From: Mario Kleiner <mario.kleiner.de@gmail.com>
To: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: mario.kleiner.de@gmail.de,
intel-gfx <intel-gfx@lists.freedesktop.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Daniel Vetter <daniel.vetter@ffwll.ch>
Subject: Re: [PATCH] drm/i915/dp: Add current maximum eDP link rate to sink_rate array.
Date: Thu, 9 Jan 2020 18:57:14 +0100 [thread overview]
Message-ID: <CAEsyxyhjbP6ADutU7XRJUjryj1+X8mFqopB9TvBoW6RWjBihww@mail.gmail.com> (raw)
In-Reply-To: <20200109164715.GD13686@intel.com>
[-- Attachment #1.1: Type: text/plain, Size: 2531 bytes --]
On Thu, Jan 9, 2020 at 5:47 PM Ville Syrjälä <ville.syrjala@linux.intel.com>
wrote:
> On Thu, Jan 09, 2020 at 05:30:05PM +0100, Mario Kleiner wrote:
> > On Thu, Jan 9, 2020 at 4:38 PM Ville Syrjälä <
> ville.syrjala@linux.intel.com>
> > wrote:
> >
> > > On Thu, Jan 09, 2020 at 05:26:57PM +0200, Ville Syrjälä wrote:
> > > > On Thu, Jan 09, 2020 at 04:07:52PM +0100, Mario Kleiner wrote:
> > > > > The panel reports 10 bpc color depth in its EDID, and the UEFI
> > > > > firmware chooses link settings at boot which support enough
> > > > > bandwidth for 10 bpc (324000 kbit/sec to be precise), but the
> > > > > DP_MAX_LINK_RATE dpcd register only reports 2.7 Gbps as possible,
> > >
> > > Does it actually or do we just ignore the fact that it reports
> 3.24Gbps?
> > >
> > > If it really reports 3.24 then we should be able to just add that to
> > > dp_rates[] in intel_dp_set_sink_rates() and be done with it.
> > >
> > > Although we'd likely want to skip 3.24 unless it really is reported
> > > as the max so as to not use that non-standard rate on other displays.
> > > So would require a bit fancier logic for that.
> > >
> > >
> > Was also my initial thought, but the DP_MAX_LINK_RATE reg reports 2.7
> Gbps
> > as maximum.
>
> So dpcd[0x1] == 0xa ?
>
>
Yes. [*]
> What about the magic second version of DP_MAX_LINK_RATE at 0x2201 ?
> Hmm. I guess we should already be reading that via
> intel_dp_extended_receiver_capabilities().
>
Yes, you do.
[*] Well, i have to recheck on the machine. I started this work on the AMD
side and checked what AMD DC gave me, haven't rechecked stuff under i915
that i already knew from AMD. Comparing the implementations, there's some
peculiar differences that may matter:
intel_dp_extended_receiver_capabilities() is more "paranoid" than AMD DC's
retrieve_link_cap() function in deciding if the extended receiver caps are
valid. Intels implementation copies only the first 6 Bytes of extended
receiver caps into the dpcd[] arrays, whereas AMD copies 16 Bytes. Not sure
about the differences, but one of you may wanna check why this is, and if
it matters somehow.
Btw. your proposed
/* blah */
if (max_rate > ...)
wouldn't work if dpcd[0x1] == 0xa, which it likely is [*]. AMD DC
identified it as DP 1.1, eDP 1.3, and these extended caps seem to be only
part of DP 1.3+ if i understand the comments in
intel_dp_extended_receiver_capabilities() correctly.
-mario
>
> --
> Ville Syrjälä
> Intel
>
[-- Attachment #1.2: Type: text/html, Size: 3631 bytes --]
[-- Attachment #2: Type: text/plain, Size: 160 bytes --]
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-01-09 17:57 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 15:07 [PATCH] drm/i915/dp: Add current maximum eDP link rate to sink_rate array Mario Kleiner
2020-01-09 15:26 ` Ville Syrjälä
2020-01-09 15:38 ` Ville Syrjälä
2020-01-09 16:30 ` Mario Kleiner
2020-01-09 16:47 ` Ville Syrjälä
2020-01-09 17:57 ` Mario Kleiner [this message]
2020-01-09 18:24 ` Ville Syrjälä
2020-01-09 20:19 ` Mario Kleiner
2020-01-10 13:32 ` Ville Syrjälä
2020-01-10 15:50 ` Mario Kleiner
2020-01-09 16:31 ` Ville Syrjälä
2020-01-09 16:27 ` Mario Kleiner
2020-01-09 15:39 ` Alex Deucher
2020-01-09 16:46 ` Mario Kleiner
2020-01-09 19:49 ` Alex Deucher
2020-01-09 21:04 ` Mario Kleiner
2020-01-09 21:26 ` Harry Wentland
2020-01-10 16:02 ` Mario Kleiner
2020-01-10 18:09 ` [Intel-gfx] " Ville Syrjälä
2020-01-15 12:34 ` Jani Nikula
2020-01-15 14:17 ` Ville Syrjälä
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAEsyxyhjbP6ADutU7XRJUjryj1+X8mFqopB9TvBoW6RWjBihww@mail.gmail.com \
--to=mario.kleiner.de@gmail.com \
--cc=daniel.vetter@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=mario.kleiner.de@gmail.de \
--cc=ville.syrjala@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).