linux-kernel - Re: [PATCH V1 05/15] spmi: pmic-arb: cleanup unrequested irqs

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Date:   Mon, 12 Jun 2017 19:11:34 -0700
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     kgunda@...eaurora.org
Cc:     Abhijeet Dharmapurikar <adharmap@...eaurora.org>,
        Subbaraman Narayanamurthy <subbaram@...eaurora.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        David Collins <collinsd@...eaurora.org>,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        adharmap@...cinc.com, aghayal@....qualcomm.com,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH V1 05/15] spmi: pmic-arb: cleanup unrequested irqs

On 06/06, kgunda@...eaurora.org wrote:
> On 2017-05-31 07:27, Stephen Boyd wrote:
> >On 05/30, Kiran Gunda wrote:
> >>From: Abhijeet Dharmapurikar <adharmap@...eaurora.org>
> >>
> >>We see a unmapped irqs trigger right around bootup. This could
> >>likely be because the bootloader exited leaving the interrupts
> >>in an unknown or unhandled state.  Ack and mask the interrupt
> >>if one is found. A request_irq later will unmask it and also
> >>setup proper mapping structures.
> >
> >Do we have systems where this is causing an interrupt storm due
> >to a level high interrupt or something? Just plain acking and
> >masking irqs at boot if we don't have an irq descriptor created
> >yet doesn't sound like a good idea, because we'll lose all
> >interrupts that happen before this driver probes?
> >
> Yes. There were instances of an interrupt storm without this patch.
> There is an RT_STATUS register in the  peripheral address space which
> maintains the real time state and can be read by the client driver
> before it registers for the irq. Few client drivers such as charger
> already doing this.

So you're saying that drivers need to read RT_STATUS to know if
they have a pending interrupt before requesting it? That sounds
bogus.

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