intel_dp_hdmi_sink_max_frl() limits the sink's max FRL rate by its
DSC max FRL rate whenever the sink supports DSC 1.2.
However, the DSC max FRL rate (HF-VSDB DSC_Max_FRL_Rate) only applies
to compressed video transport, which requires a DSC 1.2 encoder in
the PCON (configured via intel_dp_pcon_dsc_configure()).
Without such an encoder the HDMI link always carries uncompressed
video, for which the regular Max_FRL_Rate is the correct limit.
Applying the DSC limit unconditionally trains the FRL link at a lower
rate than both the PCON and the sink support.
E.g. an LG OLED G4 (Max_FRL_Rate 48 Gbps, DSC_Max_FRL_Rate 24 Gbps)
behind a Synaptics VMM7100 PCON (PCON max FRL bw 48 Gbps, no DSC
encoder):
Sink max rate from EDID = 24 Gbps
FRL trained with : 24 Gbps
while Windows/macOS train the same hardware at 40/48 Gbps.
The too low FRL rate needlessly constrains the formats available to
the sink.
Only apply the sink's DSC max FRL rate if the PCON has a DSC 1.2
encoder, matching the gate in intel_dp_pcon_dsc_configure().
PCONs with a DSC encoder keep the current conservative behavior,
since the link is trained once and compressed transport may be used
for any subsequent mode.
With this the setup above trains at 48 Gbps.
Tested on PTL (xe) with the above PCON/sink combo.
Fixes: 10fec80b48 ("drm/i915/display: Configure PCON for DSC1.1 to DSC1.2 encoding")
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Alexander Kaplan <alexander.kaplan@sms-medipool.de>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20260718105207.5565-3-alexander.kaplan@sms-medipool.de
For modes which fit through the link uncompressed only with a 6 bpc
pipe BPP, the link config currently selects 6 bpc with dithering even
if the sink supports DSC.
For HDMI sinks behind a DP to HDMI protocol converter this is the
wrong preference: HDMI knows no 6 bpc transport format, so the
converter has to expand the dithered 6 bpc stream back to 8 bpc for
the HDMI link anyway, and DSC with an at least 8 bpc input provides
a better output quality than that.
Prefer DSC, following the pattern commit ba49a4643c ("drm/i915/dp:
Set min_bpp limit to 30 in HDR mode") uses for HDR: keep the
uncompressed minimum pipe BPP at 8 bpc if the sink supports DSC,
making the uncompressed link config fail for such modes and the mode
fall back to DSC.
As there, if the DSC computation fails, the mode falls back to YCbCr
4:2:0 where supported, or gets rejected.
Besides the output quality, some converters can't even display a
6 bpc stream at high pixel clocks.
Synaptics VMM PCON based DP to HDMI 2.1 adapters from two device
families (branch device IDs SYNAq and SYNAa) output corrupted FRL
timings for an uncompressed RGB 6 bpc 4k120 (1188 MHz) stream,
resulting in a black screen, while the same mode works with DSC
(12 bpc input) and 6 bpc works at lower pixel clocks.
Windows and macOS drive 4k120 on these devices only via DSC.
A lower bpc limit explicitly requested via the max bpc connector
property is still honored.
This keeps the current uAPI behavior (exercised by IGT kms_dither)
and provides an escape hatch for sinks with a broken DSC
implementation.
DP and eDP sinks, and HDMI sinks without DSC support, are not
affected and keep falling back to 6 bpc.
Tested on PTL (xe) with the above PCONs and an LG OLED G4.
Cc: Imre Deak <imre.deak@intel.com>
Cc: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Alexander Kaplan <alexander.kaplan@sms-medipool.de>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20260718105207.5565-2-alexander.kaplan@sms-medipool.de
Per DP 1.4a section 2.2.4.3, the MSA MISC1 VSC_SDP bit signals that
the sink should defer colorimetry to the VSC SDP. It should only be set
when the sink advertises DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED and a
VSC SDP with pixel encoding/colorimetry payload will actually be sent.
Fold the colorimetry_support check into intel_dp_needs_vsc_colorimetry()
so both intel_ddi_set_dp_msa() and intel_dp_compute_vsc_sdp() share a
single consistent gate.
Assisted-by: GitHub_Copilot:claude-sonnet-4.6
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Pranay Samala <pranay.samala@intel.com>
Link: https://patch.msgid.link/20260709113951.3557968-3-chaitanya.kumar.borah@intel.com
From PTL onwards, the set context latency can be in the vactive region,
letting the safe window start some lines before the vblank start. The DSB
waits on this safe window instead of vblank (bits [15:14] select the safe
window signal from the DPT unit to start the DMA engine).
With modes that have a smaller vblank region, the computed guardband is
clamped to the vblank length, making the undelayed and delayed vblank
coincide. If the SCL is also 0, the 'safe window' becomes effectively 0,
and the DSB configured to wait for it gets stalled, since the hardware
never signals the safe window, leading to:
*ERROR* [CRTC:159:pipe A] flip_done timed out
*ERROR* [CRTC:159:pipe A] DSB 0 timed out waiting for idle
Keep the set context latency at a minimum of 1 to avoid this.
v2: Fix the bit numbers and correct the commit message. (Chaitanya)
Fixes: 4a68c7516c ("drm/i915/dsb: Use safe window path when VRR TG is used")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Assisted-by: GitHub-Copilot:Claude-Opus-4.8
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Link: https://patch.msgid.link/20260722062449.1166411-1-ankit.k.nautiyal@intel.com
Wa_16030862157:
Interpret 0xF populated-channel count as 16
The register MEM_SS_INFO_GLOBAL [Number of populated channels] field
definition is updated with an encoding for 16 channels.
For 16-channel configuration, program 1111b. A programmed value of 1111b
must be interpreted as 16 channels for memory bandwidth calculations.
The MEM_SS_INFO_GLOBAL populated-channel field is only 4 bits and cannot
encode 16, so on Xe3p the BIOS programs the saturated field value (0xf)
to indicate the fully-populated 16-channel config (4 memory controllers
x 4 channels). Interpret it as 16 and let the bandwidth math handle the
larger channel count.
v2: Limit the WA only till NVL (Suraj)
Logical separation of WA (Vinod)
WA: 16030862157, 16030875223
Bspec: 69131, 79482
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Link: https://patch.msgid.link/20260715143243.4141208-2-uma.shankar@intel.com
Disable 1 and 2 lane link configurations on UHBR tunneled links,
according to DP Standard v2.1b "3.5.2.16.3 128b/132b DPRX Lane Count
Conversion Failure Indication and Corrective Action". A tunnel can
indicate if it's not affected by this limitation, check for that and
skip disabling the unsupported lanes for a well-behaving tunnel.
The Standard in the same section also describes a workaround for 2 lanes
which requires assisstance from the sink, where the sink indicates at
the end of the link training sequence if the link training must be
retried. This mechanism also requires quirking out some sinks - based on
the sink's DPCD OUI and EDID identifications - which doesn't implement
this link training feedback indication properly. This patch leaves the
implementation of this workaround for a follow-up, but prepares for it
already by detecting the supported number of lane counts at a place
where both DPCD OUI and EDID is available for the quirk detection.
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260714152700.555527-6-imre.deak@intel.com
Enable link training fallback between UHBR and non-UHBR link rates on DP
SST links. This was disabled so far to preserve the fallback behavior.
There isn't a known issue related to such a fallback and DP MST has been
using this for a while already. Also, enabling UHBR rates over
Thunderbolt tunnels in a follow-up change, which at least on some links
supports only 4 lanes and not 1 or 2 lanes on UHBR, makes a
UHBR->non-UHBR fallback scenario more likely.
At the same time align the corresponding link training fallback kunit
test, allowing a UHBR <-> non-UHBR fallback there as well.
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.comd>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260714152700.555527-4-imre.deak@intel.com
Turns out some panels allow only AUX based backlight
by just setting the DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP and
not setting the DP_EDP_BACKLIGHT_AUX_ENABLE_CAP.
If we make DP_EDP_BACKLIGHT_AUX_ENABLE_CAP a necessity for AUX
based DPCD backlight these panels loose the ability to manipulate
backlight via AUX, especially ones with no PWM controller.
Remove this check from function so that panels who do not advertise
DP_EDP_BACKLIGHT_AUX_ENABLE_CAP but advertise
DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP are able to manipulate
backlight again.
Fixes: ed8be780bd ("drm/i915/backlight: Fix VESA backlight possible check condition")
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16507
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Link: https://patch.msgid.link/20260716030959.436430-1-suraj.kandpal@intel.com
Double the fractional part of the horizontal scale factor
for the purposes of min_cdck calculation. This bumps the min
CDCLK sufficiently to overcome some kind of 2 PPC granularity
issue. Without this CDCLK may end up being too low and we get
underruns with certain horizontal downscale factors.
The current Bspec formula calls for doubling only the
fractional part below 0.5, and rounding it down to a
unit fraction. But that formula does not result in a
sufficient CDCLK bump in a lot of cases. Empirical evidence
supports doubling the entire fractional part, so let's just
do that while we wait for further analysis from the hardware
team.
Also note that the position of the scaler output window also
seems to matter. If the output is near the left edge of the
screen then lower CDCLK is sufficient, but moving the output
window further to the right causes underruns unless CDCLK is
also bumped. Some prefill happening during hblank already?
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260715120926.10786-5-ville.syrjala@linux.intel.com
Reviewed-by: Nemesa Garg <nemesa.garg@intel.com>
Tested-by: Vidya Srinivas <vidya.srinivas@intel.com>
Since commit 860e748bdd ("drm: ensure blend mode supported if pixel
format with alpha exposed"), drm_mode_config_validate() warns when a
plane exposes an alpha pixel format but not the "pixel blend mode"
property. The cursor (ARGB8888, all platforms) and the VLV/CHV primary
and sprite planes trip this.
Userspace has historically assumed premultiplied blending when the
property is not attached, so it is safe to assume that planes that
did not expose the property already blended with fixed pre-multiplied
alpha in hardware. Therefore, expose a "pixel blend mode" property
advertising only DRM_MODE_BLEND_PREMULTI to match that assumption and
silence the warning. The cursor call is unconditional; the primary and
sprite calls are gated to VLV/CHV, the only platforms whose format lists
include alpha formats.
Assisted-by: Claude:claude-opus-4-8
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16623
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20260715054221.451421-1-chaitanya.kumar.borah@intel.com
On Xe3+, the SoC can lower the fabric frequency when the display
needs less bandwidth than the minimum GV point. This threshold is
defined as 20 GB/s. The driver can choose to request this threshold
when the required data rate falls below it.
Add an extra QGV entry, with both peak bw and derated bw set to
20 GB/s, to the bandwidth info when all of the following hold:
1. The platform is Xe3+.
2. There is at least one existing QGV point.
3. The number of QGV points is below 8 (the maximum).
Once a plane group is found, the driver iterates over all QGV points
in that group to find the best match for the required data rate. If
the required data rate is below 20 GB/s, it selects the peak bw from
this new QGV point (20 GB/s).
v2: add the peak bandwidth threshold as an additional QGV entry
v3: drm_warn switched to drm_dbg_kms (Suraj)
Removed log in case of no sagv and some tweak in the log message
if the system has already the maximum number of QGV points
Bspec: 68880
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260615203355.218578-8-vinod.govindapillai@intel.com
Simplify the initialization of QGV points info by extracting
the code to initialize the QGV points info from dram info based
on the memory type. This will reduce the complexity of the init
QGV info routine as we will be supporting new memory types in
future platforms.
v2: rebase after Ville's refactoring
v3: patch description updated
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260615203355.218578-5-vinod.govindapillai@intel.com
Remove the fallback for VRAM to system memory, I tested it and that
doesn't work at all, only a black screen with pipe fault errors were
observed.
On systems with media GT, extra latency is added when accessing stolen
memory when the GT is in MC6. Since we additionally aren't counting how
much memory is used for stolen and we could in theory fill up the
entire stolen area with DPT's, avoid using stolen and only use the
default memory region.
Using stolen may also result in random system hangs under load.
Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/work_items/7513
Fixes: 775d0adc01 ("drm/xe/fbdev: Limit the usage of stolen for LNL+")
Cc: <stable@vger.kernel.org> # v6.12+
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patch.msgid.link/20260630135523.1775379-2-dev@lankhorst.se
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
Acked-by: Matthew Brost <matthew.brost@intel.com> #teams
Inform the poor sop reading the logs why the initial FB was rejected
if there is no stolen memory.
Technically this should perhaps be an error since the plane is known
to be enabled at this point, and if there is no stolen then it clearly
can't be scanning out from anywhere. But maybe there are some
virtualization passthrough cases and whatnot where we might not be
able to get access to stolen, so keep it as debug (same as i915).
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patch.msgid.link/20260511214122.8468-9-ville.syrjala@linux.intel.com
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
Acked-by: Matthew Brost <matthew.brost@intel.com> #teams
Properly turn off the plane if it is enabled but
.get_initial_plane_config() failed for whatever reason.
The hardware does (or at least did) perform some kind of automagic
plane disable when the pipe gets disabled, but we don't rely on that
anywhere else either. Also the GGTT/actual memory may get clobbered
afterwards, so leaving the plane enabled here could result in visual
corruption/GTT faults/etc.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patch.msgid.link/20260511214122.8468-2-ville.syrjala@linux.intel.com
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
Commit 16df4cc63c ("drm/i915/display: Use ceiling division for NV12
UV surface offset calculation") computes the UV (chroma) surface
start/size as ceiling(half of Y plane start/size) directly from the
U16.16 fixed-point source rectangle:
x = fp_16_16_to_int_ceil(fp_16_16_div2(src.x1));
For a single pipe the source coordinates are integers, so this is
correct.
(UV start = ceiling(half of Y plane start)).
With bigjoiner + a plane scaler the picture changes. The pipe boundary
is a fixed integer destination pixel, but the plane's position and the
scaler ratio are arbitrary, so drm_rect_clip_scaled() maps the seam back
to a *fractional* per-pipe source. For a 1280->2407 upscaled NV12 plane
crossing the seam:
master src: width = 1204 * 1280/2407 = 640.265899, x1 = 0
joiner src: width = 1203 * 1280/2407 = 639.734115, x1 = 640.265884
The luma path floors this to an integer (src.x1 >> 16 = 640), but the
UV path takes ceiling(640.265884 / 2) = ceil(320.13) = 321. The Y plane
then starts at column 640 while the UV plane starts at 321*2 = 642,
pushing the chroma read one column past the 640-wide chroma surface on
the joiner secondary:
[CRTC:382:pipe C] PLANE ATS fault
[CRTC:382:pipe C][PLANE:267:plane 1C] fault (CTL=0x81009400, ...)
The spec "Y plane start" is the integer pixel the luma surface actually
programs (640), not the pre-floor fixed-point value (640.27). Convert
the Y plane start/size to integer first - matching skl_check_main_surface()
- and then apply the ceiling. This is a no-op for the integer (non-joiner)
case and yields the correct, in-bounds chroma offset for the fractional
joiner seam:
before fix after fix
master 1B: x=0 w=321 x=0 w=320 -> [0, 320)
slave 1C: x=321 w=320 x=320 w=320 -> [320, 640)
The two halves now tile the 640-wide chroma plane exactly and the ATS
fault is gone.
Assisted-by: GitHub-Copilot:Claude-Opus-4.8
Fixes: 16df4cc63c ("drm/i915/display: Use ceiling division for NV12 UV surface offset calculation")
Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
Reviewed-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patch.msgid.link/20260618181837.687302-1-vidya.srinivas@intel.com
Add KUnit tests for DP link fallback selection across eDP, SST, and MST.
Verify that the fallback logic properly selects the maximum allowed
configuration, iterates through allowed configurations, and disables
failed configs as expected.
These tests include UHBR vs. non-UHBR conditions, MST vs. SST mode,
and validate that subsequent fallback selections respect the updated
allowed configuration mask.
v2:
- Rebase on changes using a filter object instead of a mask of
configuration indices.
- Rebase on changes using an iteration object.
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260701153204.4124150-35-imre.deak@intel.com
Add KUnit tests for link_caps updates shrinking or expanding the
supported rates and lane counts.
The tests also cover updates with disabled configurations, including
random shrink and expand sequences, to verify that disabled state,
allowed configurations, ordering, and max limits stay consistent across
updates.
v2: Remove test cases for the now unused merge update mode.
v3:
- Test config iteration in lane count, rate order as well.
- Keep space after comma in code comment. (Michał)
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com> # v2
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260707124849.135319-4-imre.deak@intel.com
Add a simple baseline test for DP link caps iteration using a fixed
standard DP configuration table. This provides a minimal validity check,
independent of more complex test setups, verifying the iterator returns
expected configurations in ascending and descending order.
v2: Unchanged.
v3: Test config iteration in lane count, rate order as well.
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com> # v2
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260707124849.135319-3-imre.deak@intel.com
