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[68.147.8.254]) by smtp.gmail.com with ESMTPSA id y186sm6934pfy.66.2020.05.05.15.03.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 15:03:29 -0700 (PDT) Date: Tue, 5 May 2020 16:03:27 -0600 From: Mathieu Poirier To: Arnaud POULIQUEN Cc: bjorn.andersson@linaro.org, ohad@wizery.com, loic.pallardy@st.com, s-anna@ti.com, linux-remoteproc@vger.kernel.org, corbet@lwn.net, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 10/14] remoteproc: Deal with synchronisation when shutting down Message-ID: <20200505220327.GB18333@xps15> References: <20200424200135.28825-1-mathieu.poirier@linaro.org> <20200424200135.28825-11-mathieu.poirier@linaro.org> <20200430202312.GE17031@xps15> <04b8f860-2b01-7e4f-cdea-08a3cf8af26c@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <04b8f860-2b01-7e4f-cdea-08a3cf8af26c@st.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-remoteproc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org On Mon, May 04, 2020 at 01:34:43PM +0200, Arnaud POULIQUEN wrote: > > > On 4/30/20 10:23 PM, Mathieu Poirier wrote: > > On Wed, Apr 29, 2020 at 10:19:49AM +0200, Arnaud POULIQUEN wrote: > >> > >> > >> On 4/24/20 10:01 PM, Mathieu Poirier wrote: > >>> The remoteproc core must not allow function rproc_shutdown() to > >>> proceed if currently synchronising with a remote processor and > >>> the synchronisation operations of that remote processor does not > >>> support it. Also part of the process is to set the synchronisation > >>> flag so that the remoteproc core can make the right decisions when > >>> restarting the system. > >>> > >>> Signed-off-by: Mathieu Poirier > >>> --- > >>> drivers/remoteproc/remoteproc_core.c | 32 ++++++++++++++++++++++++ > >>> drivers/remoteproc/remoteproc_internal.h | 7 ++++++ > >>> 2 files changed, 39 insertions(+) > >>> > >>> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c > >>> index 3a84a38ba37b..48afa1f80a8f 100644 > >>> --- a/drivers/remoteproc/remoteproc_core.c > >>> +++ b/drivers/remoteproc/remoteproc_core.c > >>> @@ -1849,6 +1849,27 @@ int rproc_boot(struct rproc *rproc) > >>> } > >>> EXPORT_SYMBOL(rproc_boot); > >>> > >>> +static bool rproc_can_shutdown(struct rproc *rproc) > >>> +{ > >>> + /* > >>> + * The remoteproc core is the lifecycle manager, no problem > >>> + * calling for a shutdown. > >>> + */ > >>> + if (!rproc_needs_syncing(rproc)) > >>> + return true; > >>> + > >>> + /* > >>> + * The remoteproc has been loaded by another entity (as per above > >>> + * condition) and the platform code has given us the capability > >>> + * of stopping it. > >>> + */ > >>> + if (rproc->sync_ops->stop) > >>> + return true; > >> > >> This means that if rproc->sync_ops->stop is null rproc_stop_subdevices will not > >> be called? seems not symmetric with the start sequence. > > > > If rproc->sync_ops->stop is not provided then the remoteproc core can't stop the > > remote processor at all after it has synchronised with it. If a usecase > > requires some kind of soft reset then a stop() function that uses a mailbox > > notification or some other mechanism can be provided to tell the remote > > processor to put itself back in startup mode again. > > > > Is this fine with you or there is still something I don't get? > > My point here is more around the subdevices. But perhaps i missed something... > > In rproc_start rproc_start_subdevices is called, even if sync_start is null. Here I'll take that you mean sync_ops::start() > But in rproc_shutdown rproc_stop is not called, if sync_ops->stop is null. > So rproc_stop_subdevices is not called in this case. Correct. I am pretty sure some people don't want the remoteproc core to be able to do anything other than synchronise with a remote processor, be it at boot time or when the remote processor has crashed. I can also see scenarios where people want to be able to start and stop subdevices from the remoteproc core, but _not_ power cycle the remote processor. In such cases the sync_ops::stop() should be some kind of notification telling the remote processor to put itself back in initialisation mode and sync_flags.after_stop should be set to true. > Then if sync_flags.after_stop is false, it looks like that something will go wrong > at next start. If sync_ops::stop is NULL then the value of sync_flags.after_stop becomes irrelevant because that state can't be reached. Let me know if you found a condition where this isn't the case and I will correct it. > > > > >> Probably not useful to test it here as condition is already handled in rproc_stop_device... > >> > >> Regards > >> Arnaud > >>> + > >>> + /* Any other condition should not be allowed */ > >>> + return false; > >>> +} > >>> + > >>> /** > >>> * rproc_shutdown() - power off the remote processor > >>> * @rproc: the remote processor > >>> @@ -1879,6 +1900,9 @@ void rproc_shutdown(struct rproc *rproc) > >>> return; > >>> } > >>> > >>> + if (!rproc_can_shutdown(rproc)) > >>> + goto out; > >>> + > >>> /* if the remote proc is still needed, bail out */ > >>> if (!atomic_dec_and_test(&rproc->power)) > >>> goto out; > >>> @@ -1898,6 +1922,14 @@ void rproc_shutdown(struct rproc *rproc) > >>> kfree(rproc->cached_table); > >>> rproc->cached_table = NULL; > >>> rproc->table_ptr = NULL; > >>> + > >>> + /* > >>> + * The remote processor has been switched off - tell the core what > >>> + * operation to use from hereon, i.e whether an external entity will > >>> + * reboot the remote processor or it is now the remoteproc core's > >>> + * responsability. > >>> + */ > >>> + rproc_set_sync_flag(rproc, RPROC_SYNC_STATE_SHUTDOWN); > >>> out: > >>> mutex_unlock(&rproc->lock); > >>> } > >>> diff --git a/drivers/remoteproc/remoteproc_internal.h b/drivers/remoteproc/remoteproc_internal.h > >>> index 61500981155c..7dcc0a26892b 100644 > >>> --- a/drivers/remoteproc/remoteproc_internal.h > >>> +++ b/drivers/remoteproc/remoteproc_internal.h > >>> @@ -27,6 +27,9 @@ struct rproc_debug_trace { > >>> /* > >>> * enum rproc_sync_states - remote processsor sync states > >>> * > >>> + * @RPROC_SYNC_STATE_SHUTDOWN state to use after the remoteproc core > >>> + * has shutdown (rproc_shutdown()) the > >>> + * remote processor. > >>> * @RPROC_SYNC_STATE_CRASHED state to use after the remote processor > >>> * has crashed but has not been recovered by > >>> * the remoteproc core yet. > >>> @@ -36,6 +39,7 @@ struct rproc_debug_trace { > >>> * operation to use. > >>> */ > >>> enum rproc_sync_states { > >>> + RPROC_SYNC_STATE_SHUTDOWN, > >>> RPROC_SYNC_STATE_CRASHED, > >>> }; > >>> > >>> @@ -43,6 +47,9 @@ static inline void rproc_set_sync_flag(struct rproc *rproc, > >>> enum rproc_sync_states state) > >>> { > >>> switch (state) { > >>> + case RPROC_SYNC_STATE_SHUTDOWN: > >>> + rproc->sync_with_rproc = rproc->sync_flags.after_stop; > >>> + break; > >>> case RPROC_SYNC_STATE_CRASHED: > >>> rproc->sync_with_rproc = rproc->sync_flags.after_crash; > >>> break; > >>>