[PATCH 2/2] remoteproc: imx_dsp_rproc: add module parameter to ignore ready flag from remote processor
Mathieu Poirier
mathieu.poirier at linaro.org
Wed Jul 19 08:47:21 PDT 2023
On Tue, Jul 18, 2023 at 07:44:49PM +0300, Iuliana Prodan wrote:
> On 7/18/2023 6:48 PM, Mathieu Poirier wrote:
> > On Tue, Jul 18, 2023 at 11:30:43AM +0300, Iuliana Prodan wrote:
> > > Hi Mathieu,
> > >
> > > On 7/17/2023 8:34 PM, Mathieu Poirier wrote:
> > > > Hi Iuliana,
> > > >
> > > > On Thu, Jul 13, 2023 at 01:42:51AM +0300, Iuliana Prodan (OSS) wrote:
> > > > > From: Iuliana Prodan <iuliana.prodan at nxp.com>
> > > > >
> > > > > There are cases when we want to test samples that do not
> > > > > reply with FW READY message, after fw is loaded and the
> > > > > remote processor started.
> > > > This seems like a bug to me - where is this FW comes from?
> > > The firmware is a generic sample from Zephyr repo: https://github.com/zephyrproject-rtos/zephyr/tree/main/samples/subsys/ipc/openamp_rsc_table
> > >
> > > There is no bug, this is how the application was written.
> > But how did it ever worked before?
>
> It never worked on this kind of samples (and it was never tested like this).
> We used only applications written by us (NXP) with the
> requirements/limitations we know we have.
> Now, we want to use also generic firmware/samples (from Zephyr) and we face
> other kind of limitations.
>
Right, we can't expect firmware written for a totally different OS to work out
of the box on Linux, and vice versa.
> > And how does having a module flag to
> > characterize each FW implementation that springs up in the field can scale (and
> > be maintainable)?
>
> I believe the FW_READY reply is a limitation introduced by imx_dsp_rproc.
> We cannot expect all firmware to give a FW_READY reply.
> So, to keep both usecases (internal firmware and generic sample) I added
> this flag.
>
What happens when a third, fourth and fifth protocol variation get introduced?
Adding flags just doesn't scale.
> > > Rather than modifying a generic sample for i.MX usecase, I prefer doing an
> > > "insmod imx_dsp_rproc.ko ignore_dsp_ready=1" just for this sample.
> > We already have a "no_mailbox" flag for cases where the FW doesn't need to
> > communicate with the main processor.
> "no_mailbox" - no IPC between cores;
> "ignore_dsp_ready" - we have IPC between cores, but the remote processor
> doesn't send a fw_ready reply
> These two can be combine, but for "no_mailbox" will do some useless memory
> allocations.
>
> When I added the "no_mailbox" flag, the problem was still FW_READY.
> > What happens when some FW implementation
> > requires a three-way handshake? How many flags do we spin off?
> >
> > As I said above this approach is not sustainable. I suggest to either fix the
> > FW (it doesn't work with upstream in its present form anyway) or start using the
> > config space as described here [1] to dynamically probe the characteristics of
> > the FW being loaded. Whichever option you chose, the FW needs to be updated and
> > the former is a lot more simple.
> I don't think I can modify a generic sample, used on other targets to send a
> FW_READY reply.
> How will it be handled on other platforms, if their *_rproc are not
> expecting this kind of message?
>
The only way forward is to come up with a standard specification to describe the
protocol to use, the same way it is done for virtIO for example.
> Thanks,
> Iulia
>
> > Thanks,
> > Mathieu
> >
> > [1]. https://elixir.bootlin.com/linux/latest/source/include/linux/remoteproc.h#L298
> >
> > > Thanks,
> > > Iulia
> > >
> > > > > In these cases, do not wait for a confirmation from the remote processor
> > > > > at start.
> > > > >
> > > > > Added "ignore_dsp_ready" flag while inserting the module to ignore
> > > > > remote processor reply after start.
> > > > > By default, this is off - do not ignore reply from rproc.
> > > > >
> > > > > Signed-off-by: Iuliana Prodan <iuliana.prodan at nxp.com>
> > > > >
> > > > > ---
> > > > > This was discovered while testing openamp_rsc_table sample from Zephyr
> > > > > repo (https://github.com/zephyrproject-rtos/zephyr/tree/main/samples/subsys/ipc/openamp_rsc_table).
> > > > >
> > > > > We have IPC, but the remote proc doesn't send a FW_READY reply.
> > > > > ---
> > > > > drivers/remoteproc/imx_dsp_rproc.c | 15 +++++++++++++++
> > > > > 1 file changed, 15 insertions(+)
> > > > >
> > > > > diff --git a/drivers/remoteproc/imx_dsp_rproc.c b/drivers/remoteproc/imx_dsp_rproc.c
> > > > > index b5634507d953..ed89de2f3b98 100644
> > > > > --- a/drivers/remoteproc/imx_dsp_rproc.c
> > > > > +++ b/drivers/remoteproc/imx_dsp_rproc.c
> > > > > @@ -36,7 +36,13 @@ module_param_named(no_mailboxes, no_mailboxes, int, 0644);
> > > > > MODULE_PARM_DESC(no_mailboxes,
> > > > > "There is no mailbox between cores, so ignore remote proc reply after start, default is 0 (off).");
> > > > > +static unsigned int imx_dsp_rproc_ignore_ready;
> > > > > +module_param_named(ignore_dsp_ready, imx_dsp_rproc_ignore_ready, int, 0644);
> > > > > +MODULE_PARM_DESC(ignore_dsp_ready,
> > > > > + "Ignore remote proc reply after start, default is 0 (off).");
> > > > > +
> > > > > #define REMOTE_IS_READY BIT(0)
> > > > > +#define REMOTE_IGNORE_READY_REPLY BIT(1)
> > > > > #define REMOTE_READY_WAIT_MAX_RETRIES 500
> > > > > /* att flags */
> > > > > @@ -296,6 +302,12 @@ static int imx_dsp_rproc_ready(struct rproc *rproc)
> > > > > if (!priv->rxdb_ch)
> > > > > return 0;
> > > > > + /*
> > > > > + * FW_READY reply is optional/ignored, so don't wait for it.
> > > > > + */
> > > > > + if (priv->flags & REMOTE_IGNORE_READY_REPLY)
> > > > > + return 0;
> > > > > +
> > > > > for (i = 0; i < REMOTE_READY_WAIT_MAX_RETRIES; i++) {
> > > > > if (priv->flags & REMOTE_IS_READY)
> > > > > return 0;
> > > > > @@ -1119,6 +1131,9 @@ static int imx_dsp_rproc_probe(struct platform_device *pdev)
> > > > > else
> > > > > imx_dsp_rproc_mbox_init = imx_dsp_rproc_mbox_alloc;
> > > > > + if (imx_dsp_rproc_ignore_ready)
> > > > > + priv->flags |= REMOTE_IGNORE_READY_REPLY;
> > > > > +
> > > > > dev_set_drvdata(dev, rproc);
> > > > > INIT_WORK(&priv->rproc_work, imx_dsp_rproc_vq_work);
> > > > > --
> > > > > 2.17.1
> > > > >
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