[RFC PATCH v1 1/1] mmc: zynq_sdhci: Only evaluate card-stable signal if card was detected

[Lukas Funke]

Hi Venkatesh,

On 30.05.2024 07:39, Abbarapu, Venkatesh wrote:
> Hi Lukas,
> The polling of card-stable bit alone is enough, as if card-detect bit is not set anyways the card-stable bit won't be set which leads to timeout.
> I don’t think it is specific to zynqmp platform.
> 
> Could you please let me know if you observe this issue on any of the zynqmp board?

We can observe this behaviour on zu2cg and zu3eg. I haven't tried it on 
an eval-board but this would be the next step.

The main problem is that the stable-bit is not set if there is no 
sd-card plugged in from the beginning, but only if the cd-signal changes.

Is there any documentation how this bit should behave then?

Best regards
- Lukas

> 
> Thanks
> Venkatesh
>> -----Original Message-----
>> From: Simek, Michal <michal.simek at amd.com>
>> Sent: Wednesday, May 29, 2024 8:33 PM
>> To: lukas.funke-oss at weidmueller.com; u-boot at lists.denx.de; Abbarapu,
>> Venkatesh <venkatesh.abbarapu at amd.com>
>> Cc: Stefan Herbrechtsmeier <Stefan.Herbrechtsmeier at weidmueller.com>;
>> Ashok Reddy Soma <ashok.reddy.soma at amd.com>; Lukas Funke
>> <lukas.funke at weidmueller.com>; Jaehoon Chung
>> <jh80.chung at samsung.com>; Johan Jonker <jbx6244 at gmail.com>; Peng Fan
>> <peng.fan at nxp.com>; Simon Glass <sjg at chromium.org>; Tom Rini
>> <trini at konsulko.com>
>> Subject: Re: [RFC PATCH v1 1/1] mmc: zynq_sdhci: Only evaluate card-stable
>> signal if card was detected
>>
>>
>>
>> On 4/24/24 10:23, lukas.funke-oss at weidmueller.com wrote:
>>> From: Lukas Funke <lukas.funke at weidmueller.com>
>>>
>>> On ZynqMp there seems to be a dependency between the card-stable bit
>>> and the card-detect bit. The card-stable bit is set *if and only if*
>>> the card-detect bit was set before, indicating that the signal was
>>> stable and reliable during card insertion.
>>>
>>> If the card-detect bit is *not* evaluated the corresponding check
>>> leads to a timeout indicating that the card-detect was not stable.
>>>
>>> Signed-off-by: Lukas Funke <lukas.funke at weidmueller.com>
>>> ---
>>>
>>>    drivers/mmc/zynq_sdhci.c | 7 +++++--
>>>    1 file changed, 5 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/mmc/zynq_sdhci.c b/drivers/mmc/zynq_sdhci.c index
>>> 935540d171..d0bccd41cc 100644
>>> --- a/drivers/mmc/zynq_sdhci.c
>>> +++ b/drivers/mmc/zynq_sdhci.c
>>> @@ -1168,11 +1168,14 @@ static int arasan_sdhci_probe(struct udevice
>> *dev)
>>>    	 */
>>>    	if (IS_ENABLED(CONFIG_ARCH_ZYNQMP) ||
>> IS_ENABLED(CONFIG_ARCH_VERSAL)) {
>>>    		u32 timeout = 1000000;
>>> +		u32 value;
>>>
>>> -		while (((sdhci_readl(host, SDHCI_PRESENT_STATE) &
>>> -			 SDHCI_CARD_STATE_STABLE) == 0) && timeout) {
>>> +		value = sdhci_readl(host, SDHCI_PRESENT_STATE);
>>> +		while ((value & SDHCI_CARD_PRESENT) &&
>>> +		       ((value & SDHCI_CARD_STATE_STABLE) == 0) && timeout)
>> {
>>>    			udelay(1);
>>>    			timeout--;
>>> +			value = sdhci_readl(host, SDHCI_PRESENT_STATE);
>>>    		}
>>>    		if (!timeout) {
>>>    			dev_err(dev, "Sdhci card detect state not stable\n");
>>
>> Venkatesh: Can you please take a look at this?
>>
>> Thanks,
>> Michal