From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Loic PALLARDY Subject: RE: [RFC 1/2] remoteproc: sysfs: authorize rproc shutdown when rproc is crashed Date: Wed, 25 Mar 2020 18:30:28 +0000 Message-ID: <9a089cba07f7454ea0fc0f2d09bd9bf0@SFHDAG7NODE2.st.com> References: <1583924072-20648-1-git-send-email-loic.pallardy@st.com> <1583924072-20648-2-git-send-email-loic.pallardy@st.com> <20200325175746.GA6227@xps15> In-Reply-To: <20200325175746.GA6227@xps15> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 To: Mathieu Poirier Cc: "bjorn.andersson@linaro.org" , "ohad@wizery.com" , "linux-remoteproc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Arnaud POULIQUEN , "benjamin.gaignard@linaro.org" , "Fabien DESSENNE , s-anna@ti.com" List-ID: Hi Mathieu, > -----Original Message----- > From: Mathieu Poirier > Sent: mercredi 25 mars 2020 18:58 > To: Loic PALLARDY > Cc: bjorn.andersson@linaro.org; ohad@wizery.com; linux- > remoteproc@vger.kernel.org; linux-kernel@vger.kernel.org; Arnaud > POULIQUEN ; benjamin.gaignard@linaro.org; > Fabien DESSENNE ; s-anna@ti.com > Subject: Re: [RFC 1/2] remoteproc: sysfs: authorize rproc shutdown when > rproc is crashed >=20 > Hi Loic, >=20 > On Wed, Mar 11, 2020 at 11:54:31AM +0100, Loic Pallardy wrote: > > When remoteproc recovery is disabled and rproc crashed, user space > > client has no way to reboot co-processor except by a complete platform > > reboot. > > Indeed rproc_shutdown() is called by sysfs state_store() only is rproc > > state is RPROC_RUNNING. > > > > This patch offers the possibility to shutdown the co-processor if > > it is in RPROC_CRASHED state and so to restart properly co-processor > > from sysfs interface. >=20 > If recovery is disabled on an rproc the platform likely intended to have = a hard > reboot and as such we should not be concerned about this case. I disagree with your view. In fact, we can have a configuration for which we don't want a silent recovery. Application layer can be involved to stop = and restart some services because it is the simplest way to resync with the cop= rocessor. What's missing today is an event to notify user space application that copr= ocessor state has changed. (even if we can rely on rpmsg services closure) >=20 > Where I think we have a problem, something that is asserted by looking at > your 2 > patches, is cases where rproc_trigger_recovery() fails. That leaves the > system > in a state where it can't be recovered, something the remoteproc core > should not > allow. >=20 Right this is a second use case we faced when user space application which = provided firmware file crashed before coprocessor. In that case firmware file may be= removed from /lib/firmware directory and coprocessor recovery failed. Application, when restarting, can't anymore control coprocessor. Regards, Loic > > > > Signed-off-by: Loic Pallardy > > --- > > drivers/remoteproc/remoteproc_core.c | 2 +- > > drivers/remoteproc/remoteproc_sysfs.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/remoteproc/remoteproc_core.c > b/drivers/remoteproc/remoteproc_core.c > > index 097f33e4f1f3..7ac87a75cd1b 100644 > > --- a/drivers/remoteproc/remoteproc_core.c > > +++ b/drivers/remoteproc/remoteproc_core.c > > @@ -1812,7 +1812,7 @@ void rproc_shutdown(struct rproc *rproc) > > if (!atomic_dec_and_test(&rproc->power)) > > goto out; > > > > - ret =3D rproc_stop(rproc, false); > > + ret =3D rproc_stop(rproc, rproc->state =3D=3D RPROC_CRASHED); >=20 > Please add a comment that explains how we can be in rproc_shutdown() > when the > processor has crashed and point to rproc_trigger_recovery(). See below f= or > more > details. >=20 > > if (ret) { > > atomic_inc(&rproc->power); > > goto out; > > diff --git a/drivers/remoteproc/remoteproc_sysfs.c > b/drivers/remoteproc/remoteproc_sysfs.c > > index 7f8536b73295..1029458a4678 100644 > > --- a/drivers/remoteproc/remoteproc_sysfs.c > > +++ b/drivers/remoteproc/remoteproc_sysfs.c > > @@ -101,7 +101,7 @@ static ssize_t state_store(struct device *dev, > > if (ret) > > dev_err(&rproc->dev, "Boot failed: %d\n", ret); > > } else if (sysfs_streq(buf, "stop")) { > > - if (rproc->state !=3D RPROC_RUNNING) > > + if (rproc->state !=3D RPROC_RUNNING && rproc->state !=3D > RPROC_CRASHED) > > return -EINVAL; >=20 > Wouldn't it be better to just prevent the MCU to stay in a crashed state > (when > recovery is not disabled)? >=20 > I like what you did in the next patch where the state of the MCU is set t= o > RPROC_CRASHED in case of failure, so that we keep. I also think the hunk > above is correct. All that is left is to call rproc_shutdown() directly = in > rproc_trigger_recovery() when something goes wrong. I would also add a > dev_err() so that users have a clue of what happened. >=20 > That would leave the system in a stable state without having to add > intelligence > to state_store(). It is a solution we debate internally. Should rproc_shutdown() called direc= tly in rproc_trigger_recovery() or not? If we go in such direction, that clearly s= implify=20 coprocessor control as it will always be in a "stable" state. But that mean= s user will lost information that coprocessor crashed (mainly when recovery is dis= abled). We just know that coprocessor is stopped but not why? Crashed or client act= ion?=20 For debug purpose, it could be an issue from my pov. Regards, Loic >=20 > Let me know that you think... >=20 > Mathieu >=20 > > > > rproc_shutdown(rproc); > > -- > > 2.7.4 > >