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linux/drivers/i2c
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Noralf Trønnes 938f8e8560 i2c: bcm2835: Fix hang for writing messages larger than 16 bytes 
commit e247454103 upstream.

Writing messages larger than the FIFO size results in a hang, rendering
the machine unusable. This is because the RXD status flag is set on the
first interrupt which results in bcm2835_drain_rxfifo() stealing bytes
from the buffer. The controller continues to trigger interrupts waiting
for the missing bytes, but bcm2835_fill_txfifo() has none to give.
In this situation wait_for_completion_timeout() apparently is unable to
stop the madness.

The BCM2835 ARM Peripherals datasheet has this to say about the flags:
  TXD: is set when the FIFO has space for at least one byte of data.
  RXD: is set when the FIFO contains at least one byte of data.
  TXW: is set during a write transfer and the FIFO is less than full.
  RXR: is set during a read transfer and the FIFO is or more full.

Implementing the logic from the downstream i2c-bcm2708 driver solved
the hang problem.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2017-04-18 07:11:47 +02:00
..
algos i2c: algo-bit: declare i2c_bit_quirk_no_clk_stretch as static 2016-05-11 17:16:30 +02:00
busses i2c: bcm2835: Fix hang for writing messages larger than 16 bytes 2017-04-18 07:11:47 +02:00
muxes i2c: mux: pca954x: fix i2c mux selection caching 2017-01-19 20:18:05 +01:00
i2c-boardinfo.c i2c: remove __init from i2c_register_board_info() 2016-06-19 14:13:50 +02:00
i2c-core.c i2c: print correct device invalid address 2017-01-19 20:18:02 +01:00
i2c-core.h i2c: remove FSF address 2014-11-07 18:35:33 +01:00
i2c-dev.c i2c: fix kernel memory disclosure in dev interface 2017-01-19 20:18:02 +01:00
i2c-mux.c i2c: add missing of_node_put in i2c_mux_del_adapters 2017-03-18 19:14:30 +08:00
i2c-slave-eeprom.c i2c: Drop owner assignment from i2c_driver 2015-08-10 08:37:35 +02:00
i2c-smbus.c i2c: i2c-smbus: fix i2c_handle_smbus_host_notify documentation 2016-07-18 20:09:54 +02:00
i2c-stub.c i2c: i2c-stub: sort includes 2016-02-20 23:33:39 +01:00
Kconfig i2c: mux: fix up dependencies 2016-11-14 18:23:30 +01:00
Makefile i2c: slave-eeprom: add eeprom simulator driver 2014-12-11 22:25:54 +01:00