On 28 April 2014 11:36, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > On Mon, Apr 28, 2014 at 11:31:03AM +0200, Ulf Hansson wrote: >> On 28 April 2014 11:13, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: >> > On Sat, Apr 19, 2014 at 11:59:18PM +0200, Daniel Willmann wrote: >> >> Return -ENOSYS in get_cd if broken-cd is specified in the device tree. >> >> >> >> Commit a91fe279ae75 (mmc: mxs: use standard flag for broken card >> >> detection) sets MMC_CAP_NEEDS_POLL when broken-cd is specified. This >> >> driver sets this flag unconditionally as it does not support a card >> >> detect interrupt. Instead, broken-cd means that there is no card detect >> >> signal connected. >> >> >> >> The mmc core checks the get_cd function return value to determine if a >> >> card is present. Only for a non-zero return value it will attempt to >> >> initialize the card. So retuning -ENOSYS will allow the card to be >> >> initialized. >> >> For comparison, mmc_gpio_get_cd in slot-gpio.c also returns -ENOSYS if >> >> the card detect GPIO is not valid. >> > >> > Short answer for fixing this regression: >> > >> > Acked-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> >> > >> > Long answer: >> > >> > This is broken in the MMC OF parser. When the parser finds the >> > 'broken-cd' property it just sets the MMC_CAP_NEEDS_POLL flag. This is >> > wrong. broken-cd means that we cannot rely on any card detection, but >> > instead have to talk to the card to find out if it's available. >> > Currently there is no flag to signal this situation, so the host driver >> > has to handle this by returning true in the get_cd callback, just like >> > the patch below does. >> > >> > IMO the correct solution would be to add a MMC_CAP_CD_NEEDS_TALK_TO_CARD >> > flag to the core. >> > >> >> So if I understand correct, you want the host-ops->get_cd function to >> be invoked from the mmc rescan - only when it actually can provide >> useful information? > > Yes. Until/if that happens, I suggest to go ahead with Daniel's patch as well. Acked-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > > Sascha > > -- > Pengutronix e.K. | | > Industrial Linux Solutions | http://www.pengutronix.de/ | > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
