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From:   Moritz Fischer <moritz.fischer@ettus.com>
Date:   Sun, 9 Sep 2018 12:20:09 -0700
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Subject: Re: [PATCH v11 03/11] firmware: xilinx: Add zynqmp IOCTL API for
 device control
To:     Olof Johansson <olof@lixom.net>
Cc:     Jolly Shah <jolly.shah@xilinx.com>,
        "ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
        Ingo Molnar <mingo@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        matt@codeblueprint.co.uk, Sudeep Holla <sudeep.holla@arm.com>,
        hkallweit1@gmail.com, Kees Cook <keescook@chromium.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@codeaurora.org>,
        Michal Simek <michal.simek@xilinx.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        linux-clk <linux-clk@vger.kernel.org>, rajanv@xilinx.com,
        Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>, Jolly Shah <jollys@xilinx.com>
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Hi Olof,

On Sat, Sep 8, 2018 at 6:18 PM, Olof Johansson <olof@lixom.net> wrote:
> Hi,
>
> On Fri, Aug 3, 2018 at 10:53 AM, Jolly Shah <jolly.shah@xilinx.com> wrote:
>> From: Rajan Vaja <rajanv@xilinx.com>
>>
>> Add ZynqMP firmware IOCTL API to control and configure
>> devices like PLLs, SD, Gem, etc.
>>
>> Signed-off-by: Rajan Vaja <rajanv@xilinx.com>
>> Signed-off-by: Jolly Shah <jollys@xilinx.com>
>
> This patch worries me somewhat. It's a transparent pass-through ioctl
> driver. Is there a spec available for what the implemented IOCTLs are?
>
> Should some of them be proper drivers instead of an opaque
> pass-through like this? Could some of them have stability impact on
> the platform such that there are security concerns and the list of
> arguments should somehow be sanitized?

I tend to agree with this, good catch.

> What's the intended usecase anyway? Just a debug tool during
> development, or something that you expect heavy use of by some
> userspace middleware?

I suspect it is another attempt to make userspace clocks/plls work? Scary.

Cheers,
Moritz