On Tue, Aug 15, 2017 at 04:51:02PM +0930, Andrew Jeffery wrote: > In addition to the base, low and high clock configuration, the AC timing > register #1 on the AST2400 houses fields controlling: > > 1. tBUF: Minimum delay between Stop and Start conditions > 2. tHDSTA: Hold time for the Start condition > 3. tACST: Setup time for Start and Stop conditions, and hold time for the > Repeated Start condition > > These values are defined in hardware on the AST2500 and therefore don't > need to be set. > > aspeed_i2c_init_clk() was performing a direct write of the generated > clock values rather than a read/mask/modify/update sequence to retain > tBUF, tHDSTA and tACST, and therefore cleared the tBUF, tHDSTA and tACST > fields on the AST2400. This resulted in a delay/setup/hold time of 1 > base clock, which in some configurations is not enough for some devices > (e.g. the MAX31785 fan controller, with an APB of 48MHz and a desired > bus speed of 100kHz). > > Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx> Applied to for-next, thanks! I even considered for-current but it does not apply there. So, I leave the backporting for the interested parties :)
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