linux-kernel - Re: [PATCH] mmc: sdhci-pci-gli: Finetune GL9763E L1 Entry Delay

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Date:   Wed, 30 Jun 2021 17:15:31 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Renius Chen <reniuschengl@...il.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ben Chuang <Ben.Chuang@...esyslogic.com.tw>
Subject: Re: [PATCH] mmc: sdhci-pci-gli: Finetune GL9763E L1 Entry Delay

On Thu, 24 Jun 2021 at 04:56, Renius Chen <reniuschengl@...il.com> wrote:
>
> Finetune the L1 entry delay to 20us for better balance of performance and
> battery life.
>
> Signed-off-by: Renius Chen <reniuschengl@...il.com>
> ---
>  drivers/mmc/host/sdhci-pci-gli.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
> index 302a7579a9b3..4e3c0561354d 100644
> --- a/drivers/mmc/host/sdhci-pci-gli.c
> +++ b/drivers/mmc/host/sdhci-pci-gli.c
> @@ -90,7 +90,7 @@
>
>  #define PCIE_GLI_9763E_CFG2      0x8A4
>  #define   GLI_9763E_CFG2_L1DLY     GENMASK(28, 19)
> -#define   GLI_9763E_CFG2_L1DLY_MID 0x54
> +#define   GLI_9763E_CFG2_L1DLY_MID 0x50

We just changed from 21us to 20us. Really, how big of a difference can
this make?

Moreover, I suppose the difference is related to the running use case. No?

If you really want this, at least I want an ack from Ben for it, then
let's be done with it.

Kind regards
Uffe

>
>  #define PCIE_GLI_9763E_MMC_CTRL  0x960
>  #define   GLI_9763E_HS400_SLOW     BIT(3)
> @@ -810,7 +810,7 @@ static void gli_set_gl9763e(struct sdhci_pci_slot *slot)
>
>         pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG2, &value);
>         value &= ~GLI_9763E_CFG2_L1DLY;
> -       /* set ASPM L1 entry delay to 21us */
> +       /* set ASPM L1 entry delay to 20us */
>         value |= FIELD_PREP(GLI_9763E_CFG2_L1DLY, GLI_9763E_CFG2_L1DLY_MID);
>         pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG2, value);
>
> --
> 2.27.0
>