[U-Boot] [PATCH] mmc: implement SDHCI card detect

[Michal Simek]

On 31. 05. 19 15:27, Ibai Erkiaga Elorza wrote:
> Hi Michal,
> 
>> -----Original Message-----
>> From: Michal Simek <michal.simek at xilinx.com>
>> Sent: 27 May 2019 06:53
>> To: Ibai Erkiaga Elorza <IBAIE at xilinx.com>; u-boot at lists.denx.de
>> Subject: Re: [U-Boot] [PATCH] mmc: implement SDHCI card detect
>>
>> On 23. 05. 19 15:54, Ibai Erkiaga wrote:
>>> Card detect function implemented for SDHCI framework.
>>>
>>> Signed-off-by: Ibai Erkiaga <ibai.erkiaga-elorza at xilinx.com>
>>> ---
>>>
>>>  drivers/mmc/sdhci.c | 17 +++++++++++++++++
>>>  1 file changed, 17 insertions(+)
>>>
>>> diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c index
>>> e2bb90a..cb4db8d 100644
>>> --- a/drivers/mmc/sdhci.c
>>> +++ b/drivers/mmc/sdhci.c
>>> @@ -390,6 +390,21 @@ static int sdhci_send_command(struct mmc *mmc,
>> struct mmc_cmd *cmd,
>>>  		return -ECOMM;
>>>  }
>>>
>>> +#if IS_ENABLED(CONFIG_DM_MMC)
>>> +static int sdhci_get_cd(struct udevice *dev) {
>>> +	struct mmc *mmc = mmc_get_mmc_dev(dev); #else static int
>>> +sdhci_get_cd(struct mmc *mmc) { #endif
>>> +	u32 state;
>>> +	struct sdhci_host *host = mmc->priv;
>>> +
>>> +	state = sdhci_readl(host, SDHCI_PRESENT_STATE);
>>> +	return (state & SDHCI_CARD_PRESENT);
>>
>> This should be much more robust. It should at least handle cases where you
>> have broken-cd, cd-gpios, cd-inverted cases.
>> This code will likely work with boards which have CD connected properly but
>> it is enabled for all which will cause a lot of issues.
>>
> You are right, this implementation is quite basic and the idea was just to get rid-off the polling message for the golden use case (properly connected CD).
> 
>> If you want to add this functionality one by one then new Kconfig should be
>> used but I am not big fan of that.
>>
> The broken-cd Kconfig is already in the MMC framework so I would say that you can use this implementation if your CD is properly connected and just stay as current implementation using CONFIG_MMC_BROKEN_CD.


I expect that there are several pieces around but it needs to be done
properly or this will break a lot of boards.

M