When trying to use CMT for clockevents on R-Car gen3 SoCs, I noticed that the maximum delta (in ns) for the broadcast timer was diplayed as 1000 in /proc/timer_list. It turned out that when calculating it, the driver did shift left 1 by 32 (causing what I think was undefined behaviour) getting 1 as a result. Using 1UL instead fixed the maximum delta and did even fix switching an active clocksource to a CMT channel (which caused the system to go non-interactive before).
Signed-off-by: Sergei Shtylyov <[email protected]> --- This patch is against the 'tip.git' repo's 'timers/core' branch. I am not sure whether the CMT driver was ever used on SH64; on R-Car gen3 (ARM64) I'm only enabling this driver now, so not sure how urgent is this... drivers/clocksource/sh_cmt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: tip/drivers/clocksource/sh_cmt.c =================================================================== --- tip.orig/drivers/clocksource/sh_cmt.c +++ tip/drivers/clocksource/sh_cmt.c @@ -891,7 +891,7 @@ static int sh_cmt_setup_channel(struct s if (cmt->info->width == (sizeof(ch->max_match_value) * 8)) ch->max_match_value = ~0; else - ch->max_match_value = (1 << cmt->info->width) - 1; + ch->max_match_value = (1UL << cmt->info->width) - 1; ch->match_value = ch->max_match_value; raw_spin_lock_init(&ch->lock);
