From d066b246d482f69553e58d52f746377ce3966b66 Mon Sep 17 00:00:00 2001 From: Russell King Date: Tue, 20 Feb 2018 10:22:22 +0100 Subject: [PATCH] drm/etnaviv: correct timeout calculation The old way did clamp the jiffy conversion and thus caused the timeouts to become negative after some time. Also it didn't work with userspace which actually fills the upper 32bits of the 64bit timestamp value. clock_gettime() is 32-bit on 32-bit architectures. Using 64-bit timespec math, like we do in this commit, means that when a wrap occurs, the specified timeout goes into the past and we can't request a timeout in the future. As the Linux implementation of CLOCK_MONOTONIC is reasonable and starts at 0, the first such timer wrap will occur after approx. 68 years of system uptime. Signed-off-by: Russell King Signed-off-by: Lucas Stach --- drivers/gpu/drm/etnaviv/etnaviv_drv.h | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h index ddb17ee565e9..17a43da98fb9 100644 --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -132,19 +133,27 @@ static inline bool fence_after_eq(u32 a, u32 b) return (s32)(a - b) >= 0; } +/* + * Etnaviv timeouts are specified wrt CLOCK_MONOTONIC, not jiffies. + * We need to calculate the timeout in terms of number of jiffies + * between the specified timeout and the current CLOCK_MONOTONIC time. + */ static inline unsigned long etnaviv_timeout_to_jiffies( const struct timespec *timeout) { - unsigned long timeout_jiffies = timespec_to_jiffies(timeout); - unsigned long start_jiffies = jiffies; - unsigned long remaining_jiffies; + struct timespec64 ts, to; - if (time_after(start_jiffies, timeout_jiffies)) - remaining_jiffies = 0; - else - remaining_jiffies = timeout_jiffies - start_jiffies; + to = timespec_to_timespec64(*timeout); - return remaining_jiffies; + ktime_get_ts64(&ts); + + /* timeouts before "now" have already expired */ + if (timespec64_compare(&to, &ts) <= 0) + return 0; + + ts = timespec64_sub(to, ts); + + return timespec64_to_jiffies(&ts); } #endif /* __ETNAVIV_DRV_H__ */