[U-Boot] [PATCH] mmd: sdhci: fix non GPIO card detect

[Faiz Abbas]

Hi Baruch,

On 23/07/19 4:16 PM, Baruch Siach wrote:
> Hi Faiz,
> 
> On Tue, Jul 23, 2019 at 03:35:31PM +0530, Faiz Abbas wrote:
>> On 23/07/19 2:39 PM, Baruch Siach wrote:
>>> On Tue, Jul 23, 2019 at 02:27:28PM +0530, Faiz Abbas wrote:
>>>> On 23/07/19 1:30 PM, Peng Fan wrote:
>>>>> + Faiz
>>>>>
>>>>>> Subject: [PATCH] mmd: sdhci: fix non GPIO card detect
>>>>>>
>>>>>> Some SD cards do not assert the SDHCI_CARD_PRESENT bit. Only the
>>>>>> SDHCI_CARD_DETECT_PIN_LEVEL is enabled. Consider that enough for card
>>>>>> detect indication.
>>>>>>
>>>>>> This fixes SD card access from SPL, since DM_GPIO is not available in SPL
>>>>>> code.
>>>>>>
>>>>>> Fixes: da18c62b6e6a ("mmc: sdhci: Implement SDHCI card detect")
>>>>>> Cc: T Karthik Reddy <t.karthik.reddy at xilinx.com>
>>>>>> Cc: Michal Simek <michal.simek at xilinx.com>
>>>>>> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
>>>>>> ---
>>>>>>  drivers/mmc/sdhci.c | 2 +-
>>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c index
>>>>>> 2779bca93f08..17a28181fcca 100644
>>>>>> --- a/drivers/mmc/sdhci.c
>>>>>> +++ b/drivers/mmc/sdhci.c
>>>>>> @@ -683,7 +683,7 @@ int sdhci_get_cd(struct udevice *dev)
>>>>>>  	}
>>>>>>  #endif
>>>>>>  	value = !!(sdhci_readl(host, SDHCI_PRESENT_STATE) &
>>>>>> -		   SDHCI_CARD_PRESENT);
>>>>>> +		   (SDHCI_CARD_PRESENT | SDHCI_CARD_DETECT_PIN_LEVEL));
>>>>>
>>>>> Faiz, are you fine with this change?
>>>>
>>>> Not really. The spec is pretty clear that DETECT_PIN_LEVEL is not to be
>>>> trusted. Also how does the CARD_PRESENT assertion depend on the SD card
>>>> you use? Are you normally muxing the SDCD line to the IP (for hardware
>>>> to detect) or are you connecting it as a gpio which software must detect?
>>>
>>> I tested SanDisk 8GB SD card, class 10, UHS1, on Armada 388 based SolidRun 
>>> Clearfog Base. The SDHCI_PRESENT_STATE register consistently reads 0x01f60000, 
>>> that is, CARD_PRESENT is disabled, DETECT_PIN_LEVEL is enabled.
>>>
>>> The SD card-detect GPIO is present at the hardware level, but it is not 
>>> accessible from SPL code because there is currently no SPL_DM_GPIO. The main 
>>> U-Boot image detects the SD card correctly (once the other MMC patches I 
>>> posted are applied).
>>>
>>> Without this patch boot from SD card is broken. What is the right fix then?
>>
>> There are two choices to implement card detect:
>>
>> 1. Mux the card detect line from the SD card cage directly to the host
>> controller and expect PRESENT state register to indicate whether card is
>> present or not.
>>
>> 2. Mux the card detect line as a GPIO and use software
>> (dm_gpio_get_value() call) to detect whether card is present or not. In
>> that case, PRESENT_STATE[16,17,18] are completely useless because there
>> is no card detect line going into the IP.
>>
>> It seems that you are using #2. What confuses me is how any cards are
>> able to assert CARD_DETECT.
> 
> As far as I can see the Armada 388 SD host controller does not provide option 
> #1. The Clearfog indeed uses option #2. Until commit da18c62b6e6a4 ("mmc: 
> sdhci: Implement SDHCI card detect") it used to work because the mv_sdhci 
> driver does not implement the get_cd callback, so card-detect was ignored. Now 
> we have a get_cd implementation at the sdhci level that returns 0 in SPL 
> because the GPIO is not accessible.
> 
> What would you suggest?
> 

You can just add your own get_cd() callback instead of using sdhci_get_cd().

Thanks,
Faiz