The patch below does not apply to the 5.0-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 21635d7311734d2d1b177f8a95e2f9386174b76d Mon Sep 17 00:00:00 2001

From: Jani Nikula jani.nikula@intel.com Date: Fri, 5 Apr 2019 10:52:20 +0300 Subject: [PATCH] drm/i915/dp: revert back to max link rate and lane count on eDP MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

Commit 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config fast and narrow") started to optize the eDP 1.4+ link config, both per spec and as preparation for display stream compression support.

Sadly, we again face panels that flat out fail with parameters they claim to support. Revert, and go back to the drawing board.

v2: Actually revert to max params instead of just wide-and-slow.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109959 Fixes: 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config fast and narrow") Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Manasi Navare manasi.d.navare@intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Matt Atwood matthew.s.atwood@intel.com Cc: "Lee, Shawn C" shawn.c.lee@intel.com Cc: Dave Airlie airlied@gmail.com Cc: intel-gfx@lists.freedesktop.org Cc: stable@vger.kernel.org # v5.0+ Reviewed-by: Rodrigo Vivi rodrigo.vivi@intel.com Reviewed-by: Manasi Navare manasi.d.navare@intel.com Tested-by: Albert Astals Cid aacid@kde.org # v5.0 backport Tested-by: Emanuele Panigati ilpanich@gmail.com # v5.0 backport Tested-by: Matteo Iervasi matteoiervasi@gmail.com # v5.0 backport Signed-off-by: Jani Nikula jani.nikula@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20190405075220.9815-1-jani.nik... (cherry picked from commit f11cb1c19ad0563b3c1ea5eb16a6bac0e401f428) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index cf709835fb9a..8891f29a8c7f 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -1859,42 +1859,6 @@ intel_dp_compute_link_config_wide(struct intel_dp *intel_dp, return -EINVAL; }

-/* Optimize link config in order: max bpp, min lanes, min clock */ -static int -intel_dp_compute_link_config_fast(struct intel_dp *intel_dp, - struct intel_crtc_state *pipe_config, - const struct link_config_limits *limits) -{ - struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode; - int bpp, clock, lane_count; - int mode_rate, link_clock, link_avail; - - for (bpp = limits->max_bpp; bpp >= limits->min_bpp; bpp -= 2 * 3) { - mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock, - bpp); - - for (lane_count = limits->min_lane_count; - lane_count <= limits->max_lane_count; - lane_count <<= 1) { - for (clock = limits->min_clock; clock <= limits->max_clock; clock++) { - link_clock = intel_dp->common_rates[clock]; - link_avail = intel_dp_max_data_rate(link_clock, - lane_count); - - if (mode_rate <= link_avail) { - pipe_config->lane_count = lane_count; - pipe_config->pipe_bpp = bpp; - pipe_config->port_clock = link_clock; - - return 0; - } - } - } - } - - return -EINVAL; -} - static int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 dsc_max_bpc) { int i, num_bpc; @@ -2031,15 +1995,13 @@ intel_dp_compute_link_config(struct intel_encoder *encoder, limits.min_bpp = 6 * 3; limits.max_bpp = intel_dp_compute_bpp(intel_dp, pipe_config);

- if (intel_dp_is_edp(intel_dp) && intel_dp->edp_dpcd[0] < DP_EDP_14) { + if (intel_dp_is_edp(intel_dp)) { /* * Use the maximum clock and number of lanes the eDP panel - * advertizes being capable of. The eDP 1.3 and earlier panels - * are generally designed to support only a single clock and - * lane configuration, and typically these values correspond to - * the native resolution of the panel. With eDP 1.4 rate select - * and DSC, this is decreasingly the case, and we need to be - * able to select less than maximum link config. + * advertizes being capable of. The panels are generally + * designed to support only a single clock and lane + * configuration, and typically these values correspond to the + * native resolution of the panel. */ limits.min_lane_count = limits.max_lane_count; limits.min_clock = limits.max_clock; @@ -2053,22 +2015,11 @@ intel_dp_compute_link_config(struct intel_encoder *encoder, intel_dp->common_rates[limits.max_clock], limits.max_bpp, adjusted_mode->crtc_clock);

- if (intel_dp_is_edp(intel_dp)) - /* - * Optimize for fast and narrow. eDP 1.3 section 3.3 and eDP 1.4 - * section A.1: "It is recommended that the minimum number of - * lanes be used, using the minimum link rate allowed for that - * lane configuration." - * - * Note that we use the max clock and lane count for eDP 1.3 and - * earlier, and fast vs. wide is irrelevant. - */ - ret = intel_dp_compute_link_config_fast(intel_dp, pipe_config, - &limits); - else - /* Optimize for slow and wide. */ - ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config, - &limits); + /* + * Optimize for slow and wide. This is the place to add alternative + * optimization policy. + */ + ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config, &limits);

/* enable compression if the mode doesn't fit available BW */ DRM_DEBUG_KMS("Force DSC en = %d\n", intel_dp->force_dsc_en);