Some nitpicks below
On Tue, 2019-08-20 at 15:11 -0400, David Francis wrote:
We were using drm helpers to convert a timing into its bandwidth, its bandwidth into pbn, and its pbn into timeslots
These helpers -Did not take DSC timings into account -Used the link rate and lane count of the link's aux device, which are not the same as the link's current cap -Did not take FEC into account (FEC reduces the PBN per timeslot)
For converting timing into PBN, add a new function drm_dp_calc_pbn_mode_dsc that handles the DSC case
For converting PBN into time slots, amdgpu doesn't use the 'correct' atomic method (drm_dp_atomic_find_vcpi_slots), so don't add a new helper to cover our approach. Use the same means of calculating pbn per time slot as the DSC code.
v2: Add drm helper for clock to pbn conversion
Cc: Jerry Zuo Jerry.Zuo@amd.com Cc: Nicholas Kazlauskas nicholas.kazlauskas@amd.com Signed-off-by: David Francis David.Francis@amd.com
.../amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 18 +++++--- drivers/gpu/drm/drm_dp_mst_topology.c | 41 +++++++++++++++++++ include/drm/drm_dp_mst_helper.h | 2 +- 3 files changed, 54 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c index 5f2c315b18ba..dfa99e0d6e64 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c @@ -189,8 +189,8 @@ bool dm_helpers_dp_mst_write_payload_allocation_table( int slots = 0; bool ret; int clock;
- int bpp = 0; int pbn = 0;
int pbn_per_timeslot, bpp = 0;
aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
@@ -208,7 +208,6 @@ bool dm_helpers_dp_mst_write_payload_allocation_table( clock = stream->timing.pix_clk_100hz / 10;
switch (stream->timing.display_color_depth) {
- case COLOR_DEPTH_666: bpp = 6; break;
@@ -234,11 +233,18 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
bpp = bpp * 3;
/* TODO need to know link rate */pbn = drm_dp_calc_pbn_mode(clock, bpp);+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
if (stream->timing.flags.DSC)pbn = drm_dp_calc_pbn_mode_dsc(clock,stream-timing.dsc_cfg.bits_per_pixel);
else+#endif
pbn = drm_dp_calc_pbn_mode(clock, bpp);
slots = drm_dp_find_vcpi_slots(mst_mgr, pbn);
/* Convert kilobits per second / 64 (for 64 timeslots) to pbn(54/64 megabytes per second) */
pbn_per_timeslot = dc_link_bandwidth_kbps(stream->link, dc_link_get_link_cap(stream-link)) / (8 * 1000 * 54);
slots = DIV_ROUND_UP(pbn, pbn_per_timeslot);ret = drm_dp_mst_allocate_vcpi(mst_mgr, mst_port, pbn, slots);
if (!ret)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 398e7314ea8b..d789b7af7dbf 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3588,6 +3588,47 @@ static int test_calc_pbn_mode(void) return 0; }
+/**
- drm_dp_calc_pbn_mode_dsc() - Calculate the PBN for a mode with DSC
enabled.
- @clock: dot clock for the mode
- @dsc_bpp: dsc bits per pixel x16 (e.g. dsc_bpp = 136 is 8.5 bpp)
- This uses the formula in the spec to calculate the PBN value for a mode,
- given that the mode is using DSC
You should use the proper kdoc formatting for documenting return values (not all of the DP MST code does this currently, but that's a bug I haven't taken the time to fix :):
/* * foo_bar() - foo the bar * * foos the bar, guaranteed * Returns: * Some magic number */
- */
+int drm_dp_calc_pbn_mode_dsc(int clock, int dsc_bpp) +{
- u64 kbps;
- s64 peak_kbps;
- u32 numerator;
- u32 denominator;
- kbps = clock * dsc_bpp;
- /*
* margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006* The unit of 54/64Mbytes/sec is an arbitrary unit chosen based on* common multiplier to render an integer PBN for all link rate/lane* counts combinations* calculate* peak_kbps *= (1/16) bppx16 to bpp* peak_kbps *= (1006/1000)* peak_kbps *= (64/54)* peak_kbps *= 8 convert to bytes** Divide numerator and denominator by 16 to avoid overflow*/- numerator = 64 * 1006 / 16;
- denominator = 54 * 8 * 1000 * 1000;
- kbps *= numerator;
- peak_kbps = drm_fixp_from_fraction(kbps, denominator);
- return drm_fixp2int_ceil(peak_kbps);
+} +EXPORT_SYMBOL(drm_dp_calc_pbn_mode_dsc);
/* we want to kick the TX after we've ack the up/down IRQs. */ static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr) { diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h index 2ba6253ea6d3..ddb518f2157a 100644 --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -611,7 +611,7 @@ struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_
int drm_dp_calc_pbn_mode(int clock, int bpp);
+int drm_dp_calc_pbn_mode_dsc(int clock, int dsc_bpp);
bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, int pbn, int slots);