Re: [PATCH V2] mmc: sdhci-msm: Don't enable PWRSAVE_DLL for certain sdhc hosts

[Ulf Hansson]

On Fri, 7 Feb 2020 at 13:05, Veerabhadrarao Badiganti
<vbadigan@xxxxxxxxxxxxxx> wrote:
>
> From: Ritesh Harjani <riteshh@xxxxxxxxxxxxxx>
>
> SDHC core with new 14lpp and later tech DLL should not enable
> PWRSAVE_DLL since such controller's internal gating cannot meet
> following MCLK requirement:
> When MCLK is gated OFF, it is not gated for less than 0.5us and MCLK
> must be switched on for at-least 1us before DATA starts coming.
>
> Adding support for this requirement.
>
> Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxxx>
> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@xxxxxxxxxxxxxx>

Applied for next, thanks!

Kind regards
Uffe


> --
>
> Changes since V1:
>   Condition was not correct in V1, which is corrected in V2
>
> --
> ---
>  drivers/mmc/host/sdhci-msm.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index c3a160c..aa5b610 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -977,9 +977,21 @@ static int sdhci_msm_cm_dll_sdc4_calibration(struct sdhci_host *host)
>                 goto out;
>         }
>
> -       config = readl_relaxed(host->ioaddr + msm_offset->core_vendor_spec3);
> -       config |= CORE_PWRSAVE_DLL;
> -       writel_relaxed(config, host->ioaddr + msm_offset->core_vendor_spec3);
> +       /*
> +        * Set CORE_PWRSAVE_DLL bit in CORE_VENDOR_SPEC3.
> +        * When MCLK is gated OFF, it is not gated for less than 0.5us
> +        * and MCLK must be switched on for at-least 1us before DATA
> +        * starts coming. Controllers with 14lpp and later tech DLL cannot
> +        * guarantee above requirement. So PWRSAVE_DLL should not be
> +        * turned on for host controllers using this DLL.
> +        */
> +       if (!msm_host->use_14lpp_dll_reset) {
> +               config = readl_relaxed(host->ioaddr +
> +                               msm_offset->core_vendor_spec3);
> +               config |= CORE_PWRSAVE_DLL;
> +               writel_relaxed(config, host->ioaddr +
> +                               msm_offset->core_vendor_spec3);
> +       }
>
>         /*
>          * Drain writebuffer to ensure above DLL calibration
> --
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