On Thu, Mar 05, 2026 at 05:50:10PM +0530, Animesh Manna wrote:
> Unused bandwidth can be used by external display agents for Panel Replay
> enabled DP panel during idleness with link on. Enable source to replace
> dummy data from the display with data from another agent by programming
> TRANS_DP2_CTL [Panel Replay Tunneling Enable].
>
> v2:
> - Enable pr bw optimization along with panel replay enable. [Jani]
>
> v3:
> - Write TRANS_DP2_CTL once for both bw optimization and panel replay
> enable. [Jani]
>
> v4:
> - Read DPCD once in init() and store in panel_replay_caps. [Jouni]
>
> v5:
> - Avoid reading DPCD for edp. [Jouni]
> - Use drm_dp_dpcd_read_byte() and some cosmetic changes. [Jani]
>
> Bspec: 68920
> Reviewed-by: Arun R Murthy <[email protected]>
> Signed-off-by: Animesh Manna <[email protected]>
> ---
> .../gpu/drm/i915/display/intel_display_regs.h | 1 +
> .../drm/i915/display/intel_display_types.h | 1 +
> drivers/gpu/drm/i915/display/intel_dp.c | 1 +
> drivers/gpu/drm/i915/display/intel_psr.c | 35 +++++++++++++++++--
> 4 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_regs.h
> b/drivers/gpu/drm/i915/display/intel_display_regs.h
> index 5838338f495a..0a641daf22c6 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_regs.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_regs.h
> @@ -2269,6 +2269,7 @@
> #define TRANS_DP2_CTL(trans) _MMIO_TRANS(trans,
> _TRANS_DP2_CTL_A, _TRANS_DP2_CTL_B)
> #define TRANS_DP2_128B132B_CHANNEL_CODING REG_BIT(31)
> #define TRANS_DP2_PANEL_REPLAY_ENABLE REG_BIT(30)
> +#define TRANS_DP2_PR_TUNNELING_ENABLE REG_BIT(26)
> #define TRANS_DP2_DEBUG_ENABLE REG_BIT(23)
>
> #define _TRANS_DP2_VFREQHIGH_A 0x600a4
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 7adfb4169e25..a291665808cc 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -576,6 +576,7 @@ struct intel_connector {
>
> bool support;
> bool su_support;
> + bool optimization_support;
> enum intel_panel_replay_dsc_support dsc_support;
>
> u16 su_w_granularity;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index fcf478fbf8cd..7758213c070e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -6250,6 +6250,7 @@ intel_dp_detect(struct drm_connector *_connector,
> intel_dp->psr.sink_panel_replay_support = false;
> connector->dp.panel_replay_caps.support = false;
> connector->dp.panel_replay_caps.su_support = false;
> + connector->dp.panel_replay_caps.optimization_support = false;
> connector->dp.panel_replay_caps.dsc_support =
> INTEL_DP_PANEL_REPLAY_DSC_NOT_SUPPORTED;
>
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> b/drivers/gpu/drm/i915/display/intel_psr.c
> index 5bea2eda744b..27ba96ede8e2 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -43,6 +43,7 @@
> #include "intel_dmc.h"
> #include "intel_dp.h"
> #include "intel_dp_aux.h"
> +#include "intel_dp_tunnel.h"
> #include "intel_dsb.h"
> #include "intel_frontbuffer.h"
> #include "intel_hdmi.h"
> @@ -603,6 +604,7 @@ static void _panel_replay_init_dpcd(struct intel_dp
> *intel_dp, struct intel_conn
> {
> struct intel_display *display = to_intel_display(intel_dp);
> int ret;
> + u8 val;
>
> /* TODO: Enable Panel Replay on MST once it's properly implemented. */
> if (intel_dp->mst_detect == DRM_DP_MST)
> @@ -650,6 +652,15 @@ static void _panel_replay_init_dpcd(struct intel_dp
> *intel_dp, struct intel_conn
> connector->dp.panel_replay_caps.su_support ?
> "selective_update " : "",
>
> panel_replay_dsc_support_str(connector->dp.panel_replay_caps.dsc_support));
> +
> + if (intel_dp_is_edp(intel_dp))
> + return;
> +
> + /* Rest is for DP only */
> +
> + drm_dp_dpcd_read_byte(&intel_dp->aux, DP_TUNNELING_CAPABILITIES, &val);
> + connector->dp.panel_replay_caps.optimization_support = val &
> + DP_PANEL_REPLAY_OPTIMIZATION_SUPPORT;
The above DPCD register is read already by drm_dp_tunnel_detect(), so I
think the proper way is to extend the corresponding interface defined in
drm_dp_tunnel.c to query the Panel Replay optimization capability.
> }
>
> static void _psr_init_dpcd(struct intel_dp *intel_dp, struct intel_connector
> *connector)
> @@ -1022,11 +1033,29 @@ static u8 frames_before_su_entry(struct intel_dp
> *intel_dp)
> return frames_before_su_entry;
> }
>
> +static bool intel_psr_allow_pr_bw_optimization(struct intel_dp *intel_dp)
> +{
> + struct intel_display *display = to_intel_display(intel_dp);
> + struct intel_connector *connector = intel_dp->attached_connector;
> +
> + if (DISPLAY_VER(display) < 35)
> + return false;
> +
> + if (!intel_dp_tunnel_bw_alloc_is_enabled(intel_dp))
> + return false;
> +
> + if (!connector->dp.panel_replay_caps.optimization_support)
> + return false;
> +
> + return true;
> +}
> +
> static void dg2_activate_panel_replay(struct intel_dp *intel_dp)
> {
> struct intel_display *display = to_intel_display(intel_dp);
> struct intel_psr *psr = &intel_dp->psr;
> enum transcoder cpu_transcoder = intel_dp->psr.transcoder;
> + u32 dp2_ctl_val = TRANS_DP2_PANEL_REPLAY_ENABLE;
>
> if (intel_dp_is_edp(intel_dp) && psr->sel_update_enabled) {
> u32 val = psr->su_region_et_enabled ?
> @@ -1039,12 +1068,14 @@ static void dg2_activate_panel_replay(struct intel_dp
> *intel_dp)
> val);
> }
>
> + if (!intel_dp_is_edp(intel_dp) &&
> intel_psr_allow_pr_bw_optimization(intel_dp))
> + dp2_ctl_val |= TRANS_DP2_PR_TUNNELING_ENABLE;
> +
> intel_de_rmw(display,
> PSR2_MAN_TRK_CTL(display, intel_dp->psr.transcoder),
> 0, ADLP_PSR2_MAN_TRK_CTL_SF_CONTINUOS_FULL_FRAME);
>
> - intel_de_rmw(display, TRANS_DP2_CTL(intel_dp->psr.transcoder), 0,
> - TRANS_DP2_PANEL_REPLAY_ENABLE);
> + intel_de_rmw(display, TRANS_DP2_CTL(intel_dp->psr.transcoder), 0,
> dp2_ctl_val);
> }
>
> static void hsw_activate_psr2(struct intel_dp *intel_dp)
> --
> 2.29.0
>
