On 21/02/2025 10:49, Alessio Belle wrote:
> When firmware traces are enabled, the firmware dumps 48-bit timestamps
> for each trace as two 32-bit values, highest 32 bits (of which only 16
> useful) first.
>
> The driver was reassembling them the other way round i.e. interpreting
> the first value in memory as the lowest 32 bits, and the second value
> as the highest 32 bits (then truncated to 16 bits).
>
> Due to this, firmware trace dumps showed very large timestamps even for
> traces recorded shortly after GPU boot. The timestamps in these dumps
> would also sometimes jump backwards because of the truncation.
>
> Example trace dumped after loading the powervr module and enabling
> firmware traces, where each line is commented with the timestamp value
> in hexadecimal to better show both issues:
>
> [93540092739584] : Host Sync Partition marker: 1 // 0x551300000000
> [28419798597632] : GPU units deinit // 0x19d900000000
> [28548647616512] : GPU deinit // 0x19f700000000
>
> Update logic to reassemble the timestamps halves in the correct order.
>
> Fixes: cb56cd610866 ("drm/imagination: Add firmware trace to debugfs")
> Signed-off-by: Alessio Belle <[email protected]>Reviewed-by: Matt Coster <[email protected]> Cheers, Matt > --- > drivers/gpu/drm/imagination/pvr_fw_trace.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/imagination/pvr_fw_trace.c > b/drivers/gpu/drm/imagination/pvr_fw_trace.c > index > 73707daa4e52d13fd1388cb2e9feff0aea109620..5dbb636d7d4ffeea2253ea58e817710979f90cf0 > 100644 > --- a/drivers/gpu/drm/imagination/pvr_fw_trace.c > +++ b/drivers/gpu/drm/imagination/pvr_fw_trace.c > @@ -333,8 +333,8 @@ static int fw_trace_seq_show(struct seq_file *s, void *v) > if (sf_id == ROGUE_FW_SF_LAST) > return -EINVAL; > > - timestamp = read_fw_trace(trace_seq_data, 1) | > - ((u64)read_fw_trace(trace_seq_data, 2) << 32); > + timestamp = ((u64)read_fw_trace(trace_seq_data, 1) << 32) | > + read_fw_trace(trace_seq_data, 2); > timestamp = (timestamp & ~ROGUE_FWT_TIMESTAMP_TIME_CLRMSK) >> > ROGUE_FWT_TIMESTAMP_TIME_SHIFT; > > > --- > base-commit: 938fbb16aba8f7b88e0fdcf56f315a5bbad41aad > change-id: 20250220-fix-fw-trace-timestamps-15d70bb2d93d > > Best regards, > -- > Alessio Belle <[email protected]> > -- Matt Coster E: [email protected]
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