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From:   Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Date:   Thu, 6 Feb 2020 07:59:52 -0700
Message-ID: <CAOCk7Nr9n-xLtWq=LEM-QFhJcY+QOuzazsoi-yjErA9od2Jwmw@mail.gmail.com>
Subject: Re: [Freedreno] [v1] drm/msm/dsi/pll: call vco set rate explicitly
To:     Harigovindan P <harigovi@codeaurora.org>
Cc:     "open list:DRM PANEL DRIVERS" <dri-devel@lists.freedesktop.org>,
        MSM <linux-arm-msm@vger.kernel.org>,
        freedreno <freedreno@lists.freedesktop.org>,
        DTML <devicetree@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Rob Clark <robdclark@gmail.com>, nganji@codeaurora.org,
        Sean Paul <seanpaul@chromium.org>, kalyan_t@codeaurora.org,
        "Kristian H. Kristensen" <hoegsberg@chromium.org>
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On Thu, Feb 6, 2020 at 2:13 AM Harigovindan P <harigovi@codeaurora.org> 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.