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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Tue, 31 Oct 2023 16:19:18 +0100
Message-ID: <CAJZ5v0ioy7n3ts9L6FQZcjngEU8qazXCdNKVXShpNL7+7hRtJg@mail.gmail.com>
Subject: Re: [PATCH v2 5/6] ACPI: scan: Extract MIPI DiSco for Imaging data
 into swnodes
To:     Sakari Ailus <sakari.ailus@linux.intel.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Linux ACPI <linux-acpi@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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Hi Sakari,

On Tue, Oct 31, 2023 at 3:00 PM Sakari Ailus
<sakari.ailus@linux.intel.com> wrote:
>
> Hi Rafael,
>
> On Tue, Oct 31, 2023 at 02:46:51PM +0100, Rafael J. Wysocki wrote:
> > Hi Sakari,
> >
> > On Tue, Oct 31, 2023 at 11:33 AM Sakari Ailus
> > <sakari.ailus@linux.intel.com> wrote:
> > >
> > > Hi Rafael,
> > >
> > > On subject:
> > >
> > > s/DiSco/DisCo/
> >
> > Huh
> >
> > Thanks for catching this!
> >
> > > On Fri, Oct 20, 2023 at 04:39:27PM +0200, Rafael J. Wysocki wrote:
> > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > >
> > > > Add information extracted from the MIPI DiSco for Imaging device
> > >
> > > Ditto.
> > >
> > > > properties to software nodes created during the CSI-2 connection graph
> > > > discovery.
> > > >
> > > > Link: https://www.mipi.org/specifications/mipi-di
> > >
> > > This URL is broken. The correct URL is:
> > >
> > >         https://www.mipi.org/specifications/mipi-disco-imaging
> >
> > OK
> >
> > > > Co-developed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > > > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > > ---
> > > >  drivers/acpi/internal.h |    1
> > > >  drivers/acpi/mipi-di.c  |  240 +++++++++++++++++++++++++++++++++++++++++++++++-
> > >
> > > How about mipi-disco.c? I wouldn't mind having mipi-disco-imaging.c either.
> >
> > Well, mipi-disco-imaging is a bit too long and the meaning of
> > mipi-disco would not be clear IMO.
> >
> > What about mipi-disco-img?
>
> Seems fine to me.
>
> >
> > [cut]
> >
> > > > +     ret = fwnode_property_count_u8(port_fwnode, "mipi-img-lane-polarities");
> > > > +     if (ret > 0) {
> > > > +             unsigned long mask;
> > > > +             unsigned int i;
> > > > +
> > > > +             /*
> > > > +              * Total number of lanes here is clock lane + data lanes.
> > > > +              * Require that number to be low enough so they all can be
> > > > +              * covered by the bits in one byte.
> > > > +              */
> > > > +             BUILD_BUG_ON(BITS_PER_TYPE(u8) <= ARRAY_SIZE(port->data_lanes));
> > > > +
> > > > +             fwnode_property_read_u8_array(port_fwnode,
> > > > +                                           "mipi-img-lane-polarities",
> > > > +                                           val, 1);
> > > > +
> > > > +             for (mask = val[0], i = 0; i < num_lanes + 1; i++)
> > > > +                     port->lane_polarities[i] = test_bit(i, &mask);
> > >
> > > This works only up to seven lanes.
> >
> > True, but then ACPI_DEVICE_CSI2_DATA_LANES is defined as 4.
>
> The spec has no limit and in practice 4 is relatively common while 8 exists
> (but is somewhat rare). I actually think it'd be a good idea to bump this
> to 8 already.

OK