[PATCH 2/2] of: search the best compatible match first in __of_match_node()
Stephen N Chivers
schivers at csc.com.au
Sat Feb 15 16:19:01 EST 2014
Rob Herring <robherring2 at gmail.com> wrote on 02/15/2014 02:53:40 AM:
> From: Rob Herring <robherring2 at gmail.com>
> To: Kevin Hao <haokexin at gmail.com>
> Cc: "devicetree at vger.kernel.org" <devicetree at vger.kernel.org>,
> linuxppc-dev <linuxppc-dev at lists.ozlabs.org>, Sebastian Hesselbarth
> <sebastian.hesselbarth at gmail.com>, Stephen N Chivers
> <schivers at csc.com.au>, Grant Likely <grant.likely at linaro.org>, Rob
> Herring <robh+dt at kernel.org>, Kumar Gala <galak at codeaurora.org>
> Date: 02/15/2014 02:53 AM
> Subject: Re: [PATCH 2/2] of: search the best compatible match first
> in __of_match_node()
>
> On Thu, Feb 13, 2014 at 11:22 PM, Kevin Hao <haokexin at gmail.com> wrote:
> > Currently, of_match_node compares each given match against all node's
> > compatible strings with of_device_is_compatible.
> >
> > To achieve multiple compatible strings per node with ordering from
> > specific to generic, this requires given matches to be ordered from
> > specific to generic. For most of the drivers this is not true and also
> > an alphabetical ordering is more sane there.
> >
> > Therefore, this patch introduces a function to match each of the
node's
> > compatible strings against all given compatible matches without type
and
> > name first, before checking the next compatible string. This implies
> > that node's compatibles are ordered from specific to generic while
> > given matches can be in any order. If we fail to find such a match
> > entry, then fall-back to the old method in order to keep
compatibility.
> >
> > Cc: Sebastian Hesselbarth <sebastian.hesselbarth at gmail.com>
> > Signed-off-by: Kevin Hao <haokexin at gmail.com>
>
> Looks good to me. I'll put this in next for a few days. I'd really
> like to see some acks and tested-by's before sending to Linus.
>
Tested-by: Stephen Chivers <schivers at csc.com>
I have tested the patch for the four PowerPC platforms
available to me.
They are:
MPC8349_MITXGP - Works.
MVME5100 - Works.
MVME4100 - Works.
SAM440EP - Works.
The MPC8349_MITXGP platform is present in Linux-3.13 and previous
releases.
The MVME5100 is a "revived" platform that is in Linux-3.14-rc2.
The MVME4100 is a work in progress and is the 85xx platform that the
original failure report was for.
The SAM440EP is present in Linux-3.13 and previous releases.
The MPC8349_MITXGP is one of the 49 DTS files with the serial compatible:
compatible = "fsl,ns16550", "ns16550";
For the SAM440EP, the patch improves things from Linux-3.13. In that
release the same sort of problem as reported in:
"Linux-3.14-rc2: Order of serial node compatibles in DTS files."
occurs with slightly different symptoms:
of_serial ef600300.serial: Port found
of_serial ef600300.serial: Port found
of_serial ef600300.serial: Unknown serial port found, ignored
of_serial ef600400.serial: Port found
of_serial ef600400.serial: Port found
of_serial ef600400.serial: Unknown serial port found, ignored
of_serial ef600500.serial: Port found
of_serial ef600500.serial: Port found
of_serial ef600500.serial: Unknown serial port found, ignored
of_serial ef600600.serial: Port found
of_serial ef600600.serial: Port found
of_serial ef600600.serial: Unknown serial port found, ignored
The SAM440EP has a IBM/AMCC 440EP PowerPC CPU and so simply has
"ns16550" as its serial compatible.
> We could be a bit more strict here and fallback to the old matching if
> the match table has any entries with name or type. I don't think that
> should be necessary though.
>
> Rob
Stephen Chivers,
CSC Australia Pty. Ltd.
>
> > ---
> > drivers/of/base.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 42 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/of/base.c b/drivers/of/base.c
> > index ba195fbce4c6..10b51106c854 100644
> > --- a/drivers/of/base.c
> > +++ b/drivers/of/base.c
> > @@ -730,13 +730,49 @@ out:
> > }
> > EXPORT_SYMBOL(of_find_node_with_property);
> >
> > +static const struct of_device_id *
> > +of_match_compatible(const struct of_device_id *matches,
> > + const struct device_node *node)
> > +{
> > + const char *cp;
> > + int cplen, l;
> > + const struct of_device_id *m;
> > +
> > + cp = __of_get_property(node, "compatible", &cplen);
> > + while (cp && (cplen > 0)) {
> > + m = matches;
> > + while (m->name[0] || m->type[0] || m->compatible[0]) {
> > + /* Only match for the entries without type
> and name */
> > + if (m->name[0] || m->type[0] ||
> > + of_compat_cmp(m->compatible, cp,
> > + strlen(m->compatible)))
> > + m++;
> > + else
> > + return m;
> > + }
> > +
> > + /* Get node's next compatible string */
> > + l = strlen(cp) + 1;
> > + cp += l;
> > + cplen -= l;
> > + }
> > +
> > + return NULL;
> > +}
> > +
> > static
> > const struct of_device_id *__of_match_node(const struct
> of_device_id *matches,
> > const struct device_node
*node)
> > {
> > + const struct of_device_id *m;
> > +
> > if (!matches)
> > return NULL;
> >
> > + m = of_match_compatible(matches, node);
> > + if (m)
> > + return m;
> > +
> > while (matches->name[0] || matches->type[0] ||
> matches->compatible[0]) {
> > int match = 1;
> > if (matches->name[0])
> > @@ -760,7 +796,12 @@ const struct of_device_id *__of_match_node
> (const struct of_device_id *matches,
> > * @matches: array of of device match structures to search
in
> > * @node: the of device structure to match against
> > *
> > - * Low level utility function used by device matching.
> > + * Low level utility function used by device matching. We have
two ways
> > + * of matching:
> > + * - Try to find the best compatible match by comparing each
compatible
> > + * string of device node with all the given matches
respectively.
> > + * - If the above method failed, then try to match the
> compatible by using
> > + * __of_device_is_compatible() besides the match in type and
name.
> > */
> > const struct of_device_id *of_match_node(const struct
> of_device_id *matches,
> > const struct device_node
*node)
> > --
> > 1.8.5.3
> >
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