On Wed 14 Oct 08:09 PDT 2015, yfw wrote:
> Hi Bjorn,
>
> On 2015/10/10 4:48, Bjorn Andersson wrote:
> > With the qcom_smd_open_channel() API we allow SMD devices to open
> > additional SMD channels, to allow implementation of multi-channel SMD
> > devices - like Bluetooth.
> >
> > Channels are opened from the same edge as the calling SMD device is tied
> > to.
> >
[..]
> > +/**
> > + * qcom_smd_open_channel() - claim additional channels on the same edge
> > + * @sdev: smd_device handle
> > + * @name: channel name
> > + * @cb: callback method to use for incoming data
> > + *
> > + * Returns a channel handle on success, or -EPROBE_DEFER if the channel
> > isn't
> > + * ready.
> > + */
> > +struct qcom_smd_channel *qcom_smd_open_channel(struct qcom_smd_device
> > *sdev,
> > + const char *name,
> > + qcom_smd_cb_t cb)
> > +{
> > + struct qcom_smd_channel *channel;
> > + struct qcom_smd_edge *edge = sdev->channel->edge;
> > + int ret;
> > +
> > + /* Wait up to HZ for the channel to appear */
> > + ret = wait_event_interruptible_timeout(edge->new_channel_event,
> > + (channel = qcom_smd_find_channel(edge, name)) != NULL,
> > + HZ);
> > + if (!ret)
> > + return ERR_PTR(-ETIMEDOUT);
> > +
> > + if (channel->state != SMD_CHANNEL_CLOSED) {
> > + dev_err(&sdev->dev, "channel %s is busy\n", channel->name);
> > + return ERR_PTR(-EBUSY);
> > + }
> > +
> > + channel->qsdev = sdev;
> > + ret = qcom_smd_channel_open(channel, cb);
> > + if (ret) {
> > + channel->qsdev = NULL;
> > + return ERR_PTR(ret);
> > + }
> > +
> > + /*
> > + * Append the list of channel to the channels associated with the sdev
> > + */
> > + list_add_tail(&channel->dev_list, &sdev->channel->dev_list);
> > +
> > + return channel;
> > +}
> > +EXPORT_SYMBOL(qcom_smd_open_channel);
> > +
> Do we need qcom_smd_close_channel API here?
>
On success the channel is associated with the qcom_smd_device, which
tears down all associated channels on destruction.
I have not yet seen any reason for decoupling the life cycle of a
channel further from the device (in most cases it's very must 1:1).
But I will update the comment above to clarify this fact, thanks!
Regards,
Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
