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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Tue, 27 Aug 2019 16:14:54 +0200
Message-ID: <CAK8P3a1WBkmXbJx=rZMumxn7EN4bmA1AdZEgrWBVyQ3XNngU6Q@mail.gmail.com>
Subject: Re: [PATCH 6/7] misc: bcm-vk: add Broadcom Valkyrie driver
To:     Scott Branden <scott.branden@broadcom.com>
Cc:     Luis Chamberlain <mcgrof@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        David Brown <david.brown@linaro.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Shuah Khan <shuah@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Shuah Khan <skhan@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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        Kees Cook <keescook@chromium.org>,
        Takashi Iwai <tiwai@suse.de>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        Desmond Yan <desmond.yan@broadcom.com>,
        James Hu <james.hu@broadcom.com>,
        Linux Media Mailing List <linux-media@vger.kernel.org>,
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On Thu, Aug 22, 2019 at 9:25 PM Scott Branden
<scott.branden@broadcom.com> wrote:
>
> Add Broadcom Valkyrie driver offload engine.
> This driver interfaces to the Valkyrie PCIe offload engine to perform
> should offload functions as video transcoding on multiple streams
> in parallel.  Valkyrie device is booted from files loaded using
> request_firmware_into_buf mechanism.  After booted card status is updated
> and messages can then be sent to the card.
> Such messages contain scatter gather list of addresses
> to pull data from the host to perform operations on.
>
> Signed-off-by: Scott Branden <scott.branden@broadcom.com>
> Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
> Signed-off-by: James Hu <james.hu@broadcom.com>

Can you explain the decision to make this is a standalone misc driver
rather than hooking into the existing framework in drivers/media?

There is an existing interface that looks like it could fit the hardware
in include/media/v4l2-mem2mem.h. Have you considered using that?

There is also support for video transcoding using GPUs in
driver/gpu/drm/, that could also be used in theory, though it sounds
like a less optimal fit.

      Arnd