Atm, a DP DSC video mode's required BW vs. the available BW is
determined by calculating the maximum compressed BPP value allowed by
the available BW. Doing that using a closed-form formula as it's done
atm (vs. an iterative way) is problematic, since the overhead of the
required BW itself depends on the BPP value being calculated. Instead of
that calculate the required BW for the minimum compressed BPP value
supported both by the source and the sink and check this BW against the
available BW. This change also aligns the BW calculation during mode
validation with how this is done during state computation, calculating
the required effective data rate with the corresponding BW overhead.
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251222153547.713360-14-imre.deak@intel.com
Add intel_dp_mode_valid_with_dsc() and call this for an SST/MST mode
validation to prepare for a follow-up change using a way to verify the
mode's required BW the same way this is done elsewhere during state
computation (which in turn depends on the mode's effective data rate
with the corresponding BW overhead).
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251222153547.713360-13-imre.deak@intel.com
Use intel_dp_effective_data_rate() to calculate the required link BW for
eDP, DP-SST and MST links. This ensures that the BW is calculated the
same way for all DP output types, during mode validation as well as
during state computation. This approach also allows for accounting with
BW overheads due to the SSC, DSC, FEC being enabled on a link, as well
as due to the MST symbol alignment on the link. Accounting for these
overheads will be added by follow-up changes.
This way also computes the stream BW on a UHBR link correctly, using the
corresponding symbol size to effective data size ratio (i.e. ~97% link
BW utilization for UHBR vs. only ~80% for non-UHBR).
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251215192357.172201-9-imre.deak@intel.com
Convert intel_dp_output_bpp() and intel_dp_mode_min_output_bpp() to
return an x16 fixed point bpp value, as this value will be always the
link BPP (either compressed or uncompressed) tracked in the same x16
fixed point format.
While at it rename
intel_dp_output_bpp() to intel_dp_output_format_link_bpp_x16() and
intel_dp_mode_min_output_bpp() to intel_dp_mode_min_link_bpp_x16() to
better reflect that these functions return an x16 link BPP value
specific to a particular output format or mode.
Also rename intel_dp_output_bpp()'s bpp parameter to pipe_bpp, to
clarify which kind of (pipe vs. link) BPP the parameter is.
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251215192357.172201-5-imre.deak@intel.com
Add a helper to compute vblank time needed for transmitting specific
DisplayPort SDPs like PPS, GAMUT_METADATA, and VSC_EXT. Latency is
based on line count per packet type.
This will be used to ensure adequate guardband when features like DSC/HDR
are enabled.
v2: Correct the lines required for PPS SDP. (Jouni)
Bspec: 70151
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20251017123504.2247954-3-ankit.k.nautiyal@intel.com
Export the helper function to determine if FEC is required on a non-UHBR
(8b10b) SST or MST link. A follow up change will take this into use for
MST as well.
While at it determine the output type from the CRTC state, which allows
dropping the intel_dp argument. Also make the function return the
required FEC state, instead of setting this in the CRTC state, which
allows only querying this requirement, without changing the state.
Also rename the function to intel_dp_needs_8b10b_fec(), to clarify that
the function determines if FEC is required on an 8b10b link (on 128b132b
links FEC is always enabled by the HW implicitly, so the function will
return false for that case).
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20251015161934.262108-4-imre.deak@intel.com
Introduce intel_dp_compute_config_late() to handle late-stage
configuration checks for DP/eDP features. For now, it paves path for
psr_compute_config_late() to handle psr parameters that need to be
computed late.
Move the handling of psr_flag for Wa_18037818876 and setting of non-psr
pipes to intel_psr_compute_config_late() as these are the last things
to be configured for PSR features.
v2: Update dp_compute_config_late() to return int.
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com> (#v1)
Link: https://lore.kernel.org/r/20251016055415.2101347-8-ankit.k.nautiyal@intel.com
Update intel_dp_compute_config_limits() to use a minimum of
30 bits per pixel when the connector is in HDR mode
(specifically, when EOTF is SMPTE ST2084), aligning with HDR
display requirements.
To support this, the function now takes a drm_connector_state
instead of an intel_connector, and the required updates are
made in all call sites, including MST handling.
This ensures sufficient bitdepth for HDR content to avoid
banding.
If the required bandwidth for 30 bpp cannot be supported,
the driver will either fall back to DSC or reject the mode
during atomic check if DSC is not supported.
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://lore.kernel.org/r/20250730055523.2214966-3-chaitanya.kumar.borah@intel.com
The intel_dp_in_hdr_mode() helper was previously defined in
intel_dp_aux_backlight.c but is generally useful beyond that
context. Move the function to intel_dp.c and declare it in
intel_dp.h to make it accessible to other DP-related code
paths that need to check HDR metadata state.
This is a pure refactor with no functional change and
prepares for a follow-up patch that uses this helper.
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://lore.kernel.org/r/20250730055523.2214966-2-chaitanya.kumar.borah@intel.com
Reading DPCD registers has side-effects and some of these can cause a
problem for instance during link training. Based on this it's better to
avoid the probing quirk done before each DPCD register read, limiting
this to the monitor which requires it. The only known problematic
monitor is an external SST sink, so keep the quirk disabled always for
eDP and MST sinks. Reenable the quirk after a hotplug event and after
resuming from a power state without hotplug support, until the
subsequent EDID based detection.
v2: Add a helper for determining the need/setting the probing. (Jani)
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250609125556.109538-2-imre.deak@intel.com
Enable using a fractional (compressed) link bpp on MST links, if this is
supported and the link bpp is forced. Fractional link bpps will be
enabled by default as a follow-up change after testing this
functionality within a set of commonly used MST monitors and docks/hubs
which support it.
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250509180340.554867-13-imre.deak@intel.com
Adjusting the compressed bpp range min/max limits in
intel_dp_dsc_nearest_valid_bpp() is unnecessary:
- The source/sink min/max values are enforced already by the
link_config_limits::min_bpp_x16/max_bpp_x16 values computed early in
intel_dp_compute_config_link_bpp_limits().
- The fixed set of valid bpps are enforced already - for all bpps in the
min .. max range by intel_dp_dsc_valid_compressed_bpp() called from
intel_dp_mtp_tu_compute_config().
The only thing needed is limiting max compressed bpp below the
uncompressed pipe bpp, do that one thing only instead of calling
intel_dp_dsc_nearest_valid_bpp().
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250509180340.554867-7-imre.deak@intel.com
Atm TGL supports only a fixed set of valid DSC compressed bpps
(6,8,10,12,15), but this is not taken into account while looking for a
bpp in the minimum..maximum compressed bpp range.
This happened to work only by chance since atm from the above min..max
range it's always the maximum bpp that is selected, which is one of the
above valid bpps (see mst_stream_dsc_compute_link_config() ->
intel_dp_dsc_nearest_valid_bpp()). Before selecting a bpp however, the
bpp's BW requirement should be checked wrt. to the MST total link BW;
after doing that - in a follow-up change - the validity of any bpp in
the min..max range must be ensured before the bpp is selected, do that
here.
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250509180340.554867-4-imre.deak@intel.com
Atm, on an MST link in DSC mode
intel_dp_compute_config_link_bpp_limits() calculates the maximum link
bpp limit using the MST root connector's DSC capabilities. That's not
correct in general: the decompression could be performed by a branch
device downstream of the root branch device or the sink itself.
Fix the above by passing to intel_dp_compute_config_link_bpp_limits()
the actual connector being modeset, containing the correct DSC
capabilities.
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Fixes: 1c5b72daff ("drm/i915/dp: Set the DSC link limits in intel_dp_compute_config_link_bpp_limits")
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250509180340.554867-2-imre.deak@intel.com
Minimum HBlank is programmed to address jitter for high resolutions with
high refresh rates that have small Hblank, specifically where Hblank is
smaller than one MTP.
TODO: Add the min_hblank calculation for hdmi as well.
v2: move from intel_audio.c to intel_dp.c
some correction in link_bpp_x16 (Imre)
v3: min_hblank for 8b/10b MST and 128b/132b SST/MST
handle error for intel_dp_mst_dsc_get_slice_count
reset min_hblank before disabling transcoder (Imre)
v4: compute link_bpp_x16 within compute_min_hblank,
return error in case of compute failure
call compute_min_hblank() before vrr_compute_config (Imre)
v5: readout MIN_HBLAN reg for Xe3+
Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250424-hblank-v7-2-8b002f1506cc@intel.com
Forward Error Correction is required for DP if we are using DSC but
is optional for eDP.
Currently the helper intel_dp_supports_dsc checks if fec_enable is set for
DP or not. The helper is called after fec_enable is set in crtc_state.
Instead of this a better approach would be to:
first, call intel_dp_supports_dsc to check for DSC support
(along with FEC requirement for DP) and then set fec_enable for DP
(if not already set) in crtc_state.
To achieve this, remove the check for fec_enable in the helper and instead
check for FEC support for DP. With this change the helper
intel_dp_supports_dsc can be called earlier and return early if DSC is
not supported. The structure intel_dp is added to the helper to get the
FEC support for DP.
v2: Pass intel_dp to adjust_limits_for_dsc_hblank_expansion_quirk
instead of deriving it from connector. (Jani)
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217093244.3938132-2-ankit.k.nautiyal@intel.com
While updating the source OUI on the sink the driver should avoid
writing the OUI if it's already up-to-date to prevent the sink from
resetting itself in response to the update. On eDP - the only output
type where the OUI was updated so far - the driver ensured this by
comparing the current source OUI DPCD register values with the expected
Intel OUI value, skipping the update in case of a match. On some non-eDP
sinks - at least on Synaptics branch devices - this method doesn't work,
since the source OUI DPCD registers read back as all 0, even after
updating the registers.
Handle the above kind of sinks by tracking when the OUI was updated and
so should be valid, regardless of what the DPCD registers contain.
eDP sinks reset the written source OUI value when the panel power is
disabled, invalidate the OUI state accordingly.
This is required by a follow-up patch updating the source OUI for
non-eDP sink types as well.
v2: Fix setting intel_dp::oui_valid=true, if the DPCD register contains
already the expected value.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241025160259.3088727-5-imre.deak@intel.com
Make sure that a DP connector detection doesn't happen in parallel
with an ongoing modeset on the connector. The reasons for this are:
- Besides reading the capabilities, EDID etc. the detection may change
the state of the sink (via the AUX bus), for instance by setting the
LTTPR mode or the source OUI (the latter introduced by an upcoming
patch). It's better to avoid such changes affecting an onging modeset
in any way.
- During a modeset's link training any access to DPCD registers, besides
the registers used for link training should be avoided, at least in
the LTTPR non-transparent and transparent link training modes.
Such asynchronous accesses - besides connector detection - can also
happen via the AUX device node for instance, for those a parallel
modeset will have to be avoided in a similar way to the change in this
patch. (A topic for a follow-up change.)
- The source OUI written to an eDP sink is valid only while the panel
power is enabled. A modeset on eDP will enable/disable the panel power
synchronously; this should be prevented in the middle of the connector
detection, to ensure a consistent sink state (which depends on the
source OUI) for the whole duration of detection. The panel power could
still get disabled during detection after an idle period (1 sec), this
will be prevented by the next patch.
v2: (Ville)
- s/wait_for_crtc_hw_done/wait_for_connector_hw_done
- Get drm_device using an intel_display instead of drm_i915_private ptr.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241025160259.3088727-2-imre.deak@intel.com
Add a helper to compute the number of pipes required.
This will depend on whether the joiner is required or is forced through
the debugfs. If no joiner is required the helper returns 1.
v2:
-Return 1 if no joiner is required. (Ville)
-Change the suffix from joined_pipes to num_pipes. (Ville)
-Use number of pipes while calculating joined_pipe masks and
max_dotclk. (Ville)
v3: Simplify and rename the helper to intel_dp_num_joined_pipes(). Ville
v4: Remove redundant 'fallthrough' statement. (Ville)
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240926134322.3728021-5-ankit.k.nautiyal@intel.com
On MST links - at least for some MST branch devices - the list of modes
returned to users on an enabled link depends on the current link
rate/lane count parameters (besides the DPRX link capabilities, any MST
branch BW limit and the maximum link parameters reduced after LT
failures). In particular the MST branch BW limit may depend on the link
rate/lane count parameters programmed to DPCD. After an LT failure and
limiting the maximum link parameters accordingly, users should see a
mode list reflecting these new limits. However with the current fallback
order this isn't ensured, as the new limit could allow for modes
requiring a higher link BW, but these modes will be filtered out due to
the enabled link's lower link BW.
Ensure that the mode list changes in a consistent way after a link
training failure and reducing the link parameters by changing the
fallback order on MST links to happen in BW order.
v2:
- s/INTEL_DP_MAX_SUPPORTED_LANE_COUNTS/INTEL_DP_MAX_SUPPORTED_LANE_CONFIGS
and s/num_common_lane_counts/num_common_lane_configs to make the
difference wrt. max lane counts clearer. (Suraj)
- Add a TODO comment to make the SST fallback logic work the same way as
MST. (Arun)
- Use sort_r()'s default swap function instead of a custom one.
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240729144458.2763667-1-imre.deak@intel.com
Add connector debugfs entries to force the link rate/lane count to be
used by a link training afterwards. These settings will be clamped to
the supported, i.e. the source's and sink's common rate/lane count.
After forcing the link rate/lane count reset the link training
parameters and for a non-auto setting disable reducing the link
parameters via the fallback logic. The former one can be used after
testing link training failure scenarios - via debugfs entries added
later - to reset the reduced link parameters after the test.
v2:
- Add the entries from intel_dp_link_training.c (Jani)
- Rename the entries to i915_dp_set_link_rate/lane_count.
v3: (Ville)
- Rename the entries/struct fields to force_link_rate/lane_count.
- Lock connection_mutex only for the required intel_dp state.
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-18-imre.deak@intel.com
Recheck the link state after a passing link training, with a 2 sec delay
to account for cases where the link goes bad following the link training
and the sink doesn't report this via an HPD IRQ.
The delayed work added here will be also used by a later patch after a
failed link training to try to retrain the link with unchanged link
params before reducing the link params.
v2: Don't flush an uninitialized delayed work (on HDMI-only DDI ports).
v3:
- Move the helpers to a new intel_encoder.c file, rename them
accordingly. (Ville)
- Add the work to intel_encoder instead of intel_digital_port.
- Call the encoder specific link check function via an encoder hook.
- Flush the link check work during encoder destroy from
intel_dp_encoder_flush_work().
- Flush the link check work during encoder suspend as well.
v4: Call intel_encoder_link_check_init() with a valid encoder pointer.
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610181428.2955658-1-imre.deak@intel.com
The DSC HW state of DP connectors is read out during driver loading and
system resume in intel_modeset_update_connector_atomic_state(). This
function is called for all connectors though and so the state of DSI
connectors will also get updated incorrectly, triggering a WARN there
wrt. the DSC decompression AUX device.
Fix the above by moving the DSC state readout to a new DP connector
specific sync_state() hook. This is anyway the logical place to update
the connector object's state vs. the connector's atomic state.
Fixes: b2608c6b32 ("drm/i915/dp_mst: Enable MST DSC decompression for all streams")
Reported-and-tested-by: Drew Davenport <ddavenport@chromium.org>
Closes: https://lore.kernel.org/all/Zb0q8IDVXS0HxJyj@chromium.org
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240205132631.1588577-1-imre.deak@intel.com
