On Wed, Dec 15, 2021 at 05:12:00PM +0200, Jarkko Nikula wrote: > From: Tamal Saha <tamal.saha@xxxxxxxxx> > > Intel Keem Bay platform supports multi-master operations over same i2c > bus using Synopsys i2c DesignWare IP. When multi-masters initiate i2c > operation simultaneously in a loop, SCL line is stucked low forever > after few i2c operations. Following interrupt sequences are observed > in: > working case: TX_EMPTY, RX_FULL and STOP_DET > non working case: TX_EMPTY, STOP_DET, RX_FULL. > > DW_apb_i2c stretches the SCL line when the TX FIFO is empty or when > RX FIFO is full. The DW_apb_i2c master will continue to hold the SCL > line LOW until RX FIFO is read. > > Linux kernel i2c DesignWare driver does not handle above non working > sequence. TX_EMPTY, RX_FULL and STOP_DET routine execution are required > in sequence although RX_FULL interrupt is raised after STOP_DET by > hardware. Clear STOP_DET for the following conditions: > (STOP_DET ,RX_FULL, rx_outstanding) > Write Operation: (1, 0, 0) > Read Operation: > RX_FULL followed by STOP_DET: (0, 1, 1) -> (1, 0, 0) > STOP_DET followed by RX_FULL: (1, 0, 1) -> (1, 1, 0) > RX_FULL and STOP_DET together: (1, 1, 1) > > Signed-off-by: Tamal Saha <tamal.saha@xxxxxxxxx> > Signed-off-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx> Applied to for-next, thanks!
Attachment:
signature.asc
Description: PGP signature
