linux-kernel - Re: [PATCH 2/2] mmc: dw_mmc: Give a good reset after we give power

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Message-id: <54EDA58C.7050605@samsung.com>
Date:	Wed, 25 Feb 2015 19:35:56 +0900
From:	Jaehoon Chung <jh80.chung@...sung.com>
To:	Doug Anderson <dianders@...omium.org>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Alim Akhtar <alim.akhtar@...sung.com>,
	Sonny Rao <sonnyrao@...omium.org>,
	Andrew Bresticker <abrestic@...omium.org>,
	Heiko Stuebner <heiko@...ech.de>,
	Addy Ke <addy.ke@...k-chips.com>,
	Alexandru Stan <amstan@...omium.org>,
	javier.martinez@...labora.co.uk, chris@...ntf.net,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mmc: dw_mmc: Give a good reset after we give power

Dear, Doug.

Looks good to me. Thanks!

Acked-by: Jaehoon Chung <jh80.chung@...sung.com>

Best Regards,
Jaehoon Chung

On 02/21/2015 03:57 AM, Doug Anderson wrote:
> We should give dw_mmc a good reset after we apply power.  On some
> boards vqmmc may actually be connected to the IP block in the SoC so
> it's good to reset after power comes in.
> 
> Without this we sometimes see failures enumerating cards on rk3288.
> 
> Signed-off-by: Doug Anderson <dianders@...omium.org>
> ---
>  drivers/mmc/host/dw_mmc.c | 27 ++++++++++++++++++---------
>  1 file changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 43fcae1..6a712ae 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -1119,13 +1119,23 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  		mci_writel(slot->host, PWREN, regs);
>  		break;
>  	case MMC_POWER_ON:
> -		if (!IS_ERR(mmc->supply.vqmmc) && !slot->host->vqmmc_enabled) {
> -			ret = regulator_enable(mmc->supply.vqmmc);
> -			if (ret < 0)
> -				dev_err(slot->host->dev,
> -					"failed to enable vqmmc regulator\n");
> -			else
> +		if (!slot->host->vqmmc_enabled) {
> +			if (!IS_ERR(mmc->supply.vqmmc)) {
> +				ret = regulator_enable(mmc->supply.vqmmc);
> +				if (ret < 0)
> +					dev_err(slot->host->dev,
> +						"failed to enable vqmmc\n");
> +				else
> +					slot->host->vqmmc_enabled = true;
> +
> +			} else {
> +				/* Keep track so we don't reset again */
>  				slot->host->vqmmc_enabled = true;
> +			}
> +
> +			/* Reset our state machine after powering on */
> +			dw_mci_ctrl_reset(slot->host,
> +					  SDMMC_CTRL_ALL_RESET_FLAGS);
>  		}
>  
>  		/* Adjust clock / bus width after power is up */
> @@ -1139,10 +1149,9 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>  		if (!IS_ERR(mmc->supply.vmmc))
>  			mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
>  
> -		if (!IS_ERR(mmc->supply.vqmmc) && slot->host->vqmmc_enabled) {
> +		if (!IS_ERR(mmc->supply.vqmmc) && slot->host->vqmmc_enabled)
>  			regulator_disable(mmc->supply.vqmmc);
> -			slot->host->vqmmc_enabled = false;
> -		}
> +		slot->host->vqmmc_enabled = false;
>  
>  		regs = mci_readl(slot->host, PWREN);
>  		regs &= ~(1 << slot->id);
> 

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