4.19-stable review patch. If anyone has any objections, please let me know.
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From: Jacky Bai ping.bai@nxp.com
commit 3d5c2f8e75a55cfb11a85086c71996af0354a1fb upstream.
The value written into the TPM CnV can only be updated into the hardware when the counter increases. Additional writes to the CnV write buffer are ignored until the register has been updated. Therefore, we need to check if the CnV has been updated before continuing. This may require waiting for 1 counter cycle in the worst case.
Cc: stable@vger.kernel.org Fixes: 059ab7b82eec ("clocksource/drivers/imx-tpm: Add imx tpm timer support") Signed-off-by: Jacky Bai ping.bai@nxp.com Reviewed-by: Peng Fan peng.fan@nxp.com Reviewed-by: Ye Li ye.li@nxp.com Reviewed-by: Jason Liu jason.hui.liu@nxp.com Signed-off-by: Frank Li Frank.Li@nxp.com Link: https://lore.kernel.org/r/20240725193355.1436005-2-Frank.Li@nxp.com Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/clocksource/timer-imx-tpm.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/drivers/clocksource/timer-imx-tpm.c +++ b/drivers/clocksource/timer-imx-tpm.c @@ -104,6 +104,14 @@ static int tpm_set_next_event(unsigned l now = tpm_read_counter();
/* + * Need to wait CNT increase at least 1 cycle to make sure + * the C0V has been updated into HW. + */ + if ((next & 0xffffffff) != readl(timer_base + TPM_C0V)) + while (now == tpm_read_counter()) + ; + + /* * NOTE: We observed in a very small probability, the bus fabric * contention between GPU and A7 may results a few cycles delay * of writing CNT registers which may cause the min_delta event got