linux-kernel - Re: [PATCH v3 5/6] mmc: sdhci-esdhc-imx: config watermark level and burst length

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Message-ID: <20150731145140.GE27806@shlinux1.ap.freescale.net>
Date:	Fri, 31 Jul 2015 22:51:41 +0800
From:	Dong Aisheng <aisheng.dong@...escale.com>
To:	Haibo Chen <haibo.chen@...escale.com>
CC:	<robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
	<shawnguo@...nel.org>, <kernel@...gutronix.de>,
	<linux@....linux.org.uk>, <ulf.hansson@...aro.org>,
	<johan.derycke@...co.com>, <fabio.estevam@...escale.com>,
	<b29396@...escale.com>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH v3 5/6] mmc: sdhci-esdhc-imx: config watermark level
 and burst length

On Wed, Jul 29, 2015 at 05:03:56PM +0800, Haibo Chen wrote:
> i.MX7D support eMMC HS400 mode, this mode can run in 8 bit,200MHZ
> DDR mode. So the I/O speed improve a lot compare to SD3.0
> 
> The default burst length is 8, if we don't change this value, in
> HS400 mode, when we do eMMC read operation, we can find that the
> clock signal will stop for a period of time. This means the speed
> of data moving on AHB bus is slower than I/O speed. So we should
> improve the speed of data moving on AHB bus.
> 
> For imx7d usdhc, this patch set the burst length as 16, and set
> watermark level as 64. The test result is the clock signal has
> no stop during the eMMC HS400 operation. For other imx usdhc, remain
> the default value: burst length as 8, watermark level as 16.
> 
> Signed-off-by: Haibo Chen <haibo.chen@...escale.com>
> ---
>  drivers/mmc/host/sdhci-esdhc-imx.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
> index 158f93b..37d0095 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -239,6 +239,11 @@ static inline int is_imx6q_usdhc(struct pltfm_imx_data *data)
>  	return data->socdata == &usdhc_imx6q_data;
>  }
>  
> +static inline int is_imx7d_usdhc(struct pltfm_imx_data *data)
> +{
> +	return data->socdata == &usdhc_imx7d_data;
> +}

Can we using flag to check instead of adding more is_imx_usdhc()?

> +
>  static inline int esdhc_is_usdhc(struct pltfm_imx_data *data)
>  {
>  	return !!(data->socdata->flags & ESDHC_FLAG_USDHC);
> @@ -1145,7 +1150,11 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
>  	 * to something insane.  Change it back here.
>  	 */
>  	if (esdhc_is_usdhc(imx_data)) {
> -		writel(0x08100810, host->ioaddr + ESDHC_WTMK_LVL);
> +		if (is_imx7d_usdhc(imx_data))
> +			writel(0x10401040, host->ioaddr + ESDHC_WTMK_LVL);
> +		else
> +			writel(0x08100810, host->ioaddr + ESDHC_WTMK_LVL);
> +
>  		host->quirks2 |= SDHCI_QUIRK2_PRESET_VALUE_BROKEN;
>  		host->mmc->caps |= MMC_CAP_1_8V_DDR;
>  

Regards
Dong Aisheng

> -- 
> 1.9.1
> 
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