On Fri, Jun 04, 2021 at 12:57:25PM -0400, Adam Chasen wrote: > Thanks for staying with me! Still hoping I can get back to using KMS/Wayland combination with my setup. > > I understand the current recommendation is to push the mode setting to the wayland compositor per Ville here: https://gitlab.freedesktop.org/drm/intel/-/issues/393#note_337616 > > Alas, I am using Mutter (similar to issue #393) which (historically) doesn't support mode setting (yet?). > > There is mention of drm_dp_downstream_max_clock() in an i915 comment, which looks like could be a reference to drm_dp_downstream_max_tmds_clock(). > > It seems there is a hard coded 165MHz max for DP_DWN_STRM_PORT_TYPE_TMDS or (note the comment in the below code): > > case DP_DS_PORT_TYPE_DVI: > if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DETAILED_CAP_INFO_AVAILABLE) == 0) > return 165000; > /* FIXME what to do about DVI dual link? */ > return port_cap[1] * 2500; > > Still wondering about the "one byte" format is for configuration, but I presume it is setting DP_DETAILED_CAP_INFO_AVAILABLE to 0 which triggers this. > > Is there a recommended approach to setting the port to support Dual-Link based on EDID response (or is it too late by the time we get the EDID)? EDID can't help us since it would only tell us whether the display supports dual-link or not. The dongle may still be single link only. > > Is there a recommended approach for a "disable filter", or "manual modeset"? There are others who seem interested in overriding the filtering logic (e.g. "do what I say even though it isn't clear it will work"). https://gitlab.freedesktop.org/drm/intel/-/issues/393#note_829142 Userspace is free to force any it wants. But I guess mutter+wayland doesn't support that for some reason. I've occasionally pondered about adding some kind of connector property for this, but not sure wht it should look like. And it would still require userspace support to set it. Another idea would be to extend the video= cmdline with some kind of knob that lets you override these limits. But again it's a bit hard to come up with a decent solution since there are various different clock limits involved (TMDS clock for HDMI vs. link rate for DP, dotclock for everyting). And just saying "ignore all limits" is not a very flexible solution since there may be some limit you do want to enforce, just not as low as what we would auto-detect. > > -Adam > > -- Related -- > > I found these following a thread on the 165MHz clock limit in the context of DP dual mode HDMI dongles with a patch experimenting with turning off the limit: https://bugs.freedesktop.org/show_bug.cgi?id=112018#c2 (now https://gitlab.freedesktop.org/drm/intel/-/issues/511) There is even a hack for what appears to be a similar limitation > (using Dual mode DP): https://github.com/hansmi/fake-dp-dual-mode > > Researching answers for previous questions: > > "one byte" cap: > /* > * 0x80-0x8f describe downstream port capabilities, but there are two layouts > * based on whether DP_DETAILED_CAP_INFO_AVAILABLE was set. If it was not, > * each port's descriptor is one byte wide. If it was set, each port's is > * four bytes wide, starting with the one byte from the base info. As of > * DP interop v1.1a only VGA defines additional detail. > */ > > And from a commit: > * Fixup logic for calculating the downstream port length to account for > the fact that downstream port caps can be either 1 byte or 4 bytes > long. We can actually skip fixing the max_clock/max_bpc helpers here > since they all check for DP_DETAILED_CAP_INFO_AVAILABLE anyway. > > DPCD = DisplayPort Configuration Data > DFP appears to be a structure to hold configuration data as part of intel_attached_dp(connector): > /* Downstream facing port caps */ > struct { > int min_tmds_clock, max_tmds_clock; > int max_dotclock; > u8 max_bpc; > bool ycbcr_444_to_420; > } dfp; > > On Mon, May 31, 2021, at 10:28 AM, Adam Chasen wrote: > > Ville, > > Thanks for the additional detail! > > > > I looked up HPD and understand it is hot plug detection, but I didn't > > find much for "one byte caps format". I assume this is short hand for > > "capability format". > > > > Is the "one byte" format a limitation from the monitor, the dongle, the > > motherboard, or the chipset? > > > > What are some examples of other "capability formats"? > > > > Is there a recommended approach to setting the port to support > > Dual-Link based on EDID response (or is it too late by the time we get > > the EDID)? > > > > If there is no obvious automatic solution, do you have an example of a > > "manual override" (i.e. module argument) for another situation I can > > use as a guide? > > > > Still curious what DPCD DFP stands for. > > > > Thanks, > > Adam > > > > On Mon, May 31, 2021, at 10:15 AM, Ville Syrjälä wrote: > > > On Fri, May 28, 2021 at 02:15:46PM -0400, Adam Chasen wrote: > > > > Any further advice on tracing what is triggering what appears to be the limitation of the clock? My guess is it is imposing a DVI Single-Link speed (165000) limitation on the dual-link DVI adapter. > > > > > > > > > TMDS clock 25000-165000 > > > > > > > > I am able to override in xorg with xrandr to 268500 > > > > > > > > Per Ville's request: > > > > DPCD DFP: 0a > > > > > > > > What is the DPCD DFP? > > > > > > It indicates the port is DVI with HPD capability. But unfortunately it's > > > using the one byte caps format which doesn't let us differentiate > > > between single link and dual link DVI. So we take the more cautious > > > apporach and assume it's single link. > > > > > > > > > > > Thanks, > > > > Adam > > > > > > > > On Wed, May 12, 2021, at 5:07 PM, Adam Chasen wrote: > > > > > Ville, > > > > > DPCD DFP: 0a > > > > > > > > > > What is the DPCD DFP? > > > > > > > > > > Additional info, this is the first time there has been an issue with > > > > > this adapter not working (i.e. it must have been operating above > > > > > 165MHz), but it is possible other drivers have "ignored" things and > > > > > just followed the EDID. > > > > > > > > > > Thanks! > > > > > Adam > > > > > > > > > > kernel: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] > > > > > [CONNECTOR:95:DP-1] > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_detect [i915]] > > > > > [CONNECTOR:95:DP-1] > > > > > kernel: [drm:drm_dp_read_dpcd_caps [drm_kms_helper]] AUX C/DDI C/PHY C: > > > > > DPCD: 11 0a 84 01 00 05 00 81 00 00 00 00 00 00 00 > > > > > kernel: [drm:drm_dp_read_desc [drm_kms_helper]] AUX C/DDI C/PHY C: DP > > > > > branch: OUI 00-80-e1 dev-ID m2DVIa HW-rev 0.1 SW-rev 2.0 quirks 0x0000 > > > > > kernel: [drm:drm_dp_read_downstream_info [drm_kms_helper]] AUX C/DDI > > > > > C/PHY C: DPCD DFP: 0a > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_detect [i915]] [ENCODER:94:DDI > > > > > C/PHY C] MST support: port: yes, sink: no, modparam: yes > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_print_rates [i915]] source > > > > > rates: 162000, 216000, 270000, 324000, 432000, 540000 > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_print_rates [i915]] sink > > > > > rates: 162000, 270000 > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_print_rates [i915]] common > > > > > rates: 162000, 270000 > > > > > kernel: [drm:drm_dp_i2c_do_msg [drm_kms_helper]] AUX C/DDI C/PHY C: > > > > > native defer > > > > > kernel: [drm:drm_dp_i2c_do_msg [drm_kms_helper]] AUX C/DDI C/PHY C: > > > > > native defer > > > > > kernel: [drm:drm_dp_i2c_do_msg [drm_kms_helper]] AUX C/DDI C/PHY C: > > > > > native defer > > > > > kernel: [drm:drm_dp_i2c_do_msg [drm_kms_helper]] AUX C/DDI C/PHY C: > > > > > native defer > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_set_edid [i915]] > > > > > [CONNECTOR:95:DP-1] DFP max bpc 8, max dotclock 0, TMDS clock > > > > > 25000-165000 > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_set_edid [i915]] > > > > > [CONNECTOR:95:DP-1] YCbCr 4:2:0 allowed? no, YCbCr 4:4:4->4:2:0 > > > > > conversion? no > > > > > kernel: [drm:drm_dp_get_edid_quirks [drm_kms_helper]] DP sink: EDID mfg > > > > > 22-f0 prod-ID 90-26 quirks: 0x0000 > > > > > kernel: [drm:drm_add_edid_modes [drm]] ELD: no CEA Extension found > > > > > kernel: [drm:drm_add_display_info [drm]] Supported Monitor Refresh rate > > > > > range is 0 Hz - 0 Hz > > > > > kernel: [drm:drm_add_display_info [drm]] non_desktop set to 0 > > > > > kernel: [drm:drm_mode_debug_printmodeline [drm]] Modeline "2560x1600": > > > > > 60 268000 2560 2608 2640 2720 1600 1603 1609 1646 0x48 0x9 > > > > > kernel: [drm:drm_mode_prune_invalid [drm]] Not using 2560x1600 mode: > > > > > CLOCK_HIGH > > > > > kernel: [drm:drm_helper_probe_single_connector_modes [drm_kms_helper]] > > > > > [CONNECTOR:95:DP-1] probed modes : > > > > > kernel: [drm:drm_mode_debug_printmodeline [drm]] Modeline "1280x800": > > > > > 60 71000 1280 1328 1360 1440 800 803 809 823 0x40 0x9 > > > > > > > > > > # for aux in /dev/drm_dp_aux* ; do dd if=$aux bs=1 count=16 > > > > > skip=$((0x80)) 2>/dev/null | hexdump -C ; done > > > > > 00000000 0a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > 00000010 > > > > > 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > 00000010 > > > > > > > > > > # for aux in /dev/drm_dp_aux* ; do dd if=$aux bs=1 2>/dev/null | > > > > > hexdump -C ; done > > > > > 00000000 11 0a 84 01 00 05 00 81 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000080 0a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > 00000090 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000100 0a 84 00 08 08 08 08 00 01 00 00 00 00 00 00 00 > > > > > |................| > > > > > 00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000200 01 00 77 77 81 00 44 44 00 00 00 00 00 00 00 00 > > > > > |..ww..DD........| > > > > > 00000210 00 80 00 80 00 80 00 80 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > 00000220 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000240 00 00 00 00 00 00 20 00 00 00 00 00 00 00 00 00 |...... > > > > > .........| > > > > > 00000250 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000300 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 80 > > > > > |................| > > > > > 00000310 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000400 47 53 53 00 00 01 01 00 01 00 00 90 02 00 00 90 > > > > > |GSS.............| > > > > > 00000410 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000500 00 80 e1 6d 32 44 56 49 61 01 02 00 00 cf 00 00 > > > > > |...m2DVIa.......| > > > > > 00000510 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > 00000600 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > 00000610 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > > > |................| > > > > > * > > > > > > > > > > On Wed, May 12, 2021, at 4:04 PM, Ville Syrjälä wrote: > > > > > > On Wed, May 12, 2021 at 12:31:14PM -0400, Adam Chasen wrote: > > > > > > > Hoping I can (help) craft a patch to address what appears to be an issue with overaggressive mode pruning. I am having trouble with rejection of a Dual-DVI compatible mode out of the DisplayPort specific to i915 in Fedora 33. It seems that drm_mode_validate_pipeline is the wall I hit when digging for why this mode is pruned. Requesting additional troubleshooting guidance. > > > > > > > > > > > > > > ``` > > > > > > > kernel: [drm:drm_mode_debug_printmodeline [drm]] Modeline "2560x1600": 60 268000 2560 2608 2640 2720 1600 1603 1609 1646 0x48 0x9 > > > > > > > kernel: [drm:drm_mode_prune_invalid [drm]] Not using 2560x1600 mode: CLOCK_HIGH > > > > > > > ``` > > > > > > > > > > > > > > This is an HP LP3065 Dual-DVI monitor connected via DisplayPort with a BizLink "active" adapter (recommended by HP and DELL for their Dual-DVI monitors). > > > > > > > > > > > > > > The adapter appears to be "transparent" to the system (unlike some adapters reporting similar issues). I2C probes and EDIDs all appear to be direct from the monitor. Though, there is a mention of a m2DVIa "branch device" in the `i915_display_info` output. > > > > > > > > > > > > > > The pruned mode works with X-Org with manually setting the mode via `xrandr` on Xorg (my current fallback setup): > > > > > > > `xrandr --newmode "2560x1600R" 268.50 2560 2608 2640 2720 1600 1603 1609 1646 +hsync -vsync` > > > > > > > > > > > > > > My setup is a bit different than some older reported "dual mode" issues (i.e. passive adapters), so I do not believe it is the "faulty dual mode detection" (i.e. https://github.com/hansmi/fake-dp-dual-mode). I was thinking it could be related by some "state" of the port detection limiting output to 165MHz clock. > > > > > > > > > > > > > > Thanks, > > > > > > > Adam > > > > > > > > > > > > > > with `echo 0x6 > /sys/module/drm/parameters/debug` > > > > > > > > > > > > > > ``` > > > > > > > kernel: [drm:drm_add_display_info [drm]] Supported Monitor Refresh rate range is 0 Hz - 0 Hz > > > > > > > kernel: [drm:drm_add_display_info [drm]] non_desktop set to 0 > > > > > > > kernel: i915 0000:00:02.0: [drm:intel_dp_set_edid [i915]] [CONNECTOR:95:DP-1] DFP max bpc 8, max dotclock 0, TMDS clock 25000-165000 > > > > > > > > > > > > That one seems to be saying that it's the adapter itself that's > > > > > > telling us it can't handle >165MHz. What does the "DPCD DFP: ..." line say? > > > > > > > > > > > > Alternatively you can do something like > > > > > > for aux in /dev/drm_dp_aux* ; do dd if=$aux bs=1 count=16 > > > > > > skip=$((0x80)) 2>/dev/null | hexdump -C ; done > > > > > > to get the raw dump.. > > > > > > > > > > > > -- > > > > > > Ville Syrjälä > > > > > > Intel > > > > > > > > > > > _______________________________________________ > > > > > Intel-gfx mailing list > > > > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx > > > > > > > > > > > -- > > > Ville Syrjälä > > > Intel > > > > > _______________________________________________ > > Intel-gfx mailing list > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx > > -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
