+Mark, On 09/01/15 15:50, Tomi Valkeinen wrote: > On 07/01/15 16:32, Roger Quadros wrote: >> use of regmap_read() and regmap_write() in c_can_hw_raminit_syscon() >> is not safe as the RAMINIT register can be shared between different drivers >> at least for TI SoCs. >> >> To make the modification atomic we switch to using regmap_update_bits(). >> >> Signed-off-by: Roger Quadros <rogerq@xxxxxx> >> --- >> drivers/net/can/c_can/c_can_platform.c | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c >> index f363972..364209a 100644 >> --- a/drivers/net/can/c_can/c_can_platform.c >> +++ b/drivers/net/can/c_can/c_can_platform.c >> @@ -110,6 +110,10 @@ static void c_can_hw_raminit_syscon(const struct c_can_priv *priv, bool enable) >> */ >> ctrl &= ~(1 << raminit->bits.start); >> ctrl |= 1 << raminit->bits.done; >> + >> + /* we can't use regmap_update_bits here as it will bypass the write >> + * if START is already 0 and DONE is already 1. >> + */ >> regmap_write(raminit->syscon, raminit->reg, ctrl); > > Can you first use update_bits to change either bit, so that this update > will be done? > Initial condition is START=0, DONE=1. Now setting and clearing START bit initiates the start process and will cause the DONE bit to be set after a while. So unfortunately this doesn't work for us. Mark, The problem here is we can't use regmap_update_bits() because we need to write a 1 to the DONE bit to clear it and _regmap_update_bits() doesn't allow us to do that because of commit d91e8db2c3bb regmap: Suppress noop writes in regmap_update_bits() Is reverting it going to cause other issues? If yes then can we have a flag to specify forced update? cheers, -roger [1] - http://lxr.free-electrons.com/source/drivers/base/regmap/regmap.c#L2332 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
