From 1ebc27248ea0b81f0023ca28894ac40183b86b7c Mon Sep 17 00:00:00 2001 From: Dibin Moolakadan Subrahmanian Date: Thu, 7 Aug 2025 13:54:02 +0530 Subject: [PATCH] drm/i915/display: Optimize panel power-on wait time The current wait_panel_status() uses intel_de_wait(), which internally on Xe platforms calls xe_mmio_wait32(). xe_mmio_wait32() increases poll interval exponentially. This exponential poll interval increase causes unnessory delays during resume or power-on when the panel becomes ready earlier, but polling is delayed due to backoff. Replace intel_de_wait() with read_poll_timeout() + intel_de_read() to actively poll the register at a fixed 10ms interval up to a 5 second timeout. This allows poll to exit early when panel is ready. Changes in v2: Replaced two-phase intel_de_wait() with read_poll_timeout() + intel_de_read() Changes in v3: - Add poll_interval_ms argument 'wait_panel_status' function. - Modify 'wait_panel_status' callers with proper poll interval Changes in v4: - Change 'wait_panel_off' poll interval to 10ms Changes in v5: - Dropped poll_interval_ms parameter,use fixed polling interval of 10ms (Jani Nikula) Changes in v6: - Removed goto in error path Signed-off-by: Dibin Moolakadan Subrahmanian Link: https://lore.kernel.org/r/20250807082402.79018-1-dibin.moolakadan.subrahmanian@intel.com Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/display/intel_pps.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_pps.c b/drivers/gpu/drm/i915/display/intel_pps.c index b64d0b30f5b1..b84eb43bd2d0 100644 --- a/drivers/gpu/drm/i915/display/intel_pps.c +++ b/drivers/gpu/drm/i915/display/intel_pps.c @@ -4,6 +4,7 @@ */ #include +#include #include @@ -608,6 +609,8 @@ static void wait_panel_status(struct intel_dp *intel_dp, struct intel_display *display = to_intel_display(intel_dp); struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp); i915_reg_t pp_stat_reg, pp_ctrl_reg; + int ret; + u32 val; lockdep_assert_held(&display->pps.mutex); @@ -624,13 +627,20 @@ static void wait_panel_status(struct intel_dp *intel_dp, intel_de_read(display, pp_stat_reg), intel_de_read(display, pp_ctrl_reg)); - if (intel_de_wait(display, pp_stat_reg, mask, value, 5000)) + ret = read_poll_timeout(intel_de_read, val, + (val & mask) == value, + 10 * 1000, 5000 * 1000, true, + display, pp_stat_reg); + + if (ret) { drm_err(display->drm, "[ENCODER:%d:%s] %s panel status timeout: PP_STATUS: 0x%08x PP_CONTROL: 0x%08x\n", dig_port->base.base.base.id, dig_port->base.base.name, pps_name(intel_dp), intel_de_read(display, pp_stat_reg), intel_de_read(display, pp_ctrl_reg)); + return; + } drm_dbg_kms(display->drm, "Wait complete\n"); } -- 2.51.0