Re: [PATCH 5/7] drm/xe: Add helper to capture engine timestamp

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>]

On Tue, Apr 16, 2024 at 10:14:28PM -0500, Lucas De Marchi wrote:
>On Tue, Apr 16, 2024 at 03:56:29PM GMT, Umesh Nerlige Ramappa wrote:
>>On Mon, Apr 15, 2024 at 08:04:52PM -0700, Lucas De Marchi wrote:
>>>Just like CTX_TIMESTAMP is used to calculate runtime, add a helper to
>>>get the timestamp for the engine so it can be used to calculate the
>>>"engine time" with the same unit as the runtime is recorded.
>>>
>>>Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
>>
>>Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
>>
>>>---
>>>drivers/gpu/drm/xe/xe_hw_engine.c | 7 +++++++
>>>drivers/gpu/drm/xe/xe_hw_engine.h | 2 ++
>>>files changed, 9 insertions(+)
>>>
>>>diff --git a/drivers/gpu/drm/xe/xe_hw_engine.c b/drivers/gpu/drm/xe/xe_hw_engine.c
>>>index ab227fa8984a..528b271c9f23 100644
>>>--- a/drivers/gpu/drm/xe/xe_hw_engine.c
>>>+++ b/drivers/gpu/drm/xe/xe_hw_engine.c
>>>@@ -981,3 +981,10 @@ const char *xe_hw_engine_class_to_str(enum xe_engine_class class)
>>>
>>>	return NULL;
>>>}
>>>+
>>>+u64 xe_hw_engine_read_timestamp(struct xe_hw_engine *hwe)
>>>+{
>>>+	struct xe_reg reg = RING_TIMESTAMP(hwe->mmio_base);
>>>+
>>>+	return xe_mmio_read64_2x32(hwe->gt, reg);
>
>given the past issues with reading 64b registers, I'm wondering if we
>shouldn't export a xe_hw_engine_read_timestamp32 and use just the lower
>part. Since the CTX_TIMESTAMP will wrap around first, just using 32b
>for RING_TIMESTAMP should be sufficient.

Yeah that works too.

Regards,
Umesh

>
>Lucas De Marchi