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Date:   Fri, 21 Feb 2020 13:47:38 +0100 (CET)
From:   Jiri Kosina <jikos@kernel.org>
To:     "Shah, Nehal-bakulchandra" <nehal-bakulchandra.shah@amd.com>
cc:     Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Sandeep Singh <Sandeep.Singh@amd.com>,
        lkml <linux-kernel@vger.kernel.org>,
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        Jonathan Cameron <jic23@kernel.org>, linux-iio@vger.kernel.org,
        Shyam-sundar.S-k@amd.com
Subject: Re: [PATCH v3 0/5] SFH: Add Support for AMD Sensor Fusion Hub
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On Wed, 19 Feb 2020, Shah, Nehal-bakulchandra wrote:

> > 2 problems here:
> > - patch 3/5 references this debugfs interface which is only added in 4/5.
> > - you are creating a new sysfs set of file for debug purpose only, but
> > as soon as we start shipping those, some other people will find it
> > more convenient to use that directly instead or IIO, and you won't be
> > able to change anything there.
> >
> > So I would strongly advocate against having this debugfs, and suggest you to:
> > - either keep this debugfs as a downstream patch
> > - either play with eBPF or kprobes to retrieve the same information
> > without changing the kernel.
> >
> > For reference, I recently tried to replicate the hidraw functionality
> > with eBPF[0] without changing the kernel code, and it was working.
> > Well, there was no filtering on the source of the HID event, but
> > still, I got the same data directly from the kernel just by adding
> > instrumentation in a couple of functions.

Wow. Complete eBPF supremacy is really coming shortly apparently :)

> If Jiri is Ok, then we will push the next patch as per suggestion here 
> i.e. taking out debugfs.

I agree with that. Thanks,

-- 
Jiri Kosina
SUSE Labs