sjur.brandeland@xxxxxxxxxxxxxx writes:
> From: Vikram ARV <vikram.arv@xxxxxxxxxxxxxx>
>
> Add the the Virtio shared memory driver for STE Modems.
> caif_virtio is implemented utilizing the virtio framework
> for data transport and is managed with the remoteproc frameworks.
>
> The Virtio queue is used for transmitting data to the modem, and
> the new vringh implementation is receiving data over the vring.
OK, let's refine vringh now we can see another user:
> + * @head: Last descriptor ID we received from vringh_getdesc_kern.
> + * We use this to put descriptor back on the used ring. USHRT_MAX is
> + * used to indicate invalid head-id.
> + */
> +struct cfv_napi_context {
> + struct vringh_kiov riov;
> + unsigned short head;
> +};
Usually we use an int, and -1. I imagine it'll take no more space,
due to padding.
> +static inline void ctx_prep_iov(struct cfv_napi_context *ctx)
> +{
> + if (ctx->riov.allocated) {
> + kfree(ctx->riov.iov);
> + ctx->riov.iov = NULL;
> + ctx->riov.allocated = false;
> + }
> + ctx->riov.iov = NULL;
> + ctx->riov.i = 0;
> + ctx->riov.max = 0;
> +}
Hmm, we should probably make sure you don't have to do this: that if
allocated once, you can simply reuse it by setting i = 0.
(This requires some care in the error handling paths, so we don't
free it from under you)...
And you probably want to free this up in cfv_remove() instead?
I'll create and test a patch now.
> + if (riov->i == riov->max) {
> + if (cfv->ctx.head != USHRT_MAX) {
> + vringh_complete_kern(cfv->vr_rx,
> + cfv->ctx.head,
> + 0);
> + cfv->ctx.head = USHRT_MAX;
> + }
> +
> + ctx_prep_iov(&cfv->ctx);
> + err = vringh_getdesc_kern(
> + cfv->vr_rx,
> + riov,
> + &wiov,
> + &cfv->ctx.head,
> + GFP_ATOMIC);
> +
> + if (err <= 0)
> + goto out;
> +
> + if (wiov.max != 0) {
> + /* CAIF does not use write descriptors */
> + err = -EPROTO;
> + goto out;
> + }
This is probably a common case, so we should generate this error inside
vringh_getdesc (if wiov is NULL).
I'll do that too...
> +module_driver(caif_virtio_driver, register_virtio_driver,
> + unregister_virtio_driver);
> +MODULE_DEVICE_TABLE(virtio, id_table);
The comment on module_driver says:
* Use this macro to construct bus specific macros for registering
* drivers, and do not use it on its own.
Want to send me a patch to define module_virtio_driver?
Thanks!
Rusty.
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