linux-kernel - Re: [PATCH v3] mmc: Make ID freq configurable

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Date:	Fri, 27 Aug 2010 21:44:15 +0100
From:	Chris Ball <cjb@...top.org>
To:	Hein_Tibosch <hein_tibosch@...oo.es>
Cc:	Pierre Ossman <pierre@...man.eu>, Ben Nizette <bn@...sdigital.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Adrian Hunter <adrian.hunter@...ia.com>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Matt Fleming <matt@...sole-pimps.org>,
	akpm@...ux-foundation.org
Subject: Re: [PATCH v3] mmc: Make ID freq configurable

Hi,

This looks like the best of the min_freq patches I've seen, and is
implementing a suggestion of Pierre's.  Should we take it?

- Chris.

On Tue, Jan 05, 2010 at 05:58:34AM +0800, Hein_Tibosch wrote:
> 
> In my last mail the spaces in the patch were mistreated, sorry for that.
> 
> Below a patch which tries mmc-initialization using several frequencies
> from an array 400, 300, 200 and 100.
> 
> 
> Signed-off-by: Hein Tibosch <hein_tibosch@...oo.es>
> 
> ---
> diff -Nurp a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -891,12 +891,7 @@ static void mmc_power_up(struct mmc_host
>  	 */
>  	mmc_delay(10);
> 
> -	if (host->f_min > 400000) {
> -		pr_warning("%s: Minimum clock frequency too high for "
> -				"identification mode\n", mmc_hostname(host));
> -		host->ios.clock = host->f_min;
> -	} else
> -		host->ios.clock = 400000;
> +	host->ios.clock = host->f_init;
> 
>  	host->ios.power_mode = MMC_POWER_ON;
>  	mmc_set_ios(host);
> @@ -1041,6 +1036,8 @@ void mmc_rescan(struct work_struct *work
>  		container_of(work, struct mmc_host, detect.work);
>  	u32 ocr;
>  	int err;
> +	int i;
> +	unsigned freqs[] = { 400000, 300000, 200000, 100000 };
> 
>  	mmc_bus_get(host);
> 
> @@ -1070,46 +1067,55 @@ void mmc_rescan(struct work_struct *work
>  	if (host->ops->get_cd && host->ops->get_cd(host) == 0)
>  		goto out;
> 
> -	mmc_claim_host(host);
> +	for (i = 0; i < ARRAY_SIZE(freqs); i++) {
> +		mmc_claim_host(host);
> 
> -	mmc_power_up(host);
> -	mmc_go_idle(host);
> +		if (freqs[i] >= host->f_min)
> +			host->f_init = freqs[i];
> +		else if (i && freqs[i-1] <= host->f_min)
> +			goto out;
> +		else
> +			host->f_init = host->f_min;
> 
> -	mmc_send_if_cond(host, host->ocr_avail);
> +		printk ("mmc_rescan: trying %u Hz\n", host->f_init);
> +		mmc_power_up(host);
> +		mmc_go_idle(host);
> 
> -	/*
> -	 * First we search for SDIO...
> -	 */
> -	err = mmc_send_io_op_cond(host, 0, &ocr);
> -	if (!err) {
> -		if (mmc_attach_sdio(host, ocr))
> -			mmc_power_off(host);
> -		goto out;
> -	}
> +		mmc_send_if_cond(host, host->ocr_avail);
> 
> -	/*
> -	 * ...then normal SD...
> -	 */
> -	err = mmc_send_app_op_cond(host, 0, &ocr);
> -	if (!err) {
> -		if (mmc_attach_sd(host, ocr))
> -			mmc_power_off(host);
> -		goto out;
> -	}
> +		/*
> +		 * First we search for SDIO...
> +		 */
> +		err = mmc_send_io_op_cond(host, 0, &ocr);
> +		if (!err) {
> +			if (mmc_attach_sdio(host, ocr))
> +				mmc_power_off(host);
> +			goto out;
> +		}
> 
> -	/*
> -	 * ...and finally MMC.
> -	 */
> -	err = mmc_send_op_cond(host, 0, &ocr);
> -	if (!err) {
> -		if (mmc_attach_mmc(host, ocr))
> -			mmc_power_off(host);
> -		goto out;
> -	}
> +		/*
> +		 * ...then normal SD...
> +		 */
> +		err = mmc_send_app_op_cond(host, 0, &ocr);
> +		if (!err) {
> +			if (mmc_attach_sd(host, ocr))
> +				mmc_power_off(host);
> +			goto out;
> +		}
> 
> -	mmc_release_host(host);
> -	mmc_power_off(host);
> +		/*
> +		 * ...and finally MMC.
> +		 */
> +		err = mmc_send_op_cond(host, 0, &ocr);
> +		if (!err) {
> +			if (mmc_attach_mmc(host, ocr))
> +				mmc_power_off(host);
> +			goto out;
> +		}
> 
> +		mmc_release_host(host);
> +		mmc_power_off(host);
> +	}
>  out:
>  	if (host->caps & MMC_CAP_NEEDS_POLL)
>  		mmc_schedule_delayed_work(&host->detect, HZ);
> diff -Nurp a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -119,6 +119,7 @@ struct mmc_host {
>  	const struct mmc_host_ops *ops;
>  	unsigned int		f_min;
>  	unsigned int		f_max;
> +	unsigned int		f_init;
>  	u32			ocr_avail;
> 
>  #define MMC_VDD_165_195		0x00000080	/* VDD voltage 1.65 - 1.95 */
> 
> 
> --

-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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