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From:   Thomas Gleixner <tglx@linutronix.de>
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To:     Marc Zyngier <maz@kernel.org>
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Subject: Re: [patch V2 43/46] genirq/msi: Provide and use msi_domain_set_default_info_flags()
In-Reply-To: <b80607e87e43730133dd9f619c6464dc@kernel.org>
References: <20200826111628.794979401@linutronix.de> <20200826112334.889315931@linutronix.de> <b80607e87e43730133dd9f619c6464dc@kernel.org>
Date:   Fri, 28 Aug 2020 20:42:21 +0200
Message-ID: <87zh6ek3xu.fsf@nanos.tec.linutronix.de>
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On Thu, Aug 27 2020 at 09:17, Marc Zyngier wrote:
> On 2020-08-26 12:17, Thomas Gleixner wrote:
>>  #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
>> +void msi_domain_set_default_info_flags(struct msi_domain_info *info)
>> +{
>> +	/* Required so that a device latches a valid MSI message on startup 
>> */
>> +	info->flags |= MSI_FLAG_ACTIVATE_EARLY;
>
> As far as I remember the story behind this flag (it's been a while),
> it was working around a PCI-specific issue, hence being located in
> the PCI code.

Yes. Some cards misbehave when there is no valid message programmed and
MSI is enabled.

> Now, the "program the MSI before enabling it" concept makes sense no
> matter what bus this is on, and I wonder why we are even keeping this
> flag around.

> Can't we just drop it together with the check in
> msi_domain_alloc_irqs()?

I'm fine with that.

Thanks,

        tglx