diff options
| author | David Francis <David.Francis@amd.com> | 2019-08-21 10:33:26 -0400 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2020-01-09 18:07:46 -0500 |
| commit | dc48529fb14ee8450705c00d91f4dcc155e1c2cb (patch) | |
| tree | 75da55ea5145d34d4e7a0e897a8226921931a8ff /drivers/gpu/drm/drm_dp_mst_topology.c | |
| parent | 0f899fd466b693a129b16994c1b2b4db2fcde4a4 (diff) | |
drm/dp_mst: Add PBN calculation for DSC modes
With DSC, bpp can be fractional in multiples of 1/16.
Change drm_dp_calc_pbn_mode to reflect this, adding a new
parameter bool dsc. When this parameter is true, treat the
bpp parameter as having units not of bits per pixel, but
1/16 of a bit per pixel
v2: Don't add separate function for this
v3: In the equation divide bpp by 16 as it is expected
not to leave any remainder
v4: Added DSC test parameters for selftest
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: David Francis <David.Francis@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'drivers/gpu/drm/drm_dp_mst_topology.c')
| -rw-r--r-- | drivers/gpu/drm/drm_dp_mst_topology.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index e68d23043973..2443532341d0 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -4415,10 +4415,11 @@ EXPORT_SYMBOL(drm_dp_check_act_status); * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode. * @clock: dot clock for the mode * @bpp: bpp for the mode. + * @dsc: DSC mode. If true, bpp has units of 1/16 of a bit per pixel * * This uses the formula in the spec to calculate the PBN value for a mode. */ -int drm_dp_calc_pbn_mode(int clock, int bpp) +int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc) { /* * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006 @@ -4429,7 +4430,16 @@ int drm_dp_calc_pbn_mode(int clock, int bpp) * peak_kbps *= (1006/1000) * peak_kbps *= (64/54) * peak_kbps *= 8 convert to bytes + * + * If the bpp is in units of 1/16, further divide by 16. Put this + * factor in the numerator rather than the denominator to avoid + * integer overflow */ + + if (dsc) + return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006), + 8 * 54 * 1000 * 1000); + return DIV_ROUND_UP_ULL(mul_u32_u32(clock * bpp, 64 * 1006), 8 * 54 * 1000 * 1000); } |