linux-kernel - Re: [PATCH 1/2] remoteproc: imx

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Date:   Thu, 05 Mar 2020 21:46:26 +0300
From:   nikita.shubin@...uefel.me
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     Nikita Shubin <nshubin@...con.com>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-remoteproc <linux-remoteproc@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] remoteproc: imx_rproc: dummy kick method

That's totally okay - thank you for review.

05.03.2020, 21:36, "Mathieu Poirier" <mathieu.poirier@...aro.org>:
> On Thu, 5 Mar 2020 at 11:07, <nikita.shubin@...uefel.me> wrote:
>>  05.03.2020, 20:54, "Mathieu Poirier" <mathieu.poirier@...aro.org>:
>>  > On Thu, 5 Mar 2020 at 10:29, <nikita.shubin@...uefel.me> wrote:
>>  >> 05.03.2020, 19:17, "Mathieu Poirier" <mathieu.poirier@...aro.org>:
>>  >> > On Wed, 4 Mar 2020 at 07:25, Nikita Shubin <NShubin@...con.com> wrote:
>>  >> >> add kick method that does nothing, to avoid errors in rproc_virtio_notify.
>>  >> >>
>>  >> >> Signed-off-by: Nikita Shubin <NShubin@...con.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.
>>  >
>>  > If I understand correctly, the MCU can boot images that have a virtio
>>  > device in its resource table and still do useful work even if the
>>  > virtio device/rpmsg bus can't be setup - is this correct?
>>
>>  Yes, this assumption is correct.
>>
>>  Despite this situation is not i desire at all - such thing can happen.
>>  I am currently using co-proc as a realtime part of UGV control,
>>  so it must immediately stop the engines, if not provided with navigational information.
>>
>>  The imx7d MCU have access to the most periphery that have the main processor.
>>
>>  Of course the kick method should do real work, but i decided to submit step by step if i am allowed to do so.
>
> Ok, the situation is clearer now and I have put your patches back in
> my queue. I am seriously back-logged at this time so it will take a
> little while before I get to them.
>
>>  >
>>  > Thanks,
>>  > Mathieu
>>  >
>>  >> >
>>  >> >> 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