On 3/21/24 12:31, Tomi Valkeinen wrote: > On 21/03/2024 18:08, Sean Anderson wrote: >> On 3/20/24 03:49, Tomi Valkeinen wrote: >>> On 20/03/2024 00:51, Sean Anderson wrote: >>> >>>> +/** >>>> + * enum test_pattern - Test patterns for test testing >>> >>> "for test testing"? =) >>> >>>> @@ -1655,6 +2321,9 @@ static void zynqmp_dp_hpd_irq_work_func(struct >>>> work_struct *work) >>>> u8 status[DP_LINK_STATUS_SIZE + 2]; >>>> int err; >>>> + if (READ_ONCE(dp->ignore_hpd)) >>>> + return; >>>> + >>>> mutex_lock(&dp->lock); >>>> err = drm_dp_dpcd_read(&dp->aux, DP_SINK_COUNT, status, >>>> DP_LINK_STATUS_SIZE + 2); >>> >>> Why do you need READ/WRITE_ONCE() for ignore_hpd? >> >> It's not protected by dp->lock so we don't have to take it for >> zynqmp_dp_hpd_work_func. Although maybe we should make a version of >> zynqmp_dp_bridge_detect which assumes we already hold the lock. > > Does using the macros solve some potential issue, or is it just for > documenting that this variable is accessed without lock?
Without this the compiler is free to issue multiple loads for this variable, which could be incorrect. --Sean
