linux-kernel - Re: [PATCH] drivers: mmc: sdhci: update max frequency only if undefined

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Date:	Thu, 18 Jun 2015 15:29:41 +0800
From:	Dong Aisheng <b29396@...escale.com>
To:	Suneel Garapati <suneel.garapati@...inx.com>
CC:	<linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Ulf Hansson <ulf.hansson@...aro.org>, <michals@...inx.com>,
	<sorenb@...inx.com>, "Adrian Hunter" <adrian.hunter@...el.com>,
	Haibo Chen <haibo.chen@...escale.com>,
	Tim Kryger <tim.kryger@...il.com>,
	Shawn Guo <shawn.guo@...aro.org>, Yi Sun <yi.y.sun@...el.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	<stripathi@....com>
Subject: Re: [PATCH] drivers: mmc: sdhci: update max frequency only if
 undefined

On Thu, Jun 18, 2015 at 12:57:07PM +0530, Suneel Garapati wrote:
> f_max parameter of mmc structure is updated unconditionally.
> If dt property max-frequency is assigned, this update is
> overwriting the dt property value which is undesired.
> 
> Signed-off-by: Suneel Garapati <suneel.garapati@...inx.com>
> ---
>  drivers/mmc/host/sdhci.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index bc14452..c2917d5 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3047,7 +3047,10 @@ int sdhci_add_host(struct sdhci_host *host)
> 	 * Set host parameters.
> 	 */
> 	mmc->ops = &sdhci_ops;
> -	mmc->f_max = host->max_clk;
> +
> +	if(!mmc->f_max)
> +		mmc->f_max = host->max_clk;
> +

This is probably not going to work properly.
mmc->f_max will be overwritten again if host->clk_mul enabled.
And you did not do sanity check if f_max from device tree is valid.

Please see:
http://www.spinics.net/lists/arm-kernel/msg426167.html
I already sent a proper fix.

Regards
Dong Aisheng

> 	if (host->ops->get_min_clock)
> 		mmc->f_min = host->ops->get_min_clock(host);
> 	else if (host->version >= SDHCI_SPEC_300) {
> --
> 2.1.2
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