linux-kernel - Re: [PATCH] mmc: dw_mmc: Don't print data errors

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Date:	Wed, 23 Apr 2014 09:43:21 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Ulf Hansson <ulf.hansson@...aro.org>,
	Seungwon Jeon <tgih.jun@...sung.com>
Cc:	Jaehoon Chung <jh80.chung@...sung.com>,
	Yuvaraj Kumar C D <yuvaraj.cd@...sung.com>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	Sonny Rao <sonnyrao@...omium.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Chris Ball <chris@...ntf.net>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: dw_mmc: Don't print data errors

Seungwon / Ulf,

On Wed, Apr 23, 2014 at 1:17 AM, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> On 23 April 2014 01:51, Doug Anderson <dianders@...omium.org> wrote:
>> Data errors are completely expected during tuning.  Printing them out
>> is confusing people looking at the kernel logs.  They see things like:
>>
>>  [    3.613296] dwmmc_exynos 12200000.dwmmc0: data error, status 0x00000088
>>
>> ...and they think something is wrong with their hardware.
>>
>> Remove the printouts.  We'll leave it up to a higher level to report
>> about errors.
>>
>> Signed-off-by: Doug Anderson <dianders@...omium.org>
>> ---
>>  drivers/mmc/host/dw_mmc.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index cced599..4c8d423 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -1248,7 +1248,7 @@ static int dw_mci_data_complete(struct dw_mci *host, struct mmc_data *data)
>>                         data->error = -EIO;
>>                 }
>>
>> -               dev_err(host->dev, "data error, status 0x%08x\n", status);
>> +               dev_dbg(host->dev, "data error, status 0x%08x\n", status);
>>
>
> The "status" here could be useful information about the status
> register, which is not considered while printing errors by the "higher
> levels". An option could be to print the error, but not when you
> perform tuning.
>
> No big deal though, just a thought.

Right, I could potentially put the driver into "tuning" mode and then
suppress the errors during that time.  If you request it I will do
that.

I will also note that there are many other error conditions in the
driver that don't have such printouts.  I think the general philosophy
of this driver is not to print them...

-Doug
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