Re: [PATCH 05/19] coresight: trbe: Refactor status clearing
From: Anshuman Khandual <hidden>
Date: 2025-12-04 12:57:36
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linux-perf-users, lkml
On 01/12/25 4:51 PM, Leo Yan wrote:
If the driver does not clear the status when disabling the trace buffer unit, stale state will carry over to the next enable, though the driver clears it again on enable.
There is no problem now ! Because trbe_enable_hw() calls clr_trbe_status().
Explicitly clear status after the trace is disabled in the interrupt handling and when a perf session ends. Keep the status for spurious interrupts for continuous tracing.
But is not that the behaviour already without this change ? clr_trbe_status() in trbe_enable_hw() ensures that no TRBE session can be started without first clearing the existing status. Still wondering what is the purpose of this change ?
quoted hunk ↗ jump to hunk
Signed-off-by: Leo Yan <leo.yan@arm.com> --- drivers/hwtracing/coresight/coresight-trbe.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index e426991e2c2c398a9d3982e9d0f7f542e404cbab..9e565122816949b37b8ff5e4ba04cfbc317c6f25 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c@@ -629,7 +629,6 @@ static void trbe_enable_hw(struct trbe_buf *buf) WARN_ON(buf->trbe_hw_base < buf->trbe_base); WARN_ON(buf->trbe_write < buf->trbe_hw_base); WARN_ON(buf->trbe_write >= buf->trbe_limit); - clr_trbe_status(); set_trbe_base_pointer(buf->trbe_hw_base); set_trbe_write_pointer(buf->trbe_write);@@ -1036,6 +1035,8 @@ static int arm_trbe_disable(struct coresight_device *csdev) return -EINVAL; trbe_drain_and_disable_local(cpudata); + clr_trbe_status(); + buf->cpudata = NULL; cpudata->buf = NULL; cpudata->mode = CS_MODE_DISABLED;@@ -1151,6 +1152,10 @@ static irqreturn_t arm_trbe_irq_handler(int irq, void *dev) return IRQ_NONE; act = trbe_get_fault_act(handle, status); + + if (act != TRBE_FAULT_ACT_SPURIOUS) + clr_trbe_status(); + switch (act) { case TRBE_FAULT_ACT_WRAP: truncated = !!trbe_handle_overflow(handle);