diff options
| 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.c | |
| 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.c')
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_display.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c index b51d1ceb8739..ce05e805b08f 100644 --- a/drivers/gpu/drm/i915/display/intel_display.c +++ b/drivers/gpu/drm/i915/display/intel_display.c @@ -7261,7 +7261,7 @@ retry: pipe_config->fdi_lanes = lane; intel_link_compute_m_n(pipe_config->pipe_bpp, lane, fdi_dotclock, - link_bw, &pipe_config->fdi_m_n, false); + link_bw, &pipe_config->fdi_m_n, false, false); ret = ironlake_check_fdi_lanes(dev, intel_crtc->pipe, pipe_config); if (ret == -EDEADLK) @@ -7508,11 +7508,15 @@ void intel_link_compute_m_n(u16 bits_per_pixel, int nlanes, int pixel_clock, int link_clock, struct intel_link_m_n *m_n, - bool constant_n) + bool constant_n, bool fec_enable) { - m_n->tu = 64; + u32 data_clock = bits_per_pixel * pixel_clock; + + if (fec_enable) + data_clock = intel_dp_mode_to_fec_clock(data_clock); - compute_m_n(bits_per_pixel * pixel_clock, + m_n->tu = 64; + compute_m_n(data_clock, link_clock * nlanes * 8, &m_n->gmch_m, &m_n->gmch_n, constant_n); |