path: root/doc
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authorPeter Tyser <ptyser@xes-inc.com>2010-10-22 00:20:31 -0500
committerKumar Gala <galak@kernel.crashing.org>2010-10-22 02:19:14 -0500
commit9d921f19b3f981a499f49a57e2c3ace7be5aeecc (patch)
treee9ce68653e716c33eed4d28af312f07f18327fb1 /doc
parent60aaaa0782848062d0f499382035acc09eaff352 (diff)
post/i2c: Add ability to ignore I2C devices
Add the ability to not report an I2C POST error for a set of given I2C addresses on bootup. This is useful for cases when a device may or may not be present, and neither case is considered an error. For example: - Some form factors such as XMC and Compact PCI Express have an I2C EEPROM whose address changes based on geographical address. Eg installed in one slot its EEPROM address is, 0x50, in another its 0x51, etc. This allows multiple devices to have their EEPROMs present on the same I2C bus. Thus the I2C devices present for an XMC or CPCIe card depend on if and where other cards are installed in the same system. - Some cards have optional I2C devices. Eg one hardware build configuration has different I2C devices than another and software can't determine if the optional device should be present or not. - Some cards have optional daughtercards with I2C devices on them. - I2C EEPROMs address range depends on their size. Its possible to support differently size EEPROMs by only probing the EEPROM's base address and ignoring the other addresses that are impacted by its size. A new CONFIG_SYS_POST_I2C_IGNORES define has been added which specifies a list of I2C addresses for the I2C POST to ignore. Signed-off-by: Peter Tyser <ptyser@xes-inc.com> Acked-by: Heiko Schocher <hs@denx.de> Acked-by: Wolfgang Denk <wd@denx.de> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Diffstat (limited to 'doc')
1 files changed, 8 insertions, 0 deletions
diff --git a/doc/README.POST b/doc/README.POST
index 695497e4b..6815d491c 100644
--- a/doc/README.POST
+++ b/doc/README.POST
@@ -665,6 +665,14 @@ listed in CONFIG_SYS_POST_I2C_ADDRS are found, and no additional
devices are detected. If CONFIG_SYS_POST_I2C_ADDRS is not defined
the test will pass if any I2C device is found.
+The CONFIG_SYS_POST_I2C_IGNORES define can be used to list I2C
+devices which may or may not be present when using
+CONFIG_SYS_POST_I2C_ADDRS. The I2C POST test will pass regardless
+if the devices in CONFIG_SYS_POST_I2C_IGNORES are found or not.
+This is useful in cases when I2C devices are optional (eg on a
+daughtercard that may or may not be present) or not critical
+to board operation.
+ Watchdog timer test
To test the watchdog timer the scheme mentioned above (refer to