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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 /drivers/i2c/i2c-uclass.c | |
| parent | 3c99166441bf3ea325af2da83cfe65430b49c066 (diff) | |
| download | u-boot-a40fe217d19fdb9804fdc88342ce4bb0a0440c84.tar.gz | |
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 'drivers/i2c/i2c-uclass.c')
| -rw-r--r-- | drivers/i2c/i2c-uclass.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c index 49e23a0a4b..e47abf1833 100644 --- a/drivers/i2c/i2c-uclass.c +++ b/drivers/i2c/i2c-uclass.c @@ -593,6 +593,29 @@ int i2c_chip_ofdata_to_platdata(struct udevice *dev, struct dm_i2c_chip *chip) } #endif +static int i2c_pre_probe(struct udevice *dev) +{ +#if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA) + struct dm_i2c_bus *i2c = dev_get_uclass_priv(dev); + unsigned int max = 0; + ofnode node; + int ret; + + i2c->max_transaction_bytes = 0; + dev_for_each_subnode(node, dev) { + ret = ofnode_read_u32(node, + "u-boot,i2c-transaction-bytes", + &max); + if (!ret && max > i2c->max_transaction_bytes) + i2c->max_transaction_bytes = max; + } + + debug("%s: I2C bus: %s max transaction bytes: %d\n", __func__, + dev->name, i2c->max_transaction_bytes); +#endif + return 0; +} + static int i2c_post_probe(struct udevice *dev) { #if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA) @@ -674,6 +697,7 @@ UCLASS_DRIVER(i2c) = { .post_bind = i2c_post_bind, .init = i2c_uclass_init, .priv_auto_alloc_size = sizeof(struct i2c_priv), + .pre_probe = i2c_pre_probe, .post_probe = i2c_post_probe, .per_device_auto_alloc_size = sizeof(struct dm_i2c_bus), .per_child_platdata_auto_alloc_size = sizeof(struct dm_i2c_chip), |