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Date:   Wed, 30 Nov 2022 08:30:51 +0100
From:   Lukas Wunner <lukas@wunner.de>
To:     Keith Busch <kbusch@kernel.org>
Cc:     Bjorn Helgaas <helgaas@kernel.org>, linux-pci@vger.kernel.org,
        Alex Williamson <alex.williamson@redhat.com>,
        Amey Narkhede <ameynarkhede03@gmail.com>,
        Ashok Raj <ashok.raj@intel.com>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Ravi Kishore Koppuravuri <ravi.kishore.koppuravuri@intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: Re: [PATCH] PCI/DPC: Add Software Trigger as reset method
Message-ID: <20221130073051.GA8198@wunner.de>
References: <9c1533fd42e9002bd6d2020656fa1dd0e3e3bf3a.1669706952.git.lukas@wunner.de>
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On Tue, Nov 29, 2022 at 09:36:33AM -0700, Keith Busch wrote:
> On Tue, Nov 29, 2022 at 08:35:55AM +0100, Lukas Wunner wrote:
> > Add DPC Software Trigger as a reset method to be used for silicon
> > validation among other things:
> 
> Do you really need a kernel helper to do this? You can test these with
> 
>   # setpci -s <dsp's b:d.f> ECAP_DPC+6.w=40:40
> 
> And since the kernel is a not aware you are synthesizing the DPC event,
> that more naturally tests how the kernel would react to a hardware dpc
> trigger.

I've seen people write a value directly instead of using the "data:mask"
syntax above and that's dangerous because the register is under the
control of the kernel.

By exposing software trigger as a reset method I hope to make its
invocation error-proof and more comfortable.

Thanks,

Lukas