From: Rajat Jain <rajatja@google.com>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: "Sean Paul" <seanpaul@google.com>,
"David Airlie" <airlied@linux.ie>,
"Sugumaran Lacshiminarayanan" <slacshiminar@lenovo.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Daniel Thompson" <daniel.thompson@linaro.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Mark Pearson" <mpearson@lenovo.com>,
"Tomoki Maruichi" <maruichit@lenovo.com>,
"Jesse Barnes" <jsbarnes@google.com>,
"Rajat Jain" <rajatxjain@gmail.com>,
intel-gfx@lists.freedesktop.org, "Mat King" <mathewk@google.com>,
"José Roberto de Souza" <jose.souza@intel.com>,
"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
"Sean Paul" <sean@poorly.run>,
"Duncan Laurie" <dlaurie@google.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Pavel Machek" <pavel@denx.de>,
"Nitin Joshi1" <njoshi1@lenovo.com>
Subject: Re: [PATCH v6 2/3] drm/i915: Lookup and attach ACPI device node for connectors
Date: Mon, 9 Mar 2020 17:09:23 -0700 [thread overview]
Message-ID: <CACK8Z6FW3p6h1pfW2kPxiwBoDDcK3R76Aoxa-17P+MpU+w20hw@mail.gmail.com> (raw)
In-Reply-To: <CACK8Z6HFOpsfhHo=y9Qj_NSdiCGBHsvchZ335mU1BQ5CYQq1VQ@mail.gmail.com>
On Fri, Mar 6, 2020 at 5:38 PM Rajat Jain <rajatja@google.com> wrote:
>
> On Fri, Mar 6, 2020 at 1:42 AM Jani Nikula <jani.nikula@linux.intel.com> wrote:
> >
> > On Thu, 05 Mar 2020, Rajat Jain <rajatja@google.com> wrote:
> > > On Thu, Mar 5, 2020 at 1:41 AM Jani Nikula <jani.nikula@linux.intel.com> wrote:
> > >>
> > >> On Wed, 04 Mar 2020, Rajat Jain <rajatja@google.com> wrote:
> > >> 1) See if we can postpone creating and attaching properties to connector
> > >> ->late_register hook. (I didn't have the time to look into it yet, at
> > >> all.)
> > >
> > > Apparently not. The drm core doesn't like to add properties in
> > > late_register() callback. I just tried it and get this warning:
> >
> > I kind of had a feeling this would be the case, thanks for checking.
>
> Thinking about it again, it looks like there is a difference in
> creating a property and attaching a property. I'm wondering if drm
> would let me (unconditionally) create a property before registering,
> and attach it in late_register() only in case a privacy screen is
> detected. (If not present, I can destroy the property in
> late_register()). If this approach sound more promising, I can try it
> out.
I tried out this approach, and it worked. The new patchset is posted at:
https://patchwork.freedesktop.org/series/74473/#rev1
Thanks!
Rajat
>
> >
> > >> 2) Provide a way to populate connector->acpi_device_id and
> > >> connector->acpi_handle on a per-connector basis. At least the device id
> > >> remains constant for the lifetime of the drm_device
> > >
> > > Are you confirming that the connector->acpi_device_id remains constant
> > > for the lifetime of the drm_device, as calculated in
> > > intel_acpi_device_id_update()? Even in the face of external displays
> > > (monitors) being connected and disconnected during the lifetime of the
> > > system? If so, then I think we can have a solution.
> >
> > First I thought so. Alas it does not hold for DP MST, where you can have
> > connectors added and removed dynamically. I think we could ensure they
> > stay the same for all other connectors though. I'm pretty sure this is
> > already the case; they get added/removed after all others.
> >
> > Another thought, from the ACPI perspective, I'm not sure the dynamically
> > added/removed DP MST connectors should even have acpi handles. But
> > again, tying all this together with ACPI stuff is not something I am an
> > expert on.
>
> I propose that we:
>
> 1) Maintain a display_index[] array within the drm_dev, and increment
> as connectors are added.
> 2) Initialize connector->acpi_device_id and and connector->acpi_handle
> while registering (one time per connector).
> 3) Remove the code to update acpi_device_id on every resume.
>
> It doesn't look like anyone on the DP MST side has cared for ACPI so
> far, so I doubt if we can do anything that might break MST currently.
> In other words, the above should not make things any worse for MST, if
> not better. For connectors other than MST, this should allow them to
> get ACPI handle and play with it, if they need.
>
> WDYT?
>
> Thanks,
>
> Rajat
>
> >
> > >> (why do we keep
> > >> updating it at every resume?!) but can we be sure ->acpi_handle does
> > >> too? (I don't really know my way around ACPI.)
> > >
> > > I don't understand why this was being updated on every resume in that
> > > case (this existed even before my patchset). I believe we do not need
> > > it. Yes, the ->acpi_handle will not change if the ->acpi_device_id
> > > does not change. I believe the way forward should then be to populate
> > > connector->acpi_device_id and connector->acpi_handle ONE TIME at the
> > > time of connector init (and not update it on every resume). Does this
> > > sound ok?
> >
> > If a DP MST connector gets removed, should the other ACPI display
> > indexes after that shift, or remain the same? I really don't know.
> >
> > BR,
> > Jani.
> >
> > --
> > Jani Nikula, Intel Open Source Graphics Center
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next prev parent reply other threads:[~2020-03-10 8:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200305012338.219746-1-rajatja@google.com>
2020-03-05 1:23 ` [PATCH v6 1/3] intel_acpi: Rename drm_dev local variable to dev Rajat Jain
2020-03-05 9:14 ` Jani Nikula
2020-03-05 1:23 ` [PATCH v6 2/3] drm/i915: Lookup and attach ACPI device node for connectors Rajat Jain
2020-03-05 9:40 ` Jani Nikula
2020-03-06 3:27 ` Rajat Jain
2020-03-06 9:42 ` Jani Nikula
2020-03-07 1:38 ` Rajat Jain
2020-03-10 0:09 ` Rajat Jain [this message]
2020-03-05 1:23 ` [PATCH v6 3/3] drm/i915: Add support for integrated privacy screens Rajat Jain
2020-03-05 10:01 ` Jani Nikula
2020-03-06 3:35 ` Rajat Jain
2020-03-06 10:15 ` Jani Nikula
2020-03-07 1:27 ` Rajat Jain
2020-03-05 1:19 [PATCH v6 1/3] intel_acpi: Rename drm_dev local variable to dev Rajat Jain
2020-03-05 1:19 ` [PATCH v6 2/3] drm/i915: Lookup and attach ACPI device node for connectors Rajat Jain
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