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

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Date:   Fri, 02 Jun 2017 12:56:26 +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 2017-05-31 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.