Re: [PATCH v3 1/1] remoteproc: add support for co-processor loaded and booted before kernel

From: Mathieu Poirier
Date: Fri Nov 15 2019 - 16:13:03 EST

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In reply to: Loic PALLARDY: "RE: [PATCH v3 1/1] remoteproc: add support for co-processor loaded and booted before kernel"
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On Fri, 15 Nov 2019 at 08:27, Loic PALLARDY <loic.pallardy@xxxxxx> wrote:
>
> Hi Mathieu,
>
> > -----Original Message-----
> > From: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > Sent: jeudi 14 novembre 2019 19:19
> > To: Loic PALLARDY <loic.pallardy@xxxxxx>
> > Cc: bjorn.andersson@xxxxxxxxxx; ohad@xxxxxxxxxx; linux-
> > remoteproc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Arnaud
> > POULIQUEN <arnaud.pouliquen@xxxxxx>; benjamin.gaignard@xxxxxxxxxx;
> > Fabien DESSENNE <fabien.dessenne@xxxxxx>; s-anna@xxxxxx
> > Subject: Re: [PATCH v3 1/1] remoteproc: add support for co-processor
> > loaded and booted before kernel
> >
> > Hi Loic,
> >
> > On Wed, Nov 13, 2019 at 10:29:03PM +0100, Loic Pallardy wrote:
> > > 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@xxxxxx>
> > >
> > > ---
> > > Change from v2:
> > > - rename property into skip_fw_load
> > > - update rproc_boot and rproc_fw_boot description
> > > - update commit message
> > > Change from v1:
> > > - Keep bool in struct rproc
> > > ---
> > > drivers/remoteproc/remoteproc_core.c | 51
> > +++++++++++++++++++++++++++---------
> > > include/linux/remoteproc.h | 2 ++
> > > 2 files changed, 40 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/remoteproc/remoteproc_core.c
> > b/drivers/remoteproc/remoteproc_core.c
> > > index 3c5fbbbfb0f1..585cdca8b241 100644
> > > --- a/drivers/remoteproc/remoteproc_core.c
> > > +++ b/drivers/remoteproc/remoteproc_core.c
> > > @@ -1360,7 +1360,7 @@ static int rproc_start(struct rproc *rproc, const
> > struct firmware *fw)
> > > }
> > >
> > > /*
> > > - * take a firmware and boot a remote processor with it.
> > > + * Handle resources defined in resource table and start a remote
> > processor.
> > > */
> > > static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
> > > {
> > > @@ -1372,7 +1372,11 @@ 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");
> >
> > Here we assume that if @fw is NULL then the image is already loaded. The
> > first
> > question that comes to mind is if that means the ELF image has already been
> > copied to the coprocessor's boot address. If that is the case it would be nice
> > to make it explicit with a comment in the code.
>
> Yes, but will be better to test "skip_fw_load" properties to change display info message.

I am good with the different dev_info() based on the value of @fw.

> Anyway, agree to mention that if @fw is NULL that means fw considered as already loaded.

If you have to do a respin then a clear explanation would be
appreciated, especially since this is core code. If you don't go for
a 4th iteration then leave it as is.

> >
> > Following the earlier comments made on the thread for this serie, I
> > understand
> > the rproc_ops fed to the core should provision for @fw being NULL. In
> > this case though st_rproc_ops[1] reference a number of core operations that
> > aren't tailored to handled a NULL @fw parameter.
>
> True, some patches will follow
>
> >
> > I am pretty sure you're well aware of this and you have more patches to go
> > with
> > this one or said patches have already been published and I'm looking at the
> > wrong tree. If that is the case would you mind making those patches public or
> > pointing me to a repository somewhere?
>
> Please have a look here [1].
> The properties is named preloaded instead of skip_fw_load, but that's the same.

I saw rproc::early_boot but the end result is indeed the same.

> Impacted ops are working differently according to preloaded status.
>
> When skip_fw_load is true, no ELF image is used. Platform driver is in charge of providing resource table location somewhere in memory.
> Somewhere is platform dependent.

Thanks for letting me in on the bigger picture - things are much
clearer now and I see where you're going. How the resource table is
handled in stm32_rproc_elf_load_rsc_table() also answers my questions
in that area.

Acked-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>

>
> Regards,
> Loic
> [1] https://github.com/STMicroelectronics/linux/blob/v4.19-stm32mp/drivers/remoteproc/stm32_rproc.c
>
> >
> > I have other concerns about the specifics shared between the application
> > and co
> > processors using the ELF image but I'll wait for your reply to the above before
> > addressing those.
> >
> > Regards,
> > Mathieu
> >
> > [1]. https://elixir.bootlin.com/linux/v5.4-
> > rc7/source/drivers/remoteproc/stm32_rproc.c#L470
> >
> > >
> > > /*
> > > * if enabling an IOMMU isn't relevant for this rproc, this is
> > > @@ -1719,16 +1723,22 @@ 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;
> > >
> > > @@ -1759,11 +1769,17 @@ 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 to null as unknown */
> > > + kfree(rproc->firmware);
> > > + rproc->firmware = NULL;
> > > }
> > >
> > > ret = rproc_fw_boot(rproc, firmware_p);
> > > @@ -1917,8 +1933,17 @@ 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 */
> > > 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;
> > > };
> > > --
> > > 2.7.4
> > >

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In reply to: Loic PALLARDY: "RE: [PATCH v3 1/1] remoteproc: add support for co-processor loaded and booted before kernel"
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