Re: [PATCH V4 1/3] rpmsg: core: Add signal API support

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Tue, 29 Nov 2022 at 02:29, Arnaud POULIQUEN
<arnaud.pouliquen@foss.st.com> wrote:
>
> Hi Sarannya,
>
> On 11/28/22 19:02, Sarannya S wrote:
> > Some transports like Glink support the state notifications between
> > clients using flow control signals similar to serial protocol signals.
> > Local glink client drivers can send and receive flow control status
> > to glink clients running on remote processors.
> >
> > Add APIs to support sending and receiving of flow control status by
> > rpmsg clients.
> >
> > Signed-off-by: Deepak Kumar Singh <quic_deesin@quicinc.com>
> > Signed-off-by: Sarannya S <quic_sarannya@quicinc.com>
> > ---
> >  drivers/rpmsg/rpmsg_core.c     | 20 ++++++++++++++++++++
> >  drivers/rpmsg/rpmsg_internal.h |  2 ++
> >  include/linux/rpmsg.h          | 15 +++++++++++++++
> >  3 files changed, 37 insertions(+)
> >
> > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> > index d6dde00e..0c5bf67 100644
> > --- a/drivers/rpmsg/rpmsg_core.c
> > +++ b/drivers/rpmsg/rpmsg_core.c
> > @@ -331,6 +331,24 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> >  EXPORT_SYMBOL(rpmsg_trysend_offchannel);
> >
> >  /**
> > + * rpmsg_set_flow_control() - sets/clears serial flow control signals
> > + * @ept:     the rpmsg endpoint
> > + * @enable:  enable or disable serial flow control
> > + *
> > + * Return: 0 on success and an appropriate error value on failure.
> > + */
> > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable)
>
> Seems that you did not take into account comment in your V3 asking you to
> add the destination address of the endpoint as parameter

I will not review this patchset until Arnaud's comment is addressed or
a reason for the omission is provided.

>
> Regards,
> Arnaud
>
> > +{
> > +     if (WARN_ON(!ept))
> > +             return -EINVAL;
> > +     if (!ept->ops->set_flow_control)
> > +             return -ENXIO;
> > +
> > +     return ept->ops->set_flow_control(ept, enable);
> > +}
> > +EXPORT_SYMBOL(rpmsg_set_flow_control);
> > +
> > +/**
> >   * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
> >   * @ept: the rpmsg endpoint
> >   *
> > @@ -539,6 +557,8 @@ static int rpmsg_dev_probe(struct device *dev)
> >
> >               rpdev->ept = ept;
> >               rpdev->src = ept->addr;
> > +
> > +             ept->flow_cb = rpdrv->flowcontrol;
> >       }
> >
> >       err = rpdrv->probe(rpdev);
> > diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> > index 39b646d..4fea45a 100644
> > --- a/drivers/rpmsg/rpmsg_internal.h
> > +++ b/drivers/rpmsg/rpmsg_internal.h
> > @@ -55,6 +55,7 @@ struct rpmsg_device_ops {
> >   * @trysendto:               see @rpmsg_trysendto(), optional
> >   * @trysend_offchannel:      see @rpmsg_trysend_offchannel(), optional
> >   * @poll:            see @rpmsg_poll(), optional
> > + * @set_flow_control:        see @rpmsg_set_flow_control(), optional
> >   * @get_mtu:         see @rpmsg_get_mtu(), optional
> >   *
> >   * Indirection table for the operations that a rpmsg backend should implement.
> > @@ -75,6 +76,7 @@ struct rpmsg_endpoint_ops {
> >                            void *data, int len);
> >       __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
> >                            poll_table *wait);
> > +     int (*set_flow_control)(struct rpmsg_endpoint *ept, bool enable);
> >       ssize_t (*get_mtu)(struct rpmsg_endpoint *ept);
> >  };
> >
> > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> > index 523c98b..cc7a917 100644
> > --- a/include/linux/rpmsg.h
> > +++ b/include/linux/rpmsg.h
> > @@ -64,12 +64,14 @@ struct rpmsg_device {
> >  };
> >
> >  typedef int (*rpmsg_rx_cb_t)(struct rpmsg_device *, void *, int, void *, u32);
> > +typedef int (*rpmsg_flowcontrol_cb_t)(struct rpmsg_device *, void *, bool);
> >
> >  /**
> >   * struct rpmsg_endpoint - binds a local rpmsg address to its user
> >   * @rpdev: rpmsg channel device
> >   * @refcount: when this drops to zero, the ept is deallocated
> >   * @cb: rx callback handler
> > + * @flow_cb: remote flow control callback handler
> >   * @cb_lock: must be taken before accessing/changing @cb
> >   * @addr: local rpmsg address
> >   * @priv: private data for the driver's use
> > @@ -92,6 +94,7 @@ struct rpmsg_endpoint {
> >       struct rpmsg_device *rpdev;
> >       struct kref refcount;
> >       rpmsg_rx_cb_t cb;
> > +     rpmsg_flowcontrol_cb_t flow_cb;
> >       struct mutex cb_lock;
> >       u32 addr;
> >       void *priv;
> > @@ -106,6 +109,7 @@ struct rpmsg_endpoint {
> >   * @probe: invoked when a matching rpmsg channel (i.e. device) is found
> >   * @remove: invoked when the rpmsg channel is removed
> >   * @callback: invoked when an inbound message is received on the channel
> > + * @flowcontrol: invoked when remote side flow control status is received
> >   */
> >  struct rpmsg_driver {
> >       struct device_driver drv;
> > @@ -113,6 +117,7 @@ struct rpmsg_driver {
> >       int (*probe)(struct rpmsg_device *dev);
> >       void (*remove)(struct rpmsg_device *dev);
> >       int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
> > +     int (*flowcontrol)(struct rpmsg_device *, void *, bool);
> >  };
> >
> >  static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
> > @@ -192,6 +197,8 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
> >
> >  ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
> >
> > +int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable);
> > +
> >  #else
> >
> >  static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> > @@ -316,6 +323,14 @@ static inline ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
> >       return -ENXIO;
> >  }
> >
> > +static inline int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool enable)
> > +{
> > +     /* This shouldn't be possible */
> > +     WARN_ON(1);
> > +
> > +     return -ENXIO;
> > +}
> > +
> >  #endif /* IS_ENABLED(CONFIG_RPMSG) */
> >
> >  /* use a macro to avoid include chaining to get THIS_MODULE */