Re: [PATCH 4/4] perf: arm_spe: Enable ACPI/Platform automatic module loading

From: Will Deacon
Date: Tue Apr 16 2019 - 09:51:07 EST


On Thu, Apr 04, 2019 at 12:24:38PM -0500, Jeremy Linton wrote:
> On 4/4/19 12:04 PM, Will Deacon wrote:
> > On Tue, Mar 26, 2019 at 05:39:38PM -0500, Jeremy Linton wrote:
> > > Lets add the MODULE_TABLE and platform id_table entries so that
> > > the SPE driver can attach to the ACPI platform device created by
> > > the core pmu code.
> > >
> > > Signed-off-by: Jeremy Linton <jeremy.linton@xxxxxxx>
> > > Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> > > ---
> > > drivers/perf/arm_spe_pmu.c | 11 +++++++++--
> > > 1 file changed, 9 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
> > > index 7cb766dafe85..ffa2c76c08bb 100644
> > > --- a/drivers/perf/arm_spe_pmu.c
> > > +++ b/drivers/perf/arm_spe_pmu.c
> > > @@ -1176,7 +1176,13 @@ static const struct of_device_id arm_spe_pmu_of_match[] = {
> > > };
> > > MODULE_DEVICE_TABLE(of, arm_spe_pmu_of_match);
> > > -static int arm_spe_pmu_device_dt_probe(struct platform_device *pdev)
> > > +static const struct platform_device_id arm_spe_match[] = {
> > > + { "arm,spe-v1", 0},
> >
> > It would be nice if we could avoid duplicating this string from the ACPI
> > parsing code.
>
> Ok sure, I just need to find a good common place for it.
>
> >
> > > + { }
> > > +};
> > > +MODULE_DEVICE_TABLE(platform, arm_spe_match);
> > > +
> > > +static int arm_spe_pmu_device_probe(struct platform_device *pdev)
> > > {
> > > int ret;
> > > struct arm_spe_pmu *spe_pmu;
> > > @@ -1236,11 +1242,12 @@ static int arm_spe_pmu_device_remove(struct platform_device *pdev)
> > > }
> > > static struct platform_driver arm_spe_pmu_driver = {
> > > + .id_table = arm_spe_match,
> > > .driver = {
> > > .name = DRVNAME,
> > > .of_match_table = of_match_ptr(arm_spe_pmu_of_match),
> >
> > Hmm, so some other drivers don't hook .id_table like you do, but instead
> > hook .acpi_match_table in the driver structure. Is that not better?
>
> This isn't actually an ACPI device, (aka not defined in the namespace), so
> its missing much of the ACPI functionality. I think that also means its
> needs to be declared this way.

Looking at platform_match(), I'd really like to avoid having both an
.id_table and an .of_match_table field.

acpi_of_match_device() will actually use the .of_match_table, but it relies
on ACPI_COMPANION returning a valid acpi_device. If we don't have one of
those, perhaps we can use the .id_table exclusively and drop the
.of_match_table instead?

Will