Re: [PATCH v10] mmc: support BKOPS feature for eMMC

[Adrian Hunter <adrian.hunter@intel.com>]

On 17/07/12 15:58, Jaehoon Chung wrote:
> On 07/17/2012 09:30 PM, Adrian Hunter wrote:
>> On 17/07/12 05:44, Jaehoon Chung wrote:
>>
>> <snip>
>>
>>> +/**
>>> + *	mmc_start_bkops - start BKOPS for supported cards
>>> + *	@card: MMC card to start BKOPS
>>> + *
>>> + *	Start background operations whenever requested.
>>> + *	when the urgent BKOPS bit is set in a R1 command response
>>> + *	then background operations should be started immediately.
>>> +*/
>>> +void mmc_start_bkops(struct mmc_card *card)
>>> +{
>>> +	int err;
>>> +	int timeout;
>>> +	u8 use_busy_signal;
>>> +
>>> +	BUG_ON(!card);
>>> +	if (!card->ext_csd.bkops_en || !(card->host->caps2 & MMC_CAP2_BKOPS))
>>> +		return;
>>> +
>>> +	if (mmc_is_exception_event(card, EXT_CSD_URGENT_BKOPS))
>>> +		if (card->ext_csd.raw_bkops_status)
>>> +			mmc_card_set_need_bkops(card);
>>> +
>>> +	/*
>>> +	 * If card is already doing bkops or need for
>>> +	 * bkops flag is not set, then do nothing just
>>> +	 * return
>>> +	 */
>>> +	if (mmc_card_doing_bkops(card) || !mmc_card_need_bkops(card))
>>> +		return;
>>> +
>>> +	mmc_claim_host(card->host);
>>> +	if (card->ext_csd.raw_bkops_status >= EXT_CSD_BKOPS_LEVEL_2) {
>>> +		timeout = MMC_BKOPS_MAX_TIMEOUT;
>>> +		use_busy_signal = 0;
>>> +	} else {
>>> +		timeout = 0;
>>> +		use_busy_signal = 1;
>>> +	}
>>
>> Is this the right way around?
> 
> use the mmc_switch() with R1B..
> this case is no problem, because after sending bkops, repeat the checking card status until prg-done.
> But, at sdhci controller, be occurred data timeout error.
> Because response type is r1b, and timeout value is too large.
> (Actually, i think that is controller's problem..but just its my test environment.)
> 
> if other sdhci controller working well with R1b, use_busy_signal need not.
> Just use the mmc_switch().
> 
> But When running bkops level2/3 use with R1 type, also no problem.
> Because the also checking status in mmc_switch() until prg-done.

You added:

+	/*
+	 * For urgent bkops status (LEVEL_2 and more)
+	 * bkops executed synchronously, otherwise
+	 * the operation is in progress
+	 */
+	if (card->ext_csd.raw_bkops_status < EXT_CSD_BKOPS_LEVEL_2)
+		mmc_card_set_doing_bkops(card);

But:
	status < 2		=> use_busy_signal = 1
	use_busy_signal = 1	=> waiting
	waiting			=> the operation is NOT in progress

Hence my question: Is this the right way around?

Also this change is needed for the addition of 'use_busy_signal' to
mmc_switch:

diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index baf90e0..e202a5e 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -417,7 +417,7 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
                err = mmc_send_status(card, &status);
                if (err)
                        return err;
-               if (card->host->caps & MMC_CAP_WAIT_WHILE_BUSY)
+               if (use_busy_signal && (card->host->caps & MMC_CAP_WAIT_WHILE_BUSY))
                        break;
                if (mmc_host_is_spi(card->host))
                        break;