Re: [PATCH v5 1/2] rpmsg: core: add API to get message length

[Arnaud Pouliquen <arnaud.pouliquen@xxxxxx>]

Hi Suman

On 9/3/19 6:06 PM, Suman Anna wrote:
> Hi Arnaud,
>
> On 9/3/19 4:49 AM, Arnaud Pouliquen wrote:
> > hi Suman
> >
> > On 8/29/19 12:34 AM, Suman Anna wrote:
> > > Hi Arnaud,
> > >
> > > On 8/28/19 10:19 AM, Arnaud Pouliquen wrote:
> > > > Return the rpmsg buffer size for sending message, so rpmsg users
> > > > can split a long message in several sub rpmsg buffers.
> > >
> > > Thanks for the patch, I also have a need for the same to be able to
> > > compute permissible payload size. Minor comments below.
> >
> > Thanks for your review. i will update it ASAP. Then if you need it and
> > ack it, i suppose that we could request Bjorn to integrate it in a first
> > step, if the rpmsg tty driver has not a level of quality sufficient to
> > be accepted...
>
> Yeah, this patch can always be merged independently ahead of the rpmsg
> tty driver. Anyways, the tty patch will have to be picked up by a
> separate maintainer right. So, it would be nice to get the revised
> version get into 5.4

Sure, I plan to send a new version of the series today.
I would prefer not to split the series, just to simplify the review and 
the tests. if this patch is cherry-picked and integrated independently 
by Bjorn, I will simply sent a new version of the rpmsg tty driver 
without it.

Regards
Arnaud

> regards
> Suman
>
> > Regards
> > Arnaud
> > > > Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxx>
> > > > ---
> > > > V4 to V5 :
> > > >     - rename rpmsg_get_buf_payload_size to rpmsg_get_mtu
> > > >
> > > >    drivers/rpmsg/rpmsg_core.c       | 21 +++++++++++++++++++++
> > > >    drivers/rpmsg/rpmsg_internal.h   |  2 ++
> > > >    drivers/rpmsg/virtio_rpmsg_bus.c | 10 ++++++++++
> > > >    include/linux/rpmsg.h            | 10 ++++++++++
> > > >    4 files changed, 43 insertions(+)
> > > >
> > > > diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> > > > index 8122807db380..daca2e24fc71 100644
> > > > --- a/drivers/rpmsg/rpmsg_core.c
> > > > +++ b/drivers/rpmsg/rpmsg_core.c
> > > > @@ -283,6 +283,27 @@ int rpmsg_trysend_offchannel(struct
> > > > rpmsg_endpoint *ept, u32 src, u32 dst,
> > > >    }
> > > >    EXPORT_SYMBOL(rpmsg_trysend_offchannel);
> > > >    +/**
> > > > + * rpmsg_get_mtu() - get maximum transmission buffer size for
> > > > sending message.
> > > > + * @ept: the rpmsg endpoint
> > > > + *
> > > > + * This function returns maximum buffer size available for a single
> > > > message.
> > > > + *
> > > > + * Return: the maximum transmission size on success and an
> > > > appropriate error
> > > > + * value on failure.
> > > > + */
> > > > +
> > > > +ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
> > > > +{
> > > > +    if (WARN_ON(!ept))
> > > > +        return -EINVAL;
> > > > +    if (!ept->ops->get_buf_mtu)
> > >
> > > How about calling the ops just get_mtu or rename the function to follow
> > > the ops name, like all the others.
> > >
> > > > +        return -ENXIO;
> > >
> > > Perhaps ENOTSUPP or EOPNOTSUPP.
> > >
> > > > +
> > > > +    return ept->ops->get_buf_mtu(ept);
> > > > +}
> > > > +EXPORT_SYMBOL(rpmsg_get_mtu);
> > > > +
> > > >    /*
> > > >     * match an rpmsg channel with a channel info struct.
> > > >     * this is used to make sure we're not creating rpmsg devices for
> > > > channels
> > > > diff --git a/drivers/rpmsg/rpmsg_internal.h
> > > > b/drivers/rpmsg/rpmsg_internal.h
> > > > index 0d791c30b7ea..645c402569ac 100644
> > > > --- a/drivers/rpmsg/rpmsg_internal.h
> > > > +++ b/drivers/rpmsg/rpmsg_internal.h
> > > > @@ -46,6 +46,7 @@ struct rpmsg_device_ops {
> > > >     * @trysend:        see @rpmsg_trysend(), required
> > > >     * @trysendto:        see @rpmsg_trysendto(), optional
> > > >     * @trysend_offchannel:    see @rpmsg_trysend_offchannel(), optional
> > > > + * @get_buf_payload_size: see @rpmsg_get_buf_payload_size(), optional
> > >
> > > Missed updating the kerneldoc to the new name.
> > >
> > > >     *
> > > >     * Indirection table for the operations that a rpmsg backend should
> > > > implement.
> > > >     * In addition to @destroy_ept, the backend must at least implement
> > > > @send and
> > > > @@ -65,6 +66,7 @@ struct rpmsg_endpoint_ops {
> > > >                     void *data, int len);
> > > >        __poll_t (*poll)(struct rpmsg_endpoint *ept, struct file *filp,
> > > >                     poll_table *wait);
> > > > +    ssize_t (*get_buf_mtu)(struct rpmsg_endpoint *ept);
> > > >    };
> > > >      int rpmsg_register_device(struct rpmsg_device *rpdev);
> > > > diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c
> > > > b/drivers/rpmsg/virtio_rpmsg_bus.c
> > > > index e757f0038a1c..f80b1ad23e7e 100644
> > > > --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> > > > +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> > > > @@ -178,6 +178,7 @@ static int virtio_rpmsg_trysendto(struct
> > > > rpmsg_endpoint *ept, void *data,
> > > >                      int len, u32 dst);
> > > >    static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint
> > > > *ept, u32 src,
> > > >                           u32 dst, void *data, int len);
> > > > +static ssize_t virtio_get_buf_mtu(struct rpmsg_endpoint *ept);
> > >
> > > Minor nit, virtio_rpmsg_ prefix similar to all the other ops.
> > >
> > > regards
> > > Suman
> > >
> > > >      static const struct rpmsg_endpoint_ops virtio_endpoint_ops = {
> > > >        .destroy_ept = virtio_rpmsg_destroy_ept,
> > > > @@ -187,6 +188,7 @@ static const struct rpmsg_endpoint_ops
> > > > virtio_endpoint_ops = {
> > > >        .trysend = virtio_rpmsg_trysend,
> > > >        .trysendto = virtio_rpmsg_trysendto,
> > > >        .trysend_offchannel = virtio_rpmsg_trysend_offchannel,
> > > > +    .get_buf_mtu = virtio_get_buf_mtu,
> > > >    };
> > > >      /**
> > > > @@ -702,6 +704,14 @@ static int
> > > > virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src,
> > > >        return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len,
> > > > false);
> > > >    }
> > > >    +static ssize_t virtio_get_buf_mtu(struct rpmsg_endpoint *ept)
> > > > +{
> > > > +    struct rpmsg_device *rpdev = ept->rpdev;
> > > > +    struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
> > > > +
> > > > +    return vch->vrp->buf_size - sizeof(struct rpmsg_hdr);
> > > > +}
> > > > +
> > > >    static int rpmsg_recv_single(struct virtproc_info *vrp, struct
> > > > device *dev,
> > > >                     struct rpmsg_hdr *msg, unsigned int len)
> > > >    {
> > > > diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> > > > index 9fe156d1c018..9d638bf2bdce 100644
> > > > --- a/include/linux/rpmsg.h
> > > > +++ b/include/linux/rpmsg.h
> > > > @@ -135,6 +135,8 @@ int rpmsg_trysend_offchannel(struct
> > > > rpmsg_endpoint *ept, u32 src, u32 dst,
> > > >    __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
> > > >                poll_table *wait);
> > > >    +ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
> > > > +
> > > >    #else
> > > >      static inline int register_rpmsg_device(struct rpmsg_device *dev)
> > > > @@ -242,6 +244,14 @@ static inline __poll_t rpmsg_poll(struct
> > > > rpmsg_endpoint *ept,
> > > >        return 0;
> > > >    }
> > > >    +static ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
> > > > +{
> > > > +    /* 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 */