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| author | Lukasz Majewski <lukma@denx.de> | 2019-04-04 12:35:34 +0200 |
|---|---|---|
| committer | Heiko Schocher <hs@denx.de> | 2019-04-11 15:21:33 +0200 |
| commit | a40fe217d19fdb9804fdc88342ce4bb0a0440c84 (patch) | |
| tree | 07fc2927d51569ad0614579c3e22f947e3eb8851 /doc/README.sata | |
| parent | 3c99166441bf3ea325af2da83cfe65430b49c066 (diff) | |
| download | u-boot-a40fe217d19fdb9804fdc88342ce4bb0a0440c84.zip u-boot-a40fe217d19fdb9804fdc88342ce4bb0a0440c84.tar.gz u-boot-a40fe217d19fdb9804fdc88342ce4bb0a0440c84.tar.bz2 | |
DM: I2C: Introduce 'u-boot, i2c-transaction-bytes' property
The 'u-boot,i2c-transaction-bytes' device tree property provides
information regarding number of bytes transferred by a device in a
single transaction.
This change is necessary to avoid hanging devices after soft reset.
One notable example is communication with MC34708 device:
1. Reset when communicating with MC34708 via I2C.
2. The u-boot (after reboot -f) tries to setup the I2C and then calls
force_idle_bus. In the same time MC34708 still has some data to be sent
(as it transfers data in 24 bits chunks).
3. The force_idle_bus() is not able to make the bus idle as 8 SCL
clocks may be not enough to have the full transmission.
4. We end up with I2C inconsistency with MC34708.
This PMIC device requires 24+ SCL cycles to make finish any pending I2C
transmission.
Signed-off-by: Lukasz Majewski <lukma@denx.de>
Diffstat (limited to 'doc/README.sata')
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