linux-kernel - Re: [PATCH 2/2] mmc: sdhci-msm: Re-initialize DLL if MCLK is gated dynamically

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Message-ID: <CAD=FV=VxLR6v3vyimjznrqa1Tj5rPziPQX7Pt+wJRR+xm1N-0A@mail.gmail.com>
Date:   Tue, 25 Sep 2018 15:28:15 -0700
From:   Doug Anderson <dianders@...gle.com>
To:     vbadigan@...eaurora.org
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Asutosh Das <asutoshd@...eaurora.org>, riteshh@...eaurora.org,
        stummala@...eaurora.org, sayalil@...eaurora.org,
        Evan Green <evgreen@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] mmc: sdhci-msm: Re-initialize DLL if MCLK is gated dynamically

Hi,

On Tue, Sep 25, 2018 at 8:05 AM Veerabhadrarao Badiganti
<vbadigan@...eaurora.org> wrote:
> +       /*
> +        * Whenever core-clock is gated dynamically, it's needed to
> +        * re-initialize the DLL when the clock is ungated.
> +        */
> +       if (msm_host->restore_dll_cfg_needed && msm_host->clk_rate) {
> +               msm_host->restore_dll_cfg = true;
> +               mmc_retune_needed(host->mmc);

Using the boolean "restore_dll_cfg" to communicate like this seems
really fragile.  I have no basis in fact, but I worry that something
will happen in the meantime that really ought to invalidate the
"saved_tuning_phase" but the boolean will still be set.

Is there a reason you can't just call msm_config_cm_dll_phase()
directly from sdhci_msm_runtime_resume()?  Perhaps after the
clk_bulk_prepare_enable() call below?


-Doug