i2c-at91: Mark as broken

24d0fb42 · David Brownell <[email protected]> · 2007-10-13 23:56:32 +02:00

Mark the i2c-at91 driver BROKEN in Kconfig, and explain just
why it's broken.  (Summary:  hardware design issues.)

Signed-off-by: David Brownell <[email protected]>
Signed-off-by: Jean Delvare <[email protected]>

Commit: 24d0fb423ca18adf509dec8a7326c0bdd6653e41
Parents: 08fb68bb

Changes

1 files changed · +9 −1

File	Status	Add	Del	Content
drivers/i2c/busses/Kconfig	modified	+9	−1	View file

drivers/i2c/busses/Kconfig

View file

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index a9cab3e..de95c75 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -75,11 +75,19 @@ config I2C_AMD8111
 
 config I2C_AT91
 	tristate "Atmel AT91 I2C Two-Wire interface (TWI)"
-	depends on ARCH_AT91 && EXPERIMENTAL
+	depends on ARCH_AT91 && EXPERIMENTAL && BROKEN
 	help
 	  This supports the use of the I2C interface on Atmel AT91
 	  processors.
 
+	  This driver is BROKEN because the controller which it uses
+	  will easily trigger RX overrun and TX underrun errors.  Using
+	  low I2C clock rates may partially work around those issues
+	  on some systems.  Another serious problem is that there is no
+	  documented way to issue repeated START conditions, as needed
+	  to support combined I2C messages.  Use the i2c-gpio driver
+	  unless your system can cope with those limitations.
+
 config I2C_AU1550
 	tristate "Au1550/Au1200 SMBus interface"
 	depends on SOC_AU1550 || SOC_AU1200