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SubjectRE: [PATCH v5 1/3] remoteproc: add support for co-processor loaded and booted before kernel
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> Subject: Re: [PATCH v5 1/3] remoteproc: add support for co-processor loaded
> and booted before kernel
>
> On Thu, 20 Feb 2020 at 14:40, Mathieu Poirier <mathieu.poirier@linaro.org>
> wrote:
> >
> > On Thu, 20 Feb 2020 at 02:35, Arnaud POULIQUEN
> <arnaud.pouliquen@st.com> wrote:
> > >
> > >
> > >
> > > On 2/19/20 9:56 PM, Mathieu Poirier wrote:
> > > > Hey Arnaud,
> > > >
> > > > On Tue, 18 Feb 2020 at 10:31, Arnaud POULIQUEN
> <arnaud.pouliquen@st.com> wrote:
> > > >>
> > > >> Hi Mathieu, Bjorn,
> > > >>
> > > >> On 2/17/20 7:40 PM, Mathieu Poirier wrote:
> > > >>> On Fri, 14 Feb 2020 at 09:33, Arnaud POULIQUEN
> <arnaud.pouliquen@st.com> wrote:
> > > >>>>
> > > >>>> Hi Mathieu,
> > > >>>>
> > > >>>> On 2/13/20 9:08 PM, Mathieu Poirier wrote:
> > > >>>>> Good day,
> > > >>>>>
> > > >>>>> On Tue, Feb 11, 2020 at 06:42:03PM +0100, Arnaud Pouliquen
> wrote:
> > > >>>>>> From: Loic Pallardy <loic.pallardy@st.com>
> > > >>>>>>
> > > >>>>>> Remote processor could boot independently or be
> > > >>>>>> loaded/started before Linux kernel by bootloader or any
> firmware.
> > > >>>>>> This patch introduces a new property in rproc core, named
> > > >>>>>> skip_fw_load, to be able to allocate resources and
> > > >>>>>> sub-devices like vdev and to synchronize with current state
> without loading firmware from file system.
> > > >>>>>> It is platform driver responsibility to implement the right
> > > >>>>>> firmware load ops according to HW specificities.
> > > >>>>>>
> > > >>>>>> Signed-off-by: Loic Pallardy <loic.pallardy@st.com>
> > > >>>>>> Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> > > >>>>>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
> > > >>>>>> ---
> > > >>>>>> drivers/remoteproc/remoteproc_core.c | 67
> ++++++++++++++++++++++------
> > > >>>>>> include/linux/remoteproc.h | 2 +
> > > >>>>>> 2 files changed, 55 insertions(+), 14 deletions(-)
> > > >>>>>>
> > > >>>>>> diff --git a/drivers/remoteproc/remoteproc_core.c
> > > >>>>>> b/drivers/remoteproc/remoteproc_core.c
> > > >>>>>> index 097f33e4f1f3..876b5420a32b 100644
> > > >>>>>> --- a/drivers/remoteproc/remoteproc_core.c
> > > >>>>>> +++ b/drivers/remoteproc/remoteproc_core.c
> > > >>>>>> @@ -1358,8 +1358,19 @@ static int rproc_start(struct rproc
> *rproc, const struct firmware *fw)
> > > >>>>>> return ret;
> > > >>>>>> }
> > > >>>>>>
> > > >>>>>> -/*
> > > >>>>>> - * take a firmware and boot a remote processor with it.
> > > >>>>>> +/**
> > > >>>>>> + * rproc_fw_boot() - boot specified remote processor
> > > >>>>>> +according to specified
> > > >>>>>> + * firmware
> > > >>>>>> + * @rproc: handle of a remote processor
> > > >>>>>> + * @fw: pointer on firmware to handle
> > > >>>>>> + *
> > > >>>>>> + * Handle resources defined in resource table, load firmware
> > > >>>>>> +and
> > > >>>>>> + * start remote processor.
> > > >>>>>> + *
> > > >>>>>> + * If firmware pointer fw is NULL, firmware is not handled
> > > >>>>>> +by remoteproc
> > > >>>>>> + * core, but under the responsibility of platform driver.
> > > >>>>>> + *
> > > >>>>>> + * Returns 0 on success, and an appropriate error value
> otherwise.
> > > >>>>>> */
> > > >>>>>> static int rproc_fw_boot(struct rproc *rproc, const struct
> > > >>>>>> firmware *fw) { @@ -1371,7 +1382,11 @@ static int
> > > >>>>>> rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
> > > >>>>>> if (ret)
> > > >>>>>> return ret;
> > > >>>>>>
> > > >>>>>> - dev_info(dev, "Booting fw image %s, size %zd\n", name,
> fw->size);
> > > >>>>>> + if (fw)
> > > >>>>>> + dev_info(dev, "Booting fw image %s, size %zd\n",
> name,
> > > >>>>>> + fw->size);
> > > >>>>>> + else
> > > >>>>>> + dev_info(dev, "Synchronizing with preloaded
> > > >>>>>> + co-processor\n");
> > > >>>>>>
> > > >>>>>> /*
> > > >>>>>> * if enabling an IOMMU isn't relevant for this rproc,
> > > >>>>>> this is @@ -1718,16 +1733,22 @@ static void
> rproc_crash_handler_work(struct work_struct *work)
> > > >>>>>> * rproc_boot() - boot a remote processor
> > > >>>>>> * @rproc: handle of a remote processor
> > > >>>>>> *
> > > >>>>>> - * Boot a remote processor (i.e. load its firmware, power it
> on, ...).
> > > >>>>>> + * Boot a remote processor (i.e. load its firmware, power it
> > > >>>>>> + on, ...) from
> > > >>>>>> + * different contexts:
> > > >>>>>> + * - power off
> > > >>>>>> + * - preloaded firmware
> > > >>>>>> + * - started before kernel execution
> > > >>>>>> + * The different operations are selected thanks to
> > > >>>>>> + properties defined by
> > > >>>>>> + * platform driver.
> > > >>>>>> *
> > > >>>>>> - * If the remote processor is already powered on, this
> > > >>>>>> function immediately
> > > >>>>>> - * returns (successfully).
> > > >>>>>> + * If the remote processor is already powered on at rproc
> > > >>>>>> + level, this function
> > > >>>>>> + * immediately returns (successfully).
> > > >>>>>> *
> > > >>>>>> * Returns 0 on success, and an appropriate error value
> otherwise.
> > > >>>>>> */
> > > >>>>>> int rproc_boot(struct rproc *rproc) {
> > > >>>>>> - const struct firmware *firmware_p;
> > > >>>>>> + const struct firmware *firmware_p = NULL;
> > > >>>>>> struct device *dev;
> > > >>>>>> int ret;
> > > >>>>>>
> > > >>>>>> @@ -1758,11 +1779,20 @@ int rproc_boot(struct rproc *rproc)
> > > >>>>>>
> > > >>>>>> dev_info(dev, "powering up %s\n", rproc->name);
> > > >>>>>>
> > > >>>>>> - /* load firmware */
> > > >>>>>> - ret = request_firmware(&firmware_p, rproc->firmware,
> dev);
> > > >>>>>> - if (ret < 0) {
> > > >>>>>> - dev_err(dev, "request_firmware failed: %d\n",
> ret);
> > > >>>>>> - goto downref_rproc;
> > > >>>>>> + if (!rproc->skip_fw_load) {
> > > >>>>>> + /* load firmware */
> > > >>>>>> + ret = request_firmware(&firmware_p,
> rproc->firmware, dev);
> > > >>>>>> + if (ret < 0) {
> > > >>>>>> + dev_err(dev, "request_firmware
> failed: %d\n", ret);
> > > >>>>>> + goto downref_rproc;
> > > >>>>>> + }
> > > >>>>>> + } else {
> > > >>>>>> + /*
> > > >>>>>> + * Set firmware name pointer to null as
> remoteproc core is not
> > > >>>>>> + * in charge of firmware loading
> > > >>>>>> + */
> > > >>>>>> + kfree(rproc->firmware);
> > > >>>>>> + rproc->firmware = NULL;
> > > >>>>>
> > > >>>>> If the MCU with pre-loaded FW crashes request_firmware() in
> > > >>>>> rproc_trigger_recovery() will return an error and
> > > >>>>> rproc_start() never called.
> > > >>>>
> > > >>>> Right, something is missing in the recovery function to prevent
> > > >>>> request_firmware call if skip_fw_load is set
> > > >>>>
> > > >>>> We also identify an issue if recovery fails:
> > > >>>> In case of recovery issue the rproc state is RPROC_CRASHED, so
> > > >>>> that it is no more possible to load a new firmware from user space.
> > > >>>> This issue is not linked to this patchset. We have patches on our
> shelves for this.
> > > >>>>
> > > >>>>>> }
> > > >>>>>>
> > > >>>>>> ret = rproc_fw_boot(rproc, firmware_p); @@ -1916,8
> > > >>>>>> +1946,17 @@ int rproc_add(struct rproc *rproc)
> > > >>>>>> /* create debugfs entries */
> > > >>>>>> rproc_create_debug_dir(rproc);
> > > >>>>>>
> > > >>>>>> - /* if rproc is marked always-on, request it to boot */
> > > >>>>>> - if (rproc->auto_boot) {
> > > >>>>>> + if (rproc->skip_fw_load) {
> > > >>>>>> + /*
> > > >>>>>> + * If rproc is marked already booted, no need to
> wait
> > > >>>>>> + * for firmware.
> > > >>>>>> + * Just handle associated resources and start sub
> devices
> > > >>>>>> + */
> > > >>>>>> + ret = rproc_boot(rproc);
> > > >>>>>> + if (ret < 0)
> > > >>>>>> + return ret;
> > > >>>>>> + } else if (rproc->auto_boot) {
> > > >>>>>> + /* if rproc is marked always-on, request it to
> > > >>>>>> + boot */
> > > >>>>>
> > > >>>>> I spent way too much time staring at this modification... I
> > > >>>>> can't decide if a system where the FW has been pre-loaded should
> be considered "auto_boot".
> > > >>>>> Indeed the result is the same, i.e the MCU is started at boot
> > > >>>>> time without user intervention.
> > > >>>>
> > > >>>> The main difference is that the firmware is loaded by the Linux
> remote proc in case of auto-boot.
> > > >>>> In auto-boot mode the remoteproc loads a firmware, on probe, with
> a specified name without any request from user space.
> > > >>>> One constraint of this mode is that the file system has to be
> accessible before the rproc probe.
> > > >>>
> > > >>> Indeed, but in both cases the MCU is booted automatically. In
> > > >>> one case the FW is loaded by the framework and in the other it
> > > >>> is not. As such both scenarios are "auto_boot", they simply
> > > >>> have different flavours.
> > > >> Regarding your concerns i would like to propose an alternative that will
> answer to following use cases:
> > > >>
> > > >> In term of use cases we can start the remote proc firmware in following
> modes:
> > > >> - auto boot with FW loading, resource table parsing and FW
> > > >> start/stop
> > > >> - auto boot without FW loading, with FW resource table parsing
> > > >> and FW start/stop
> > > >> - auto boot with FW attachment and resource table parsing
> > > >> - boot on userspace request with FW loading, resource table
> > > >> parsing and FW start/stop
> > > >> - boot on userspace request without FW loading, with FW resource
> > > >> table parsing and FW start/stop
> > > >> - boot on userspace request with FW attachment and resource
> > > >> table parsing
> > > >>
> > > >> I considered the recovery covered by these use cases...
> > > >>
> > > >> I tried to concatenate all use case to determine the behavior of the core
> and platform driver:
> > > >> - "auto-boot" used to decide if boot is from driver or user space
> > > >> request (independently from fw loading and live cycle management)
> > > >> - "skip_fw_load" allows to determine if a firmware has to be loaded or
> not.
> > > >> - remote Firmware live cycle (start,stop,...) are managed by the
> platform driver, it would have to determine the manage the remote proc
> depending on the mode detected.
> > > >>
> > > >> If i apply this for stm32mp1 driver:
> > > >> normal boot( FW started on user space request):
> > > >> - auto-boot = 0
> > > >> - skip_fw_load = 0
> > > >> FW loaded and started by the bootloader
> > > >> - auto-boot = 1
> > > >> - skip_firmware = 1;
> > > >>
> > > >> => on a stop: the "auto-boot" and "skip_firmware flag will be reset by
> the stm32rproc driver, to allow user space to load a new firmware or reste
> the system.
> > > >> this is considered as a ack by Bjorn today, if you have an alternative
> please share.
> > > >
> > > > I wonder if we can achieve the same results without needing
> > > > rproc::skip_fw_load... For cases where the FW would have been
> > > > loaded and the MCU started by another entity we could simply set
> > > > rproc->state = RPROC_RUNNING in the platform driver. That way
> > > > when the MCU is stopped or crashes, there is no flag to reset,
> > > > rproc->state is simply set correctly by the current code.
> > > >
> > > > I would also set auto_boot =1 in order to start the AP
> > > > synchronisation as quickly as possible and add a check in
> > > > rproc_trigger_auto_boot() to see if rproc->state == RPROC_RUNNING.
> > > > If so simply call rproc_boot() where platform specific rproc_ops
> > > > would be tailored to handle a running processor.
> > >
> > > Your proposal is interesting, what concerns me is that seems to work
> > > only for a first start.
> >
> > Correct, my proposal will skip loading the MCU firmware only when
> > Linux boots and MCU probed. I thought this was what your patchset is
> > doing.
> >
> > > And calling rproc_boot, while state is RPROC_RUNNING seems pretty
> > > strange for me.
> >
> > After sending my email I thought about spinning off a new function,
> > something like rproc_sync() and call it instead of rproc_boot(). But
> > none of that matters now that Peng has highlighted the need to handle
> > late attach scenarios where the FW is never loaded by the remoteproc
> > core.
> >
> > > Also, as Peng mentions in
> > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpa
> > >
> tchwork.kernel.org%2Fpatch%2F11390485%2F&amp;data=02%7C01%7Cpen
> g.fan
> > > %40nxp.com%7C648ac45834db4c39759308d7bb1ff410%7C686ea1d3bc2
> b4c6fa92c
> > >
> d99c5c301635%7C0%7C0%7C637183618236375559&amp;sdata=Lc54HlLqjd
> e0WLmU
> > > Zp27s9JVic6IQTqt%2BKDaCYfQDGo%3D&amp;reserved=0,
> > > the need also exists to skip the load of the firmware on recovery.
> > > How to manage ROM/XIP Firmwares, no handling of the FW code only
> > > management of the live cycle (using sysfs, crash management ....)?
> > >
> >
> > A very good question, and something I need to think about after
> > reviewing Peng's patchset. I will get back to you.
>
> After reviewing Peng's patches it became clear to me using if/else statements
> will quickly become unmanageable - we need something flexible that can
> scale. After spending a long time looking at what TI, NXP and ST have done
> to address their specific needs I think a solution is starting to take shape in my
> head. From here I think the best way to proceed is for me to write a
> patchset that enacts those ideas and sent it out for review, something that
> should take me around
> 2 weeks.

Thanks for working on this. Looking forward your patches, then I'll rebase
my patches and give a test.

Thanks,
Peng.

>
> >
> > > >
> > > > In my opinion the above would represent the state of the MCU
> > > > rather than the state of the FW used by the MCU. It would also
> > > > provide an opening for supporting systems where the MCU is not the
> > > > life cycle manager.
> > > Not sure to catch your point here. By "above" you mention your proposal
> or mine?
> >
> > I was talking about the lines I wrote.
> >
> > > In my opinion, rproc->state already represents the MCU state what
> > > seems missing is the FW state Could you clarify what you mean by
> > > "systems where the MCU is not the life cycle manager" MCU = rproc
> > > framework?
> >
> > Arrgghh... That's a brain bug on my side. It should have been AP, not MCU.
> >
> > >
> > > Regards
> > > Arnaud
> > >
> > > >
> > > > Let me know what you think...
> > > >
> > > >>
> > > >> I need to rework the patchset in consequence but i would appreciate
> your feedback on this proposal before, to be sure that i well interpreted your
> concerns...
> > > >>
> > > >> Regards,
> > > >> Arnaud
> > > >>
> > > >>>
> > > >>>> This is not necessary the case, even if EPROBE_DEFER is used. In this
> case the driver has to be build as kernel module.
> > > >>>>
> > > >>>> Thanks,
> > > >>>> Arnaud
> > > >>>>>
> > > >>>>> I'd welcome other people's opinion on this.
> > > >>>>>
> > > >>>>>> ret = rproc_trigger_auto_boot(rproc);
> > > >>>>>> if (ret < 0)
> > > >>>>>> return ret; diff --git
> > > >>>>>> a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > > >>>>>> index 16ad66683ad0..4fd5bedab4fa 100644
> > > >>>>>> --- a/include/linux/remoteproc.h
> > > >>>>>> +++ b/include/linux/remoteproc.h
> > > >>>>>> @@ -479,6 +479,7 @@ struct rproc_dump_segment {
> > > >>>>>> * @table_sz: size of @cached_table
> > > >>>>>> * @has_iommu: flag to indicate if remote processor is behind
> an MMU
> > > >>>>>> * @auto_boot: flag to indicate if remote processor should
> > > >>>>>> be auto-started
> > > >>>>>> + * @skip_fw_load: remote processor has been preloaded before
> > > >>>>>> + start sequence
> > > >>>>>> * @dump_segments: list of segments in the firmware
> > > >>>>>> * @nb_vdev: number of vdev currently handled by rproc
> > > >>>>>> */
> > > >>>>>> @@ -512,6 +513,7 @@ struct rproc {
> > > >>>>>> size_t table_sz;
> > > >>>>>> bool has_iommu;
> > > >>>>>> bool auto_boot;
> > > >>>>>> + bool skip_fw_load;
> > > >>>>>> struct list_head dump_segments;
> > > >>>>>> int nb_vdev;
> > > >>>>>> };
> > > >>>>>> --
> > > >>>>>> 2.17.1
> > > >>>>>>
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