RE: [PATCH 1/3i v6] MMC/SD: Add callback function to detect card

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> -----Original Message-----
> From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Kevin Liu
> Sent: Friday, March 22, 2013 2:55 PM
> To: Huang Changming-R66093
> Cc: linux-mmc@xxxxxxxxxxxxxxx; Chris Ball; Ulf Hansson
> Subject: Re: [PATCH 1/3i v6] MMC/SD: Add callback function to detect card
> 
> 2013/3/22 Huang Changming-R66093 <r66093@xxxxxxxxxxxxx>:
> >> Jerry,
> >>
> >> Function _mmc_detect_card_removed should only be called when card
> >> insert/removal or i/o error occur unless POLLING is used(called once
> >> per second). So it should _not_ impact performance much.
> > [jerry]
> > No, your understanding is wrong.
> > Function "_mmc_detect_card_removed " is called to check if our card has
> been removed when driver run the function "mmc_rescan" every time.
> >
> 
> But when will mmc_rescan be called?
> Besides boot up, only when card status change it will be called.
> So usually it should _not_ be called frequently.
[jerry]
For poll mode, how to know card status changed?
The answer is "mmc_rescan".
maybe you could read the last two lines of this function ago.

> >> POLLING is poor for performance, why not change to slot-gpio if host
> >> is broken for card detect.
> > [jerry]
> > Some our boards can't support interrupt mode to detect card
> insert/removable, so we unify the poll mode.
> >
> 
> Not support gpio interrupt?
> I think you only don't support sdh host interrupt.

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