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

[Arnaud Pouliquen <arnaud.pouliquen@st.com>]

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@st.com>
>>>> ---
>>>> 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 */
>>>>
>>>
>