linux-kernel - RE: [PATCH] usb: gadget: udc: renesas_usb3: Fix RZ/V2M {modprobe,bind} error

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Date:   Mon, 29 May 2023 10:03:27 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Marc Zyngier <maz@...nel.org>
CC:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Zheng Wang <zyytlz.wz@....com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
Subject: RE: [PATCH] usb: gadget: udc: renesas_usb3: Fix RZ/V2M
 {modprobe,bind} error

Hi Marc Zyngier,

Thanks for the feedback.

> Subject: Re: [PATCH] usb: gadget: udc: renesas_usb3: Fix RZ/V2M
> {modprobe,bind} error
> 
> On Mon, 29 May 2023 10:39:50 +0100,
> Biju Das <biju.das.jz@...renesas.com> wrote:
> >
> > Hi Marc Zyngier,
> >
> > Thanks for the feedback.
> >
> > > Subject: Re: [PATCH] usb: gadget: udc: renesas_usb3: Fix RZ/V2M
> > > {modprobe,bind} error
> > >
> > > On Mon, 29 May 2023 09:42:34 +0100,
> > > Biju Das <biju.das.jz@...renesas.com> wrote:
> > > >
> > > > Hi Laurent,
> > > >
> > > > Thanks for the feedback.
> > > >
> > > > > Subject: Re: [PATCH] usb: gadget: udc: renesas_usb3: Fix RZ/V2M
> > > > > {modprobe,bind} error
> > > > >
> > > > > Hi Biju,
> > > > >
> > > > > Thank you for the patch.
> > > > >
> > > > > On Fri, May 26, 2023 at 03:36:15PM +0100, Biju Das wrote:
> > > > > > Currently {modprobe, bind} after {rmmod, unbind} results in
> > > > > > probe
> > > > > failure.
> > > > > >
> > > > > > genirq: Flags mismatch irq 22. 00000004 (85070400.usb3drd) vs.
> > > > > > 00000004 (85070400.usb3drd)
> > > > > > renesas_usb3: probe of 85070000.usb3peri failed with error -16
> > > > > >
> > > > > > Fix this issue by replacing "parent dev"->"dev" as the irq
> > > > > > resource is managed by this driver.
> > > > >
> > > > > If the dev pointer passed to devm_request_irq() is not the
> > > > > correct one, how does it work the first time the driver is
> loaded ?
> > > >
> > > > + Marc/ Kernel.org to give some feedback on this issue
> > > >
> > > > I believe there may be a bug in the genirq (kernel/irq) driver.
> > > > first time it works ok. Maybe this driver is caching on unload
> > > > with null value and comparing with actual one (irq 22) during
> reload??
> > > >
> > > > Maybe genirq expert can comment what went wrong here??
> > >
> > > You get shouted at because you are registering an interrupt handler
> > > for the same IRQ twice,
> >
> > This not true. It is registering only one IRQ, but with parent device
> handle.
> 
> And you're doing that *TWICE*. Once per load of this driver.

I got it from Laurent's feedback.

> 
> >
> >  and the interrupt is not configured with the SHARED
> > > flag.
> >
> > I haven't added SHARED flag as there is only one IRQ registration.
> >
> >  If, as I understand it, you only have a single device using this
> > > interrupt, then it means your driver is not freeing its interrupt on
> > > unload.
> >
> > You mean devm_request_irq(ddata->dev..)  doesn't free the resource as
> > we have unloaded only child device rather than parent.
> >
> > But while parent is active, why genirq is giving error during reload?
> > It should show same behaviour like initial probe.
> 
> Do you understand the meaning of the "dev" parameter you pass to
> devm_request_irq()?

Yes, the resource is managed with particular device.

I should not use devm_request_irq here. rather should use
request_irq and free_irq during unload with parent device handle.

Cheers,
Biju