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| author | Maarten Lankhorst <maarten.lankhorst@linux.intel.com> | 2019-09-25 10:21:09 +0200 |
|---|---|---|
| committer | Rodrigo Vivi <rodrigo.vivi@intel.com> | 2019-10-02 22:20:22 -0700 |
| commit | cffb4c3ea37248c4fc2f4ce747e5c24af88aec76 (patch) | |
| tree | 5de9c6b47929b77d673271b253125d8a5f1a3cc5 /drivers/gpu/drm/i915/display/intel_display.h | |
| parent | 54ecb8f7028c5eb3d740bb82b0f1d90f2df63c5c (diff) | |
drm/i915/dp: Fix dsc bpp calculations, v5.
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 <maarten.lankhorst@linux.intel.com>
Fixes: d9218c8f6cf4 ("drm/i915/dp: Add helpers for Compressed BPP and Slice Count for DSC")
Cc: <stable@vger.kernel.org> # v5.0+
Cc: Manasi Navare <manasi.d.navare@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190925082110.17439-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
(cherry picked from commit ed06efb801bd291e935238d3fba46fa03d098f0e)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Diffstat (limited to 'drivers/gpu/drm/i915/display/intel_display.h')
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_display.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h index e57e6969051d..01fa87ad3270 100644 --- a/drivers/gpu/drm/i915/display/intel_display.h +++ b/drivers/gpu/drm/i915/display/intel_display.h @@ -414,7 +414,7 @@ enum phy_fia { void intel_link_compute_m_n(u16 bpp, int nlanes, int pixel_clock, int link_clock, struct intel_link_m_n *m_n, - bool constant_n); + bool constant_n, bool fec_enable); bool is_ccs_modifier(u64 modifier); void lpt_disable_clkout_dp(struct drm_i915_private *dev_priv); u32 intel_plane_fb_max_stride(struct drm_i915_private *dev_priv, |