[PATCH] drm/i915: limit eDP MSO pipe only for display version 20 and below

[Gustavo Sousa]

Hi, Luca!

Quoting Luca Coelho (2024-01-24 05:52:29-03:00)
>The pipes that can be used for eDP MSO are limited to pipe A (and
>sometimes also pipe B) only for display version 20 and below.
>
>Modify the function that returns the pipe mask for eDP MSO so that
>these limitations only apply to version 20 and below, enabling all
>pipes otherwise.
>
>Bspec: 68923
>Cc: Jani Nikula <jani.nikula at intel.com>
>Cc: James Ausmus <james.ausmus at intel.com>
>Signed-off-by: Luca Coelho <luciano.coelho at intel.com>
>---
> drivers/gpu/drm/i915/display/intel_ddi.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
>index 922194b957be..5c99ae148213 100644
>--- a/drivers/gpu/drm/i915/display/intel_ddi.c
>+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
>@@ -2336,13 +2336,18 @@ static void intel_ddi_power_up_lanes(struct intel_encoder *encoder,
>         }
> }
> 
>-/* Splitter enable for eDP MSO is limited to certain pipes. */
>+/*
>+ * Splitter enable for eDP MSO is limited to certain pipes, on certain
>+ * platforms.
>+ */
> static u8 intel_ddi_splitter_pipe_mask(struct drm_i915_private *i915)
> {
>         if (IS_ALDERLAKE_P(i915))

Looks like Xe_LPD+ (MTL's display) and Xe2_LPD (LNL's display) both support both
pipes A and B. For Xe_LPD+ we have that info in BSpec 55473 and for Xe2_LPD, in
BSpec 68923. So, I think we could:

  a. OR the condition above with IS_DISPLAY_IP_RANGE(i915, IP_VER(14, 0),
     IP_VER(20, 0)), and
  b. And make the "else if" below be about display versions below 14.

With those additions,

Reviewed-by: Gustavo Sousa <gustavo.sousa at intel.com>

--
Gustavo Sousa

>                 return BIT(PIPE_A) | BIT(PIPE_B);
>-        else
>+        else if (DISPLAY_VER(i915) <= 20)
>                 return BIT(PIPE_A);
>+
>+        return ~0;
> }
> 
> static void intel_ddi_mso_get_config(struct intel_encoder *encoder,
>-- 
>2.39.2
>