Re: [PATCH 3/3] mmc: tmio: support IP-builtin card detection logic

From: Masahiro Yamada
Date: Mon Nov 20 2017 - 03:04:20 EST

2017-11-20 4:45 GMT+09:00 Wolfram Sang <wsa@xxxxxxxxxxxxx>:
> On Wed, Nov 08, 2017 at 07:17:00PM +0900, Masahiro Yamada wrote:
>> A card detect GPIO is set up only for platforms with "cd-gpios"
>> DT property or TMIO_MMC_USE_GPIO_CD flag. However, the driver
>> core always uses mmc_gpio_get_cd, which just fails with -ENOSYS
>> if ctx->cd_gpio is unset.
>> The bit 5 of the status register provides the current signal level
>> of the CD line. Allow to use it if the GPIO is unused.
> I might be missing something: Why do we need to report something
> sensible in this case? The card insert/eject interrupts calling
> mmc_detect_change is not enough?

Not enough.

mmc_detect_change() just schedules mmc_rescan().

Without correct ->get_cd(), how can mmc_rescan()
know whether a card is inserted or not?

Best Regards
Masahiro Yamada