[PATCH 2/8] i2c: at91: add warning about transmission issues for some devices
From: Voss, Nikolaus <hidden>
Date: 2012-09-03 05:54:35
Also in:
linux-devicetree, linux-i2c
ludovic.desroches at atmel.com wrote on Friday, August 31, 2012 11:21 AM
From: Ludovic Desroches <redacted> Some devices don't have clock streching in transmission mode. It can lead to premature stop sendings if the latency to write data in the transmission register is too long. In this case, prefer the i2c-gpio driver. Signed-off-by: Ludovic Desroches <redacted>
Acked-by: Nikolaus Voss <redacted>
quoted hunk
--- drivers/i2c/busses/Kconfig | 6 ++++++ 1 file changed, 6 insertions(+)diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index d9c4918..da77c37 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig@@ -300,6 +300,12 @@ config I2C_AT91 to support combined I2C messages. Use the i2c-gpio driver unless your system can cope with this limitation. + Caution! at91rm9200, at91sam9261, at91sam9260, at91sam9263devices + don't have clock stretching in transmission mode. For that reason, + you can encounter underrun issues causing premature stop sendings if + the latency to fill the transmission register is too long. If you + are facing this situation, use the i2c-gpio driver. + config I2C_AU1550 tristate "Au1550/Au1200/Au1300 SMBus interface" depends on MIPS_ALCHEMY -- 1.7.11.3