linux-kernel - Re: [PATCH v2] mmc: sdhci-pci-gli: Disable LPM during initialization

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Message-ID: <CAG-rBig6XHoPSch5OqO_yNrYsX2szkyce0K==xqmrJXKT-2Jgg@mail.gmail.com>
Date:   Tue, 14 Nov 2023 08:01:58 -0500
From:   Sven van Ashbrook <svenva@...omium.org>
To:     Kornel Dulęba <korneld@...omium.org>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Jason Lai <jasonlai.genesyslogic@...il.com>,
        Victor Shih <victor.shih@...esyslogic.com.tw>,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>,
        Stanisław Kardach <skardach@...gle.com>,
        linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] mmc: sdhci-pci-gli: Disable LPM during initialization

LGTM.
Reviewed-by: Sven van Ashbrook <svenva@...omium.org>

On Tue, Nov 14, 2023 at 6:56 AM Kornel Dulęba <korneld@...omium.org> wrote:
>
> To address IO performance commit f9e5b33934ce
> ("mmc: host: Improve I/O read/write performance for GL9763E")
> limited LPM negotiation to runtime suspend state.
> The problem is that it only flips the switch in the runtime PM
> resume/suspend logic.
>
> Disable LPM negotiation in gl9763e_add_host.
> This helps in two ways:
> 1. It was found that the LPM switch stays in the same position after
>    warm reboot. Having it set in init helps with consistency.
> 2. Disabling LPM during the first runtime resume leaves us susceptible
>    to the performance issue in the time window between boot and the
>    first runtime suspend.
>
> Fixes: f9e5b33934ce ("mmc: host: Improve I/O read/write performance for GL9763E")
> Cc: stable@...r.kernel.org
> Signed-off-by: Kornel Dulęba <korneld@...omium.org>
> ---
> v2: Move up gl9763e_set_low_power_negotiation to avoid having to forward
>     declare it.
>
>  drivers/mmc/host/sdhci-pci-gli.c | 54 +++++++++++++++++---------------
>  1 file changed, 29 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
> index d8a991b349a8..77911a57b12c 100644
> --- a/drivers/mmc/host/sdhci-pci-gli.c
> +++ b/drivers/mmc/host/sdhci-pci-gli.c
> @@ -1189,6 +1189,32 @@ static void gl9763e_hs400_enhanced_strobe(struct mmc_host *mmc,
>         sdhci_writel(host, val, SDHCI_GLI_9763E_HS400_ES_REG);
>  }
>
> +static void gl9763e_set_low_power_negotiation(struct sdhci_pci_slot *slot,
> +                                             bool enable)
> +{
> +       struct pci_dev *pdev = slot->chip->pdev;
> +       u32 value;
> +
> +       pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +       value &= ~GLI_9763E_VHS_REV;
> +       value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_W);
> +       pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +
> +       pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG, &value);
> +
> +       if (enable)
> +               value &= ~GLI_9763E_CFG_LPSN_DIS;
> +       else
> +               value |= GLI_9763E_CFG_LPSN_DIS;
> +
> +       pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG, value);
> +
> +       pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +       value &= ~GLI_9763E_VHS_REV;
> +       value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_R);
> +       pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +}
> +
>  static void sdhci_set_gl9763e_signaling(struct sdhci_host *host,
>                                         unsigned int timing)
>  {
> @@ -1297,6 +1323,9 @@ static int gl9763e_add_host(struct sdhci_pci_slot *slot)
>         if (ret)
>                 goto cleanup;
>
> +       /* Disable LPM negotiation to avoid entering L1 state. */
> +       gl9763e_set_low_power_negotiation(slot, false);
> +
>         return 0;
>
>  cleanup:
> @@ -1340,31 +1369,6 @@ static void gli_set_gl9763e(struct sdhci_pci_slot *slot)
>  }
>
>  #ifdef CONFIG_PM
> -static void gl9763e_set_low_power_negotiation(struct sdhci_pci_slot *slot, bool enable)
> -{
> -       struct pci_dev *pdev = slot->chip->pdev;
> -       u32 value;
> -
> -       pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> -       value &= ~GLI_9763E_VHS_REV;
> -       value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_W);
> -       pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> -
> -       pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG, &value);
> -
> -       if (enable)
> -               value &= ~GLI_9763E_CFG_LPSN_DIS;
> -       else
> -               value |= GLI_9763E_CFG_LPSN_DIS;
> -
> -       pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG, value);
> -
> -       pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> -       value &= ~GLI_9763E_VHS_REV;
> -       value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_R);
> -       pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> -}
> -
>  static int gl9763e_runtime_suspend(struct sdhci_pci_chip *chip)
>  {
>         struct sdhci_pci_slot *slot = chip->slots[0];
> --
> 2.43.0.rc0.421.g78406f8d94-goog
>