On 07/06/2010 08:42 PM, ext Nicolas Pitre wrote:
On Tue, 6 Jul 2010, Roger Quadros wrote:
On 07/06/2010 03:53 PM, ext Ohad Ben-Cohen wrote:
Hi Roger,
On Tue, Jul 6, 2010 at 1:35 PM, Roger Quadros<roger.quadros@xxxxxxxxx>
wrote:
My point is that shouldn't this be handled by SDIO core?
Care to explain what you mean / give a code example ?
If the Power enable GPIO can be treated as SDIO slot supply (i.e. vmmc), then
the SDIO/MMC core should tackle it, just like it deals with supply for slots
with removable cards.
Exact.
You need card detect events in order to trigger card& sdio function
initialization and removals.
Why would you trigger function initialization and removal? Just to turn
off power? That's a bit like pulling off the battery from your laptop
when you want to suspend it. There is a better way to go about things.
Please share any alternative approach you may be thinking on.
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.
if we have sdio_claim_power() and sdio_release_power() in place then power
control should depend on it.
regards,
-roger
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