Re: [Intel-gfx] [PATCH 4/4] drm/i915/dp: Ignore max_requested_bpc if its too low for DSC

[Nautiyal, Ankit K]

On 11/9/2023 12:19 PM, Kandpal, Suraj wrote:

-----Original Message-----
From: Intel-gfx <intel-gfx-boun...@lists.freedesktop.org> On Behalf Of Ankit
Nautiyal
Sent: Tuesday, November 7, 2023 9:48 AM
To: intel-gfx@lists.freedesktop.org
Cc: Nikula, Jani <jani.nik...@intel.com>
Subject: [Intel-gfx] [PATCH 4/4] drm/i915/dp: Ignore max_requested_bpc if its
too low for DSC

At the moment, while choosing the input bpc for DSC, we take into account the
max_requested_bpc property. This creates a problem, if the
max_requested_bpc is lower than the minimum bpc required by source with
DSC.

So consider max_requested_bpc if its within the limits that we can support with
DSC.

Signed-off-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>
---
  drivers/gpu/drm/i915/display/intel_dp.c | 22 ++++++++++++++++++----
  1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
b/drivers/gpu/drm/i915/display/intel_dp.c
index abc718f1a878..ea4c42a5705e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1578,6 +1578,16 @@ u8 intel_dp_dsc_max_src_input_bpc(struct
drm_i915_private *i915)
        return 12;
  }

+static int
+intel_dp_dsc_limit_max_bpc(int max_requested_bpc, int src_dsc_max_bpc,
+int src_dsc_min_bpc) {
+       /* Consider max_requested_bpc only if src can support it with DSC */
+       if (max_requested_bpc >= src_dsc_min_bpc)
+               return min(src_dsc_max_bpc, max_requested_bpc);
+
+       return src_dsc_max_bpc;
+}
+
  int intel_dp_dsc_compute_max_bpp(const struct intel_connector *connector,
                                 u8 max_req_bpc)
  {
@@ -1591,7 +1601,8 @@ int intel_dp_dsc_compute_max_bpp(const struct
intel_connector *connector,
        if (!dsc_max_bpc)
                return dsc_max_bpc;

-       dsc_max_bpc = min_t(u8, dsc_max_bpc, max_req_bpc);
+       dsc_max_bpc = intel_dp_dsc_limit_max_bpc(max_req_bpc,
dsc_max_bpc,
+
intel_dp_dsc_min_src_input_bpc(i915));

        num_bpc = drm_dp_dsc_sink_supported_input_bpcs(connector-
dp.dsc_dpcd,
                                                       dsc_bpc);
@@ -1959,8 +1970,11 @@ bool is_dsc_pipe_bpp_sufficient(struct
drm_i915_private *i915,  {
        u8 dsc_max_bpc, dsc_min_bpc, dsc_max_pipe_bpp,
dsc_min_pipe_bpp;

-       dsc_max_bpc = min(intel_dp_dsc_max_src_input_bpc(i915),
conn_state->max_requested_bpc);
        dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
+       dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
Seems like this change could have been a part of the previous patch.

Hi Suraj,

Previous patch was only using helpers to get src_min_max dsc bpc for dp 
mst case.

Regards,

Ankit



Regards,
Suraj Kandpal
+
+       dsc_max_bpc = intel_dp_dsc_limit_max_bpc(conn_state-
max_requested_bpc,
+                                                dsc_max_bpc, dsc_min_bpc);

        dsc_max_pipe_bpp = min(dsc_max_bpc * 3, limits->pipe.max_bpp);
        dsc_min_pipe_bpp = max(dsc_min_bpc * 3, limits->pipe.min_bpp);
@@ -2020,14 +2034,14 @@ static int intel_dp_dsc_compute_pipe_bpp(struct
intel_dp *intel_dp,
                }
        }

+       dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
        dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
        if (!dsc_max_bpc)
                return -EINVAL;

-       dsc_max_bpc = min_t(u8, dsc_max_bpc, max_req_bpc);
+       dsc_max_bpc = intel_dp_dsc_limit_max_bpc(max_req_bpc,
dsc_max_bpc,
+dsc_min_bpc);
        dsc_max_bpp = min(dsc_max_bpc * 3, limits->pipe.max_bpp);

-       dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
        dsc_min_bpp = max(dsc_min_bpc * 3, limits->pipe.min_bpp);

        /*
--
2.40.1