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Subject: Re: [PATCH V2 1/7] mmc: sdhci: add sd host v4 mode
To:     Chunyan Zhang <zhang.chunyan@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>
Cc:     linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
        Orson Zhai <orsonzhai@gmail.com>,
        Baolin Wang <baolin.wang@linaro.org>,
        Billows Wu <billows.wu@spreadtrum.com>, zhang.lyra@gmail.com
References: <1529028255-6022-1-git-send-email-zhang.chunyan@linaro.org>
 <1529028255-6022-2-git-send-email-zhang.chunyan@linaro.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: <1f3e7e87-be4e-37ab-af46-1c4e5dd79a1d@intel.com>
Date:   Thu, 21 Jun 2018 13:49:32 +0300
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On 15/06/18 05:04, Chunyan Zhang wrote:
> For SD host controller version 4.00 or later ones, there're two
> modes of implementation - Version 3.00 compatible mode or
> Version 4 mode.  This patch introduces a flag to record this.
> 
> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
> ---
>  drivers/mmc/host/sdhci.c | 6 ++++++
>  drivers/mmc/host/sdhci.h | 6 ++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 2ededa7f..cf5695f 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3302,6 +3302,12 @@ void __sdhci_read_caps(struct sdhci_host *host, u16 *ver, u32 *caps, u32 *caps1)
>  	v = ver ? *ver : sdhci_readw(host, SDHCI_HOST_VERSION);
>  	host->version = (v & SDHCI_SPEC_VER_MASK) >> SDHCI_SPEC_VER_SHIFT;
>  
> +	if (host->version >= SDHCI_SPEC_400) {
> +		if (sdhci_readw(host, SDHCI_HOST_CONTROL2) &
> +			SDHCI_CTRL_V4_MODE)
> +			host->v4_mode = true;
> +	}

At this point the host controller has just been reset which would mean it
must be in version 3 compatibility mode, which would mean this code doesn't
do anything.

> +
>  	if (host->quirks & SDHCI_QUIRK_MISSING_CAPS)
>  		return;
>  
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index c95b0a4..128b0ba 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -184,6 +184,7 @@
>  #define   SDHCI_CTRL_DRV_TYPE_D		0x0030
>  #define  SDHCI_CTRL_EXEC_TUNING		0x0040
>  #define  SDHCI_CTRL_TUNED_CLK		0x0080
> +#define  SDHCI_CTRL_V4_MODE		0x1000
>  #define  SDHCI_CTRL_PRESET_VAL_ENABLE	0x8000
>  
>  #define SDHCI_CAPABILITIES	0x40
> @@ -270,6 +271,8 @@
>  #define   SDHCI_SPEC_100	0
>  #define   SDHCI_SPEC_200	1
>  #define   SDHCI_SPEC_300	2
> +#define   SDHCI_SPEC_400	3
> +#define   SDHCI_SPEC_410	4
>  
>  /*
>   * End of controller registers.
> @@ -551,6 +554,9 @@ struct sdhci_host {
>  	u32			sdma_boundary;
>  
>  	unsigned long private[0] ____cacheline_aligned;
> +
> +	/* Host Version 4 Enable */
> +	bool			v4_mode;
>  };
>  
>  struct sdhci_ops {
>