linux-kernel - Re: [PATCH]mmc: set timeout for SDHCI host before sending busy cmds

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Message-id: <4D7D58D8.6070402@samsung.com>
Date:	Mon, 14 Mar 2011 08:52:56 +0900
From:	Jaehoon Chung <jh80.chung@...sung.com>
To:	Philip Rakity <prakity@...vell.com>
Cc:	Jaehoon Chung <jh80.chung@...sung.com>,
	Chuanxiao Dong <chuanxiao.dong@...el.com>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"cjb@...top.org" <cjb@...top.org>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	"w.sang@...gutronix.de" <w.sang@...gutronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH]mmc: set timeout for SDHCI host before sending busy cmds

Philip Rakity wrote:
> On Mar 9, 2011, at 6:29 PM, Jaehoon Chung wrote:
> 
>> Chuanxiao Dong wrote:
>>> Hi all,
>>>   From the previous discussion, I do not think we have got a clear conclusion
>>>   about using maximum timeout value. At least we know from Jae hoon Chung
>>>   using 0xE for every case is not a good. So I want to suggest only use 0xE for
>>>   busy command. I personally preferred below implementation, which is similar
>>>   with a RFC patch submitted by Jae hoon Chung, but only without adding a new
>>>   quirk.
>> thanks for remind. 
>> Yes, i tested without quirks, i think that is not problem.
>> (Just sent RFC patch with quirks, because i want to ask how think about adding quirks or not).
> 
> 
> 
> Sorry I am confused.
> 
> Setting 0x0E all the time does not solve the problem and has side effects ?
> What are the side effects ?

Side effect?? i didn't mention "side effect", just not resolved for every case..
That case is SDHCI didn't support the specific cards during suspend/resume.

i didn't know Mr.Chuanxiao's case.

> 
> Using BUSY patch for 0x0e (below) works ?
> 
>>>   I think sdhci_calc_timeout should be left for data transfer since at least we
>>>   can get a warning if 0xE is not enough for host to use. And if the host
>>>   controller and the card have no bugs, then the calculated timeout should be
>>>   safe. Left the old implementation unchanged is also compatible with all
>>>   existed host controllers and cards.
>>>
>>>   But for busy command, we are not clear about how long is safe enough for
>>>   waiting and there is also no function to do the calculation for them. So
>>>   preferred just using 0xE. Below the patch and comment:
>>>
>>> Set the timeout control register for SDHCI host when send some commands which
>>> need busy signal. Use the maximum timeout value 0xE will be safe.
>>>
>>> Signed-off-by: Chuanxiao Dong <chuanxiao.dong@...el.com>
>>> ---
>>> drivers/mmc/host/sdhci.c |    9 ++++++++-
>>> 1 files changed, 8 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index 99c372e..8306323 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -659,8 +659,15 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
>>>
>>> 	WARN_ON(host->data);
>>>
>>> -	if (data == NULL)
>>> +	if (data == NULL) {
>>> +		/*
>>> +		 * set the timeout to be maximum value for commands those with
>>> +		 * busy signal
>>> +		 */
>>> +		if (host->cmd->flags & MMC_RSP_BUSY)
>>> +			sdhci_writeb(host, 0xE, SDHCI_TIMEOUT_CONTROL);
>>> 		return;
>>> +	}
>>>
>>> 	/* Sanity checks */
>>> 	BUG_ON(data->blksz * data->blocks > 524288);
> 
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