Ville, It appears we are receiving some minimal information about the DP to dual-link DVI adapter which may be used to indicate dual-link support. Any chance we can use this information to augment the EDID to not filter out the higher clocks? > 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. [CONNECTOR:95:DP-1]: status: connected ... DP branch device present: yes Type: DVI ID: ***m2DVIa*** HW: 0.1 SW: 2.0 ... I very well may be barking up the wrong tree with the following: The "DP-1" reports a "branch device" with an "ID" of m2DVIa which is mentioned in another (amd) video driver: > +/*DP to Dual link DVI converter*/ > +static const uint8_t DP_DVI_CONVERTER_ID_4[] = "m2DVIa"; > +static const uint8_t DP_DVI_CONVERTER_ID_5[] = "3393N2"; from https://lore.kernel.org/patchwork/patch/1338037/ This is used here which appears to do something with I2C: https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c#L309 There are mention of a small number of "external converter chips" which are used in the above conditional: https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/amd/display/include/ddc_service_types.h#L30 Thanks, Adam On Fri, Jun 4, 2021, at 1:13 PM, Ville Syrjälä wrote: > 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 >
