From cffb4c3ea37248c4fc2f4ce747e5c24af88aec76 Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Wed, 25 Sep 2019 10:21:09 +0200 Subject: drm/i915/dp: Fix dsc bpp calculations, v5. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There was a integer wraparound when mode_clock became too high, and we didn't correct for the FEC overhead factor when dividing, with the calculations breaking at HBR3. As a result our calculated bpp was way too high, and the link width limitation never came into effect. Print out the resulting bpp calcululations as a sanity check, just in case we ever have to debug it later on again. We also used the wrong factor for FEC. While bspec mentions 2.4%, all the calculations use 1/0.972261, and the same ratio should be applied to data M/N as well, so use it there when FEC is enabled. This fixes the FIFO underrun we are seeing with FEC enabled. Changes since v2: - Handle fec_enable in intel_link_compute_m_n, so only data M/N is adjusted. (Ville) - Fix initial hardware readout for FEC. (Ville) Changes since v3: - Remove bogus fec_to_mode_clock. (Ville) Changes since v4: - Use the correct register for icl. (Ville) - Split hw readout to a separate patch. Signed-off-by: Maarten Lankhorst Fixes: d9218c8f6cf4 ("drm/i915/dp: Add helpers for Compressed BPP and Slice Count for DSC") Cc: # v5.0+ Cc: Manasi Navare Link: https://patchwork.freedesktop.org/patch/msgid/20190925082110.17439-1-maarten.lankhorst@linux.intel.com Reviewed-by: Ville Syrjälä (cherry picked from commit ed06efb801bd291e935238d3fba46fa03d098f0e) Signed-off-by: Rodrigo Vivi --- drivers/gpu/drm/i915/display/intel_dp.h | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'drivers/gpu/drm/i915/display/intel_dp.h') diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h index 657bbb1f5ed0..00981fb9414b 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.h +++ b/drivers/gpu/drm/i915/display/intel_dp.h @@ -102,10 +102,6 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp); bool intel_dp_source_supports_hbr3(struct intel_dp *intel_dp); bool intel_dp_get_link_status(struct intel_dp *intel_dp, u8 *link_status); -u16 intel_dp_dsc_get_output_bpp(int link_clock, u8 lane_count, - int mode_clock, int mode_hdisplay); -u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp, int mode_clock, - int mode_hdisplay); bool intel_dp_read_dpcd(struct intel_dp *intel_dp); bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp); @@ -118,4 +114,6 @@ static inline unsigned int intel_dp_unused_lane_mask(int lane_count) return ~((1 << lane_count) - 1) & 0xf; } +u32 intel_dp_mode_to_fec_clock(u32 mode_clock); + #endif /* __INTEL_DP_H__ */ -- cgit v1.2.3