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

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Message-ID: <CAOZ77oiV=2yFRNXgOD_ApEZGtd+LYK1oh+vrtaJZKr1g=EMBdQ@mail.gmail.com>
Date:	Thu, 18 Jun 2015 13:28:17 +0530
From:	Suneel G <suneelgarapati@...il.com>
To:	Dong Aisheng <b29396@...escale.com>
Cc:	Suneel Garapati <suneel.garapati@...inx.com>,
	linux-mmc@...r.kernel.org,
	"linux-kernel@...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>,
	Suman Tripathi <stripathi@....com>
Subject: Re: [PATCH] drivers: mmc: sdhci: update max frequency only if undefined

Hi,

On Thu, Jun 18, 2015 at 12:59 PM, Dong Aisheng <b29396@...escale.com> wrote:
> 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.

Ok, I missed your series.
My platform doesn't have clk_mul enabled hence couldn't check on that.
Agree on the sanity check.

Regards,
Suneel

>
> 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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