Re: [PATCH 15/16] drm/i915/display: Separate out functions to get/set VTOTAL register

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 3/25/2025 7:15 PM, Ville Syrjälä wrote:
> On Tue, Mar 25, 2025 at 11:52:24AM +0530, Nautiyal, Ankit K wrote:
>> On 3/24/2025 11:32 PM, Ville Syrjälä wrote:
>>> On Mon, Mar 24, 2025 at 07:02:47PM +0530, Ankit Nautiyal wrote:
>>>> Introduce helpers to get and set TRANS_VTOTAL registers.
>>>> This will pave way to avoid reading/writing VTOTAL.Vtotal bits for
>>>> platforms that always use VRR timing generator.
>>>>
>>>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
>>>> ---
>>>>    drivers/gpu/drm/i915/display/intel_display.c | 41 +++++++++++++-------
>>>>    1 file changed, 27 insertions(+), 14 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>>>> index ae1dc32044fb..fa9c6793357e 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>>>> @@ -2638,6 +2638,15 @@ void intel_cpu_transcoder_set_m2_n2(struct intel_crtc *crtc,
>>>>    		      PIPE_LINK_N2(display, transcoder));
>>>>    }
>>>>    
>>>> +static void intel_crtc_set_vtotal(struct intel_display *display,
>>>> +				  enum transcoder cpu_transcoder,
>>>> +				  u32 crtc_vdisplay, u32 crtc_vtotal)
>>>> +{
>>>> +	intel_de_write(display, TRANS_VTOTAL(display, cpu_transcoder),
>>>> +		       VACTIVE(crtc_vdisplay - 1) |
>>>> +		       VTOTAL(crtc_vtotal - 1));
>>>> +}
>>>> +
>>>>    static void intel_set_transcoder_timings(const struct intel_crtc_state *crtc_state)
>>>>    {
>>>>    	struct intel_display *display = to_intel_display(crtc_state);
>>>> @@ -2702,9 +2711,8 @@ static void intel_set_transcoder_timings(const struct intel_crtc_state *crtc_sta
>>>>    		       HSYNC_START(adjusted_mode->crtc_hsync_start - 1) |
>>>>    		       HSYNC_END(adjusted_mode->crtc_hsync_end - 1));
>>>>    
>>>> -	intel_de_write(display, TRANS_VTOTAL(display, cpu_transcoder),
>>>> -		       VACTIVE(crtc_vdisplay - 1) |
>>>> -		       VTOTAL(crtc_vtotal - 1));
>>>> +	intel_crtc_set_vtotal(display, cpu_transcoder, crtc_vdisplay, crtc_vtotal);
>>>> +
>>>>    	intel_de_write(display, TRANS_VBLANK(display, cpu_transcoder),
>>>>    		       VBLANK_START(crtc_vblank_start - 1) |
>>>>    		       VBLANK_END(crtc_vblank_end - 1));
>>>> @@ -2718,9 +2726,8 @@ static void intel_set_transcoder_timings(const struct intel_crtc_state *crtc_sta
>>>>    	 * bits. */
>>>>    	if (display->platform.haswell && cpu_transcoder == TRANSCODER_EDP &&
>>>>    	    (pipe == PIPE_B || pipe == PIPE_C))
>>>> -		intel_de_write(display, TRANS_VTOTAL(display, pipe),
>>>> -			       VACTIVE(crtc_vdisplay - 1) |
>>>> -			       VTOTAL(crtc_vtotal - 1));
>>>> +		intel_crtc_set_vtotal(display, (enum transcoder)pipe,
>>>> +				      crtc_vdisplay, crtc_vtotal);
>>>>    }
>>>>    
>>>>    static void intel_set_transcoder_timings_lrr(const struct intel_crtc_state *crtc_state)
>>>> @@ -2766,9 +2773,7 @@ static void intel_set_transcoder_timings_lrr(const struct intel_crtc_state *crtc
>>>>    	 * The double buffer latch point for TRANS_VTOTAL
>>>>    	 * is the transcoder's undelayed vblank.
>>>>    	 */
>>>> -	intel_de_write(display, TRANS_VTOTAL(display, cpu_transcoder),
>>>> -		       VACTIVE(crtc_vdisplay - 1) |
>>>> -		       VTOTAL(crtc_vtotal - 1));
>>>> +	intel_crtc_set_vtotal(display, cpu_transcoder, crtc_vdisplay, crtc_vtotal);
>>> Not really a fan of special casing this that much. I think we should
>>> probably handle it the same way we deal with the VBLANK_START vs.
>>> TRANS_SET_CONTEXT_LATENCY.
>> Hmm I can do away with the helper, and avoid having VTOTAL.Vtotal bits
>> set for specific cases in intel_vrr_set_transcoder_{timings, timings_lrr}.
>>> The readount should perhaps just be handled in intel_vrr_get_config().
>> I can try this out.
>>
>>
>>> But I think we'll need somehting like transcoder_has_vrr() to exclude
>>> the DSI transcoders in a consistent way.
>> If I understand correctly you mean that wherever we are avoiding VRR
>> related register read/write for DSI, use trans_has_vrr() instead of
>> !transcoder_is_dsi(),
>>
>> with trans_has_vrr having call to transcoder_is_dsi()?
> Yeah something like that.
>
>> Will perhaps add this as a separate patch.
> These two last patches aren't needed to get this stuff actually
> working right? Or is the GOP leaving TRANS_VOTAL.vtotal unset?
> So yeah, if not needed right now probably best to leave this
> stuff for a seaprate series.

Yes we can have a separate series for the last one.

though, I have sent new revision, we can get the patches-1-14 merge as 
suggested.

Thanks Ville!

Regards,

Ankit

>