Re: [Question] What does SDHCI_QUIRK_BROKEN_CARD_DETECTION stands for?

Re: [Question] What does SDHCI_QUIRK_BROKEN_CARD_DETECTION stands for?

[Kevin Liu]

2013/2/27 Chris Ball <cjb@laptop.org>:
> Hi,
>
> The CC: list seems excessively long here.
>
> On Wed, Feb 27 2013, Kevin Liu wrote:
>> Who can help to answer below question?
>> Which statement is true if quirk SDHCI_QUIRK_BROKEN_CARD_DETECTION is selected?
>> 1. The host controller Present State Register[18] (offset 0x24) can
>> reflect card status (present or not) but can't trigger interrupt when
>> card insert/remove.
>> 2. The host controller Present State Register[18] can't reflect card
>> status at all and can't trigger card insert/remove interrupt either.
>> But have other way out of host controller to detect card like slot
>> gpio.
>> 3. The host controller Present State Register[18] can't reflect card
>> status at all, can't trigger card insert/remove interrupt, and don't
>> have the other ways to detect card like slot gpio. So have to use
>> polling to know card present status.
>
> (3)
>
> The best documentation for this is probably the DT bindings file:
>
> Card detection:
> If no property below is supplied, host native card detect is used.
> Only one of the properties in this section should be supplied:
>   - broken-cd: There is no card detection available; polling must be used.
>   - cd-gpios: Specify GPIOs for card detection, see gpio binding
>   - non-removable: non-removable slot (like eMMC); assume always present.
>
> (SDHCI_QUIRK_BROKEN_CARD_DETECTION maps to broken-cd)
>
Chris,

Thanks for quick answer!
Then if broken-cd/SDHCI_QUIRK_BROKEN_CARD_DETECTION is selected, can I
use host controller Present State Register[18] (offset 0x24) to know
card status (present or not)?

Kevin

> - Chris.
> --
> Chris Ball   <cjb@laptop.org>   <http://printf.net/>
> One Laptop Per Child

Re: [Question] What does SDHCI_QUIRK_BROKEN_CARD_DETECTION stands for?

[Chris Ball]

Hi,

On Wed, Feb 27 2013, Kevin Liu wrote:
> Thanks for quick answer!
> Then if broken-cd/SDHCI_QUIRK_BROKEN_CARD_DETECTION is selected, can I
> use host controller Present State Register[18] (offset 0x24) to know
> card status (present or not)?

sdhci.c:

	present = mmc_gpio_get_cd(host->mmc);
	if (present < 0) {
		/* If polling, assume that the card is always present. */
		if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
			present = 1;
		else
			present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
					SDHCI_CARD_PRESENT;
	}

- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child

Re: [Question] What does SDHCI_QUIRK_BROKEN_CARD_DETECTION stands for?

[Kevin Liu]

2013/2/27 Chris Ball <cjb@laptop.org>:
> Hi,
>
> On Wed, Feb 27 2013, Kevin Liu wrote:
>> Thanks for quick answer!
>> Then if broken-cd/SDHCI_QUIRK_BROKEN_CARD_DETECTION is selected, can I
>> use host controller Present State Register[18] (offset 0x24) to know
>> card status (present or not)?
>
> sdhci.c:
>
>         present = mmc_gpio_get_cd(host->mmc);
>         if (present < 0) {
>                 /* If polling, assume that the card is always present. */
>                 if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
>                         present = 1;
>                 else
>                         present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
>                                         SDHCI_CARD_PRESENT;
>         }
>

I just want to confirm this code:)
Then when SDHCI_QUIRK_BROKEN_CARD_DETECTION is selected, read register
SDHCI_PRESENT_STATE is _not_ reliable.
I'm clear now.

Thanks
Kevin