> Subject: [PATCH v2 05/10] drm/i915/cmtg: program set context latency of
> cmtg

* CMTG

> 
> Program context latency for delayed vblank timings to create window2.
> 

Bspec link

> Signed-off-by: Animesh Manna <[email protected]>
> ---
>  drivers/gpu/drm/i915/display/intel_cmtg.c      | 4 ++++
>  drivers/gpu/drm/i915/display/intel_cmtg_regs.h | 2 ++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_cmtg.c
> b/drivers/gpu/drm/i915/display/intel_cmtg.c
> index 26adf70cdd00..cb1376f4c13f 100644
> --- a/drivers/gpu/drm/i915/display/intel_cmtg.c
> +++ b/drivers/gpu/drm/i915/display/intel_cmtg.c
> @@ -236,10 +236,14 @@ static void intel_cmtg_set_timings(const struct
> intel_crtc_state *crtc_state)
> 
>  void intel_cmtg_enable(const struct intel_crtc_state *crtc_state)  {
> +     struct intel_display *display = to_intel_display(crtc_state);
>       enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
> 
>       if (cpu_transcoder != TRANSCODER_A && cpu_transcoder !=
> TRANSCODER_B)
>               return;
> 
>       intel_cmtg_set_timings(crtc_state);
> +
> +     intel_de_write(display,
> TRANS_SET_CTX_LATENCY_CMTG(cpu_transcoder),
> +                    intel_de_read(display,
> TRANS_SET_CONTEXT_LATENCY(display,
> +cpu_transcoder)));

So at least three things need to change here:
- We are actively trying to move away from doing inline intel_de_reads like 
this with arguments passed to function.
- We also try not to read from HW and write back to HW . We need to write our 
derived S/w value to HW. Readback needs to only
be for verification purpose. We only use H/w read when we are sort of out of 
options on a viable solution to derive the value at that place.
>From what I can see since you are using the exact values that is coded in 
>TRANS_CONTEXT_LATENCY your work can be done by crtc_state->set_context_latency
- This belongs in intel_cmtg_set_timings (which I said before needs to be 
called from intel_set_transcoder_timings ( Also I think you should rename 
function to intel_cmtg_set_transcoder_timings))


>  }
> diff --git a/drivers/gpu/drm/i915/display/intel_cmtg_regs.h
> b/drivers/gpu/drm/i915/display/intel_cmtg_regs.h
> index eab90415d0da..3cfd8eedb321 100644
> --- a/drivers/gpu/drm/i915/display/intel_cmtg_regs.h
> +++ b/drivers/gpu/drm/i915/display/intel_cmtg_regs.h
> @@ -32,4 +32,6 @@
>  #define TRANS_VRR_VMIN_CMTG(id)              _MMIO(0x6F434 + (id) *
> 0x100)
>  #define TRANS_VRR_FLIPLINE_CMTG(id)  _MMIO(0x6F438 + (id) *
> 0x100)
> 
> +#define TRANS_SET_CTX_LATENCY_CMTG(id) _MMIO(0x6F07C + (id) *
> 0x100)
> +

Usually we call this index instead of id

Regards,
Suraj Kandpal

>  #endif /* __INTEL_CMTG_REGS_H__ */
> --
> 2.29.0

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