On Thu, 23 Jun 2022 19:48:07 -0700
Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> Recall that the primary role of the cxl_mem driver is to probe if the
> given endoint is connected to a CXL port topology. In that process it
> walks its device ancestry to its PCI root port. If that root port is
> also a CXL root port then the probe process adds cxl_port object
> instances at switch in the path between to the root and the endpoint. As
> those cxl_port instances are added, or if a previous enumeration
> attempt already created the port a 'struct cxl_ep' instance is
port, a
would make this more readable.
> registered with that port to track the endpoints interested in that
> port.
>
> At the time the cxl_ep is registered the downstream egress path from the
> port to the endpoint is known. Take the opportunity to record that
> information as it will be needed for dynamic programming of decoder
> targets during region provisioning.
>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Otherwise, one comment on function naming not reflecting what it does
inline.
Jonathan
> ---
> drivers/cxl/core/port.c | 52 ++++++++++++++++++++++++++++++++---------------
> drivers/cxl/cxl.h | 2 ++
> 2 files changed, 37 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 4e4e26ca507c..c54e1dbf92cb 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -866,8 +866,9 @@ static struct cxl_ep *find_ep(struct cxl_port *port, struct device *ep_dev)
> return NULL;
> }
>
> -static int add_ep(struct cxl_port *port, struct cxl_ep *new)
> +static int add_ep(struct cxl_ep *new)
> {
> + struct cxl_port *port = new->dport->port;
> struct cxl_ep *dup;
>
> device_lock(&port->dev);
> @@ -885,14 +886,14 @@ static int add_ep(struct cxl_port *port, struct cxl_ep *new)
>
> /**
> * cxl_add_ep - register an endpoint's interest in a port
> - * @port: a port in the endpoint's topology ancestry
> + * @dport: the dport that routes to @ep_dev
> * @ep_dev: device representing the endpoint
> *
> * Intermediate CXL ports are scanned based on the arrival of endpoints.
> * When those endpoints depart the port can be destroyed once all
> * endpoints that care about that port have been removed.
> */
> -static int cxl_add_ep(struct cxl_port *port, struct device *ep_dev)
> +static int cxl_add_ep(struct cxl_dport *dport, struct device *ep_dev)
> {
> struct cxl_ep *ep;
> int rc;
> @@ -903,8 +904,9 @@ static int cxl_add_ep(struct cxl_port *port, struct device *ep_dev)
>
> INIT_LIST_HEAD(&ep->list);
> ep->ep = get_device(ep_dev);
> + ep->dport = dport;
>
> - rc = add_ep(port, ep);
> + rc = add_ep(ep);
> if (rc)
> cxl_ep_release(ep);
> return rc;
> @@ -913,11 +915,13 @@ static int cxl_add_ep(struct cxl_port *port, struct device *ep_dev)
> struct cxl_find_port_ctx {
> const struct device *dport_dev;
> const struct cxl_port *parent_port;
> + struct cxl_dport **dport;
> };
>
> static int match_port_by_dport(struct device *dev, const void *data)
> {
This seems a little oddly name for a function that 'returns'
the dport via ctx when a match is found.
> const struct cxl_find_port_ctx *ctx = data;
> + struct cxl_dport *dport;
> struct cxl_port *port;
>
> if (!is_cxl_port(dev))
> @@ -926,7 +930,10 @@ static int match_port_by_dport(struct device *dev, const void *data)
> return 0;
>
> port = to_cxl_port(dev);
> - return cxl_find_dport_by_dev(port, ctx->dport_dev) != NULL;
> + dport = cxl_find_dport_by_dev(port, ctx->dport_dev);
> + if (ctx->dport)
> + *ctx->dport = dport;
> + return dport != NULL;
> }
>
> static struct cxl_port *__find_cxl_port(struct cxl_find_port_ctx *ctx)
> @@ -942,24 +949,32 @@ static struct cxl_port *__find_cxl_port(struct cxl_find_port_ctx *ctx)
> return NULL;
> }
>
> -static struct cxl_port *find_cxl_port(struct device *dport_dev)
> +static struct cxl_port *find_cxl_port(struct device *dport_dev,
> + struct cxl_dport **dport)
> {
> struct cxl_find_port_ctx ctx = {
> .dport_dev = dport_dev,
> + .dport = dport,
> };
> + struct cxl_port *port;
>
> - return __find_cxl_port(&ctx);
> + port = __find_cxl_port(&ctx);
> + return port;
> }
>
> static struct cxl_port *find_cxl_port_at(struct cxl_port *parent_port,
> - struct device *dport_dev)
> + struct device *dport_dev,
> + struct cxl_dport **dport)
> {
> struct cxl_find_port_ctx ctx = {
> .dport_dev = dport_dev,
> .parent_port = parent_port,
> + .dport = dport,
> };
> + struct cxl_port *port;
>
> - return __find_cxl_port(&ctx);
> + port = __find_cxl_port(&ctx);
> + return port;
> }
>
> /*
> @@ -1044,7 +1059,7 @@ static void cxl_detach_ep(void *data)
> if (!dport_dev)
> break;
>
> - port = find_cxl_port(dport_dev);
> + port = find_cxl_port(dport_dev, NULL);
> if (!port)
> continue;
>
> @@ -1119,6 +1134,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
> struct device *dparent = grandparent(dport_dev);
> struct cxl_port *port, *parent_port = NULL;
> resource_size_t component_reg_phys;
> + struct cxl_dport *dport;
> int rc;
>
> if (!dparent) {
> @@ -1132,7 +1148,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
> return -ENXIO;
> }
>
> - parent_port = find_cxl_port(dparent);
> + parent_port = find_cxl_port(dparent, NULL);
> if (!parent_port) {
> /* iterate to create this parent_port */
> return -EAGAIN;
> @@ -1147,13 +1163,14 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
> goto out;
> }
>
> - port = find_cxl_port_at(parent_port, dport_dev);
> + port = find_cxl_port_at(parent_port, dport_dev, &dport);
> if (!port) {
> component_reg_phys = find_component_registers(uport_dev);
> port = devm_cxl_add_port(&parent_port->dev, uport_dev,
> component_reg_phys, parent_port);
> + /* retry find to pick up the new dport information */
> if (!IS_ERR(port))
> - get_device(&port->dev);
> + port = find_cxl_port_at(parent_port, dport_dev, &dport);
> }
> out:
> device_unlock(&parent_port->dev);
> @@ -1163,7 +1180,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
> else {
> dev_dbg(&cxlmd->dev, "add to new port %s:%s\n",
> dev_name(&port->dev), dev_name(port->uport));
> - rc = cxl_add_ep(port, &cxlmd->dev);
> + rc = cxl_add_ep(dport, &cxlmd->dev);
> if (rc == -EEXIST) {
> /*
> * "can't" happen, but this error code means
> @@ -1197,6 +1214,7 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
> for (iter = dev; iter; iter = grandparent(iter)) {
> struct device *dport_dev = grandparent(iter);
> struct device *uport_dev;
> + struct cxl_dport *dport;
> struct cxl_port *port;
>
> if (!dport_dev)
> @@ -1212,12 +1230,12 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
> dev_dbg(dev, "scan: iter: %s dport_dev: %s parent: %s\n",
> dev_name(iter), dev_name(dport_dev),
> dev_name(uport_dev));
> - port = find_cxl_port(dport_dev);
> + port = find_cxl_port(dport_dev, &dport);
> if (port) {
> dev_dbg(&cxlmd->dev,
> "found already registered port %s:%s\n",
> dev_name(&port->dev), dev_name(port->uport));
> - rc = cxl_add_ep(port, &cxlmd->dev);
> + rc = cxl_add_ep(dport, &cxlmd->dev);
>
> /*
> * If the endpoint already exists in the port's list,
> @@ -1258,7 +1276,7 @@ EXPORT_SYMBOL_NS_GPL(devm_cxl_enumerate_ports, CXL);
>
> struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd)
> {
> - return find_cxl_port(grandparent(&cxlmd->dev));
> + return find_cxl_port(grandparent(&cxlmd->dev), NULL);
> }
> EXPORT_SYMBOL_NS_GPL(cxl_mem_find_port, CXL);
>
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index d8edbdaa6208..e654251a54dd 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -363,10 +363,12 @@ struct cxl_dport {
> /**
> * struct cxl_ep - track an endpoint's interest in a port
> * @ep: device that hosts a generic CXL endpoint (expander or accelerator)
> + * @dport: which dport routes to this endpoint on this port
> * @list: node on port->endpoints list
> */
> struct cxl_ep {
> struct device *ep;
> + struct cxl_dport *dport;
> struct list_head list;
> };
>
>
