RE: [PATCH v2] mmc: sdhci-of-esdhc: fixup PRESENT_STATE read

[Michael Walle <michael@walle.cc>]

Am 2016-11-14 04:00, schrieb Y.B. Lu:
>> -----Original Message-----
>> From: Michael Walle [mailto:michael@walle.cc]
>> Sent: Saturday, November 12, 2016 12:04 AM
>> To: linux-kernel@vger.kernel.org
>> Cc: linux-mmc@vger.kernel.org; Ulf Hansson; Adrian Hunter; yangbo lu;
>> Michael Walle
>> Subject: [PATCH v2] mmc: sdhci-of-esdhc: fixup PRESENT_STATE read
>> 
>> Since commit 87a18a6a5652 ("mmc: mmc: Use ->card_busy() to detect busy
>> cards in __mmc_switch()") the ESDHC driver is broken:
>>   mmc0: Card stuck in programming state! __mmc_switch
>>   mmc0: error -110 whilst initialising MMC card
>> 
>> Since this commit __mmc_switch() uses ->card_busy(), which is
>> sdhci_card_busy() for the esdhc driver. sdhci_card_busy() uses the
>> PRESENT_STATE register, specifically the DAT0 signal level bit. But 
>> the
>> ESDHC uses a non-conformant PRESENT_STATE register, thus a read fixup 
>> is
>> required to make the driver work again.
>> 
>> Signed-off-by: Michael Walle <michael@walle.cc>
>> Fixes: 87a18a6a5652 ("mmc: mmc: Use ->card_busy() to detect busy cards 
>> in
>> __mmc_switch()")
>> ---
>> v2:
>>  - use lower bits of the original value (that was actually a typo)
>>  - add fixes tag
>>  - fix typo
>> 
>>  drivers/mmc/host/sdhci-of-esdhc.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>> 
>> diff --git a/drivers/mmc/host/sdhci-of-esdhc.c 
>> b/drivers/mmc/host/sdhci-
>> of-esdhc.c
>> index fb71c86..f9c84bb 100644
>> --- a/drivers/mmc/host/sdhci-of-esdhc.c
>> +++ b/drivers/mmc/host/sdhci-of-esdhc.c
>> @@ -66,6 +66,18 @@ static u32 esdhc_readl_fixup(struct sdhci_host 
>> *host,
>>  			return ret;
>>  		}
>>  	}
>> +	/*
>> +	 * The DAT[3:0] line signal levels and the CMD line signal level is
>> +	 * not compatible with standard SDHC register. Move the
>> corresponding
>> +	 * bits around.
>> +	 */
>> +	if (spec_reg == SDHCI_PRESENT_STATE) {
>> +		ret = value & ~0xf8000000;
> 
> [Lu Yangbo-B47093] I think the bits which should be cleaned before
> following '|=' are 0x01f00000 not 0xf8000000, right?
> :)

Its neither 0x01f00000 nor 0xf8000000 :( I'll put the bits definition 
into the comment the next time, so everyone can review them. bit[31:24] 
are the line DAT[7:0] line signal level. bit[23] is command signal 
level. All other bits are the same as in the standard SDHC PRESENT_STATE 
register.

I want to keep all but the upper 9 bits from the original value, 
therefore, this should be the correct mask:
	ret = value & ~0xff800000;

-michael

> 
>> +		ret |= (value >> 4) & SDHCI_DATA_LVL_MASK;
>> +		ret |= (value << 1) & 0x01000000;
>> +		return ret;
>> +	}
>> +
>>  	ret = value;
>>  	return ret;
>>  }
>> --
>> 2.1.4