Re: [PATCH v3 2/4] irqchip/qcom-pdc: Switch to using IRQCHIP_PLATFORM_DRIVER helper macros

[Marc Zyngier]

On 2020-08-06 02:24, John Stultz wrote:
> On Wed, Aug 5, 2020 at 1:19 PM Saravana Kannan <saravanak@xxxxxxxxxx> 
> wrote:
> > On Wed, Aug 5, 2020 at 12:44 AM John Stultz <john.stultz@xxxxxxxxxx> 
> > wrote:
> > > On Fri, Jul 17, 2020 at 5:06 PM Saravana Kannan <saravanak@xxxxxxxxxx> wrote:
> > > >
> > > > Switch the driver to use the helper macros. In addition to reducing the
> > > > number of lines, this also adds module unload protection (if the driver
> > > > is compiled as a module) by switching from module_platform_driver to
> > > > builtin_platform_driver.
> > > >
> > > > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> > > > ---
> > > >  drivers/irqchip/qcom-pdc.c | 26 +++-----------------------
> > > >  1 file changed, 3 insertions(+), 23 deletions(-)
> > > >
> > > > diff --git a/drivers/irqchip/qcom-pdc.c b/drivers/irqchip/qcom-pdc.c
> > > > index 5b624e3295e4..c1c5dfad57cc 100644
> > > > --- a/drivers/irqchip/qcom-pdc.c
> > > > +++ b/drivers/irqchip/qcom-pdc.c
> > > > @@ -432,28 +432,8 @@ static int qcom_pdc_init(struct device_node *node, struct device_node *parent)
> > > >         return ret;
> > > >  }
> > > >
> > > > -static int qcom_pdc_probe(struct platform_device *pdev)
> > > > -{
> > > > -       struct device_node *np = pdev->dev.of_node;
> > > > -       struct device_node *parent = of_irq_find_parent(np);
> > > > -
> > > > -       return qcom_pdc_init(np, parent);
> > > > -}
> > > > -
> > > > -static const struct of_device_id qcom_pdc_match_table[] = {
> > > > -       { .compatible = "qcom,pdc" },
> > > > -       {}
> > > > -};
> > > > -MODULE_DEVICE_TABLE(of, qcom_pdc_match_table);
> > > > -
> > > > -static struct platform_driver qcom_pdc_driver = {
> > > > -       .probe = qcom_pdc_probe,
> > > > -       .driver = {
> > > > -               .name = "qcom-pdc",
> > > > -               .of_match_table = qcom_pdc_match_table,
> > > > -               .suppress_bind_attrs = true,
> > > > -       },
> > > > -};
> > > > -module_platform_driver(qcom_pdc_driver);
> > > > +IRQCHIP_PLATFORM_DRIVER_BEGIN(qcom_pdc)
> > > > +IRQCHIP_MATCH("qcom,pdc", qcom_pdc_init)
> > > > +IRQCHIP_PLATFORM_DRIVER_END(qcom_pdc)
> > > >  MODULE_DESCRIPTION("Qualcomm Technologies, Inc. Power Domain Controller");
> > > >  MODULE_LICENSE("GPL v2");
> > >
> > > <sigh>
> > > So this is where I bashfully admit I didn't get a chance to try this
> > > patch series out, as I had success with a much older version of
> > > Saravana's macro magic.
> > >
> > > But unfortunately, now that this has landed in mainline, I'm seeing
> > > boot regressions on db845c. :( This is in the non-modular case,
> > > building the driver in.
> >
> > Does that mean the modular version is working? Or you haven't tried
> > that yet? I'll wait for your reply before I try to fix it. I don't
> > have the hardware, but it should be easy to guess this issue looking
> > at the code delta.
>
> I've not yet tested with modules with your patch.
>
> > The only significant change from what your probe function is doing is
> > this snippet. But it'd be surprising if this only affects the builtin
> > case.
> >
> > + if (par_np == np)
> > +         par_np = NULL;
> > +
> > + /*
> > + * If there's a parent interrupt controller and  none of the parent 
> > irq
> > + * domains have been registered, that means the parent interrupt
> > + * controller has not been initialized yet.  it's not time for this
> > + * interrupt controller to initialize. So, defer probe of this
> > + * interrupt controller. The actual initialization callback of this
> > + * interrupt controller can check for specific domains as necessary.
> > + */
> > + if (par_np && !irq_find_matching_host(np, DOMAIN_BUS_ANY))
> > +         return -EPROBE_DEFER;
>
> Yep. We're getting caught on the irq_find_matching_host() check. I'm a
> little lost as when I look at the qcom,pdc node in the dtsi its not
> under a parent controller (instead the soc node).
> Not sure if that's an issue in the dtsi or if par_np check needs to
> ignore the soc node and pass null?

I think you have nailed it. This checks for a domain attached to
the driver we are about to probe, and this domain cannot possibly
exist. Instead, it is the *parent* this should check for, as we
depend on it for successful probing.

Can you please give this a go?

Thanks,

        M.

diff --git a/drivers/irqchip/irqchip.c b/drivers/irqchip/irqchip.c
index 1bb0e36c2bf3..d2341153e181 100644
--- a/drivers/irqchip/irqchip.c
+++ b/drivers/irqchip/irqchip.c
@@ -52,7 +52,7 @@ int platform_irqchip_probe(struct platform_device 
*pdev)
 	 * interrupt controller. The actual initialization callback of this
 	 * interrupt controller can check for specific domains as necessary.
 	 */
-	if (par_np && !irq_find_matching_host(np, DOMAIN_BUS_ANY))
+	if (par_np && !irq_find_matching_host(par_np, DOMAIN_BUS_ANY))
 		return -EPROBE_DEFER;

 	return irq_init_cb(np, par_np);

--
Jazz is not dead. It just smells funny...