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From:   nikita.shubin@maquefel.me
To:     Mathieu Poirier <mathieu.poirier@linaro.org>,
        Nikita Shubin <nshubin@topcon.com>
Cc:     Ohad Ben-Cohen <ohad@wizery.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        linux-remoteproc <linux-remoteproc@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
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Subject: Re: [PATCH 1/2] remoteproc: imx_rproc: dummy kick method
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Date:   Thu, 05 Mar 2020 20:29:50 +0300
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05.03.2020, 19:17, "Mathieu Poirier" <mathieu.poirier@linaro.org>:
> On Wed, 4 Mar 2020 at 07:25, Nikita Shubin <NShubin@topcon.com> wrote:
>>  add kick method that does nothing, to avoid errors in rproc_virtio_notify.
>>
>>  Signed-off-by: Nikita Shubin <NShubin@topcon.com>
>>  ---
>>   drivers/remoteproc/imx_rproc.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>>  diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
>>  index 3e72b6f38d4b..796b6b86550a 100644
>>  --- a/drivers/remoteproc/imx_rproc.c
>>  +++ b/drivers/remoteproc/imx_rproc.c
>>  @@ -240,9 +240,15 @@ static void *imx_rproc_da_to_va(struct rproc *rproc, u64 da, int len)
>>          return va;
>>   }
>>
>>  +static void imx_rproc_kick(struct rproc *rproc, int vqid)
>>  +{
>>  +
>>  +}
>>  +
>
> If rproc::kick() is empty, how does the MCU know there is packets to
> fetch in the virtio queues?

Well, of course it doesn't i understand this perfectly - just following documentation citing:

| Every remoteproc implementation should at least provide the ->start and ->stop
| handlers. If rpmsg/virtio functionality is also desired, then the ->kick handler
| should be provided as well.

But i as i mentioned in "remoteproc: Fix NULL pointer dereference in rproc_virtio_notify" kick method will be called if 
"resource_table exists in firmware and has "Virtio device entry" defined" anyway, the imx_rproc is not in control of what 
exactly it is booting, so such situation can occur.

>
>>   static const struct rproc_ops imx_rproc_ops = {
>>          .start = imx_rproc_start,
>>          .stop = imx_rproc_stop,
>>  + .kick = imx_rproc_kick,
>>          .da_to_va = imx_rproc_da_to_va,
>>   };
>>
>>  --
>>  2.24.1