On Wed, 7 Jul 2010, Roger Quadros wrote: > On 07/06/2010 08:42 PM, ext Nicolas Pitre wrote: > > On Tue, 6 Jul 2010, Roger Quadros wrote: > > > > > OK, this is how I see it. > > > > > > - Treat the non-removable card as non-removable. So no need to do card > > > detect > > > emulation. > > > > > > - Treat the GPIO power enable on wl1271 as VMMC supply. Use fixed > > > regulator > > > framework to define this regulator& supply. Even though you mention that > > > it > > > is not actually a supply, it fits well in the fixed supply framework. > > > > > > - When the host controller is enumerated, the mmc core will power up the > > > slot, > > > find the sdio card, and probe the function driver (i.e. wl1271_sdio). > > > > > > - if interface is not in use, the function driver must release the sdio > > > host, > > > and this should eventually disable the vmmc supply. > > > > > > - Whenever the wlan interface must be brought up, wl1271_sdio, can claim > > > the > > > sdio host. this will cause the vmmc supply to be enabled, for as long as > > > the > > > interface is up. > > > > > > Does this address all issues? > > > > This is mostly all good, except that claiming/releasing the SDIO host is > > about access to the bus. It must be claimed right before doing any IO, > > and released right after that, even when the card is expected to remain > > powered. This is not the proper place to hook power control. > > Agreed, but is it so that SDIO power may be removed between a host_release and > claim? This appears so from omap_hsmmc host controller. No, it is not because a host is not claimed that power should be dropped. The host claim/release is meant to provide exclusive access to the card that's all. If the OMAP controller is dropping power to the card upon host->disable() then it is wrong. AFAICS only the OMAP controller is playing such games at the moment and I suspect the semantics might not be all right. Shutting down the _controller_ when it is idle might be a good thing, but not power to the _card_. Only the function driver might know when it is fine to lose power. Nicolas -- 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
