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mmc: if possible, poll the busy state using DAT0

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Using the DAT0 line as a rdy/busy line is an alternative to reading the
status register of the card. It especially useful in situation where the
bus is not in a good shape, like when modes are switched.
This is also how the linux driver behaves.

Note of warning: As per the specification, while polling on DAT0 the CLK
must not turned off: "[...] Without a clock edge the Device (unless
previously disconnected by a deselect command (CMD7)) will force the DAT0
line down, forever. [...]"

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
This commit is contained in:
Jean-Jacques Hiblot 2019-07-02 10:53:53 +02:00 • committed by Peng Fan
parent 863d10044a
commit cd0b80ec9c
3 changed files with 4 additions and 6 deletions
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2
include/mmc.h
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@ -445,7 +445,6 @@ struct dm_mmc_ops {
int (*execute_tuning)(struct udevice *dev, uint opcode);
#endif
#if CONFIG_IS_ENABLED(MMC_UHS_SUPPORT)
/**
* wait_dat0() - wait until dat0 is in the target state
* (CLK must be running during the wait)
@ -456,7 +455,6 @@ struct dm_mmc_ops {
* @return 0 if dat0 is in the target state, -ve on error
*/
int (*wait_dat0)(struct udevice *dev, int state, int timeout);
#endif
};
#define mmc_get_ops(dev) ((struct dm_mmc_ops *)(dev)->driver->ops)