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

[Nautiyal, Ankit K]

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.nauti...@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