410a1da7ee
[ Upstream commit 212709926c5493a566ca4086ad4f4b0d4e66b553 ]
When the timer is configured in posted mode, we need to check the write-
posted status register (TWPS) before writing to the register.
We now check TWPS after the write starting with commit 52762fbd1c47
("clocksource/drivers/timer-ti-dm: Add clockevent and clocksource
support").
For example, in the TRM for am571x the following is documented in chapter
"22.2.4.13.1.1 Write Posting Synchronization Mode":
"For each register, a status bit is provided in the timer write-posted
status (TWPS) register. In this mode, it is mandatory that software check
this status bit before any write access. If a write is attempted to a
register with a previous access pending, the previous access is discarded
without notice."
The regression happened when I updated the code to use standard read/write
accessors for the driver instead of using __omap_dm_timer_load_start().
We have__omap_dm_timer_load_start() check the TWPS status correctly using
__omap_dm_timer_write().
Fixes: 52762fbd1c47 ("clocksource/drivers/timer-ti-dm: Add clockevent and clocksource support")
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210304072135.52712-2-tony@atomide.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
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