42.google.com with SMTP id m25so2299624ioo.8; Fri, 07 Feb 2020 06:11:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=hwAVc8buUw/sXi4l5AGn5t8v/Of6qVn4+kM7CimiWbs=; b=RiThLvRaLcY+VY1nLgFfR8Wc7ihO/J62UUWv3LUtuTcFUBZfZCQF9Db7FXUxLoxK1C MvU9Z3ZTiELbj071a88cJKvn106vCNg7tFw+35XrbOrgfQ1m7ZBDZ9tlc1Mt+HV4TgfZ xBsn5/FxnhZ7cZqQmjCc03kKSe0O1SJl7A+E41hp5Qg58Sj8/eixwP9rZrj2fJT5Ps2+ rHVvQYpZMaOqfhMCiKWYivGnJY+rV38VK1kfUfoWETqfaa2ZUU/U/feyqdsy0tTiWGtw arb9C21VMXHDNZAlH6y/vlbRmDtE59FkdRmkyxayDazwYJuuUE8gs6/lfwQsR0SILMDV 0yew== 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; bh=hwAVc8buUw/sXi4l5AGn5t8v/Of6qVn4+kM7CimiWbs=; b=h6E6I1tkZoBDrMGlVRcuvuI9SPyWwrZLajUI4uck9J4Bwlj0DtQVsUPwuleTMuwZy/ dI8OZ9BVkcnBLHe7aDWoTH1dTPbUJDS4fOAP0DzUv96dIcN0vT8w3lnEMvPFe2uafGrg CImfn2GRUDaJhyYZBpSa/pgNo7BCmCp3KqjrRYUs9az1hpxTHs7Qr7F3ig+v7OK9T4yO R0HWCLMAIgIdJENAgJWxdjjg37fk4w6u/GYSS4ttoTNQIbySC8Prdwbhw70IF5J+s5dI KxT+H0Z/MJYxfY47D0LywxmqBLBq2uPVckeWr/FMMOrxn9/MOAUgZWvl0b1jQQeNepmw sP7g== X-Gm-Message-State: APjAAAU20wMUaMv4VFp6BBuLL1VdJ5W4NvvbkaTgaBSBKSJLkEk3cIVD UqcE62eEUzBip5R0w7SBQuRWsmTpvpa43YVSkLY= X-Google-Smtp-Source: APXvYqx3j7zH+QaAUuEIZqF5KOX67+KACiYeFAz54D60MjqYLdvguyv/8mRyGFXbS5DW7jigB5BO9WpWi0BjLQzMaTc= X-Received: by 2002:a5d:8c89:: with SMTP id g9mr3170240ion.178.1581084666491; Fri, 07 Feb 2020 06:11:06 -0800 (PST) MIME-Version: 1.0 References: <1580980321-19256-1-git-send-email-harigovi@codeaurora.org> <2f5abc857910f70faa119fea5bda81d7@codeaurora.org> In-Reply-To: <2f5abc857910f70faa119fea5bda81d7@codeaurora.org> From: Jeffrey Hugo Date: Fri, 7 Feb 2020 07:10:55 -0700 Message-ID: Subject: Re: [Freedreno] [v1] drm/msm/dsi/pll: call vco set rate explicitly To: Harigovindan P Cc: "open list:DRM PANEL DRIVERS" , MSM , freedreno , DTML , lkml , Rob Clark , nganji@codeaurora.org, Sean Paul , kalyan_t@codeaurora.org, "Kristian H. Kristensen" Content-Type: text/plain; charset="UTF-8" Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Fri, Feb 7, 2020 at 5:38 AM wrote: > > On 2020-02-06 20:29, Jeffrey Hugo wrote: > > On Thu, Feb 6, 2020 at 2:13 AM Harigovindan P > > wrote: > >> > >> For a given byte clock, if VCO recalc value is exactly same as > >> vco set rate value, vco_set_rate does not get called assuming > >> VCO is already set to required value. But Due to GDSC toggle, > >> VCO values are erased in the HW. To make sure VCO is programmed > >> correctly, we forcefully call set_rate from vco_prepare. > > > > Is this specific to certain SoCs? I don't think I've observed this. > > As far as Qualcomm SOCs are concerned, since pll is analog and the value > is directly read from hardware if we get recalc value same as set rate > value, the vco_set_rate will not be invoked. We checked in our idp > device which has the same SOC but it works there since the rates are > different. This doesn't seem to be an answer to my question. What Qualcomm SoCs does this issue apply to? Everything implementing the 10nm pll? One specific SoC? I don't believe I've seen this on MSM8998, nor SDM845, so I'm interested to know what is the actual impact here. I don't see an "IDP" SoC in the IP catalog, so I really have no idea what you are referring to.