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Subject: Re: [PATCH V2] mmc: sdhci-msm: Don't enable PWRSAVE_DLL for certain
 sdhc hosts
To:     Veerabhadrarao Badiganti <vbadigan@codeaurora.org>,
        ulf.hansson@linaro.org
Cc:     asutoshd@codeaurora.org, stummala@codeaurora.org,
        sayalil@codeaurora.org, cang@codeaurora.org,
        rampraka@codeaurora.org, linux-mmc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        Ritesh Harjani <riteshh@codeaurora.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>
References: <1581062518-11655-1-git-send-email-vbadigan@codeaurora.org>
 <1581077075-26011-1-git-send-email-vbadigan@codeaurora.org>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <64ca4304-faab-cc82-0c7b-24a7f504bbd7@intel.com>
Date:   Tue, 18 Feb 2020 09:11:18 +0200
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On 7/02/20 2:04 pm, Veerabhadrarao Badiganti wrote:
> From: Ritesh Harjani <riteshh@codeaurora.org>
> 
> 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@codeaurora.org>
> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> --
> 
> 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
>