linux-kernel - Re: [PATCH V1 14/15] spmi: pmic-arb: do not ack and clear peripheral interrupts in cleanup

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Date:   Tue, 18 Jul 2017 17:23:07 +0530
From:   kgunda@...eaurora.org
To:     Stephen Boyd <sboyd@...eaurora.org>
Cc:     Abhijeet Dharmapurikar <adharmap@...eaurora.org>,
        David Collins <collinsd@...eaurora.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Subbaraman Narayanamurthy <subbaram@...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 14/15] spmi: pmic-arb: do not ack and clear peripheral
 interrupts in cleanup_irq

On 2017-06-13 07:40, Stephen Boyd wrote:
> On 06/06, kgunda@...eaurora.org wrote:
>> On 2017-06-02 12:56, kgunda@...eaurora.org wrote:
>> >On 2017-05-31 23:23, Stephen Boyd wrote:
>> >>On 05/30, Kiran Gunda wrote:
>> >>>From: Subbaraman Narayanamurthy <subbaram@...eaurora.org>
>> >>>
>> >>>Currently, cleanup_irq() is invoked when a peripheral's interrupt
>> >>>fires and there is no mapping present in the interrupt domain of
>> >>>spmi interrupt controller.
>> >>>
>> >>>The cleanup_irq clears the arbiter bit, clears the pmic interrupt
>> >>>and disables it at the pmic in that order. The last disable in
>> >>>cleanup_irq races with request_irq() in that it stomps over the
>> >>>enable issued by request_irq. Fix this by not writing to the pmic
>> >>>in cleanup_irq. The latched bit will be left set in the pmic,
>> >>>which will not send us more interrupts even if the enable bit
>> >>>stays enabled.
>> >>>
>> >>>When a client wants to request an interrupt, use the activate
>> >>>callback on the irq_domain to clear latched bit. This ensures
>> >>>that the latched, if set due to the above changes in cleanup_irq
>> >>>or when the bootloader leaves it set, gets cleaned up, paving way
>> >>>for upcoming interrupts to trigger.
>> >>>
>> >>>With this, there is a possibility of unwanted triggering of
>> >>>interrupt right after the latched bit is cleared - the interrupt
>> >>>may be left enabled too. To avoid that, clear the enable first
>> >>>followed by clearing the latched bit in the activate callback.
>> >>>
>> >>>Signed-off-by: Subbaraman Narayanamurthy <subbaram@...eaurora.org>
>> >>>Signed-off-by: Kiran Gunda <kgunda@...eaurora.org>
>> >>
>> >>Please squash this with the patch that adds cleanup_irq() and
>> >>rewrite the commit text to combine details from both.
>> >Sure. Will squash it in the next patch submission.
>> Patch that adds cleanup_irq is already taken in to the tree.
>> Lets have this patch as is now.
> 
> Is this the one with the kbuild error? IRQ domains are not always
> there, so I don't know how this is expected to work.
Dropped out this patch as it is related to clearing the interrupts those 
are left enabled
by the boot loader. We thought of clearing all the apps owned interrupts 
in the UEFI itself.