linux-kernel - Re: [RESEND PATCH] gpio: omap: Fix lost edge interrupts

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Date:   Sat, 7 Oct 2017 19:34:14 -0700
From:   "santosh.shilimkar@...cle.com" <santosh.shilimkar@...cle.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Grygorii Strashko <grygorii.strashko@...com>
Cc:     Tony Lindgren <tony@...mide.com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ladislav Michl <ladis@...ux-mips.org>
Subject: Re: [RESEND PATCH] gpio: omap: Fix lost edge interrupts

On 10/7/17 4:18 AM, Linus Walleij wrote:
> On Tue, Oct 3, 2017 at 6:17 PM, Grygorii Strashko
> <grygorii.strashko@...com> wrote:
> 
>> Now acking of edge irqs happens the following way:
>> - omap_gpio_irq_handler
>>    - "isr" = read irq status
>>    - omap_clear_gpio_irqbank(bank, isr_saved & ~level_mask);
>>          ^ clear edge status, so irq can be accepted
>>    - loop while "isr"
>>          generic_handle_irq()
>>           - handle_edge_irq()
>>              - desc->irq_data.chip->irq_ack(&desc->irq_data);
>>                  - omap_gpio_ack_irq()
>> it might be that at this moment edge IRQ was triggered again and it will be
>> cleared and IRQ will be lost.
>>
>> Use handle_simple_irq and clear edge interrupts early without disabling them in
>> omap_gpio_irq_handler to avoid loosing interrupts.
>>
>> [1] https://urldefense.proofpoint.com/v2/url?u=https-3A__marc.info_-3Fl-3Dlinux-2Domap-26m-3D149004465313534-26w-3D2&d=DwIBaQ&c=RoP1YumCXCgaWHvlZYR8PQcxBKCX5YTpkKY057SbK10&r=XBn1JQGPwR8CsE7xpP3wPlG6DQU7qw8ym65xieNZ4hY&m=GC9UD4RPcq1Ss-JanXn4japAFhT1w4RZlq9WqDLSw_o&s=smHFYjIN3O5THK4qP413bHMnr8PaWUv4xyUbbTwXHk4&e=

This link doesn't need to be part of the changelog.

>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>> Signed-off-by: Ladislav Michl <ladis@...ux-mips.org>
> 
> Patch applied for fixes.
> 
> I guess it is the right thing to do?
> 
> Other maintainers need to tell me if I should hold it back.
> 
Am fine with it after Grygorii's reasoning.

Regards,
Santosh