On Tue, Jun 26, 2018 at 01:57:21PM -0700, Evan Green wrote: > Hi Georgi. Thanks for the new spin of this. > > On Wed, Jun 20, 2018 at 5:11 AM Georgi Djakov <georgi.djakov@xxxxxxxxxx> wrote: > > > > This patch introduce a new API to get requirements and configure the > > interconnect buses across the entire chipset to fit with the current > > demand. > > > > The API is using a consumer/provider-based model, where the providers are > > the interconnect buses and the consumers could be various drivers. > > The consumers request interconnect resources (path) between endpoints and > > set the desired constraints on this data flow path. The providers receive > > requests from consumers and aggregate these requests for all master-slave > > pairs on that path. Then the providers configure each participating in the > > topology node according to the requested data flow path, physical links and > > constraints. The topology could be complicated and multi-tiered and is SoC > > specific. > > > > Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxx> > > --- > > Documentation/interconnect/interconnect.rst | 96 ++++ > > drivers/Kconfig | 2 + > > drivers/Makefile | 1 + > > drivers/interconnect/Kconfig | 10 + > > drivers/interconnect/Makefile | 2 + > > drivers/interconnect/core.c | 586 ++++++++++++++++++++ > > include/linux/interconnect-provider.h | 127 +++++ > > include/linux/interconnect.h | 42 ++ > > 8 files changed, 866 insertions(+) > > create mode 100644 Documentation/interconnect/interconnect.rst > > create mode 100644 drivers/interconnect/Kconfig > > create mode 100644 drivers/interconnect/Makefile > > create mode 100644 drivers/interconnect/core.c > > create mode 100644 include/linux/interconnect-provider.h > > create mode 100644 include/linux/interconnect.h > > > > ... > > > > diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c > > new file mode 100644 > > index 000000000000..e7f96fc6722e > > --- /dev/null > > +++ b/drivers/interconnect/core.c > > @@ -0,0 +1,586 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Interconnect framework core driver > > + * > > + * Copyright (c) 2018, Linaro Ltd. > > + * Author: Georgi Djakov <georgi.djakov@xxxxxxxxxx> > > + */ > > + > > +#include <linux/device.h> > > +#include <linux/idr.h> > > +#include <linux/init.h> > > +#include <linux/interconnect.h> > > +#include <linux/interconnect-provider.h> > > +#include <linux/list.h> > > +#include <linux/module.h> > > +#include <linux/mutex.h> > > +#include <linux/slab.h> > > + > > +static DEFINE_IDR(icc_idr); > > +static LIST_HEAD(icc_provider_list); > > +static DEFINE_MUTEX(icc_lock); > > + > > +/** > > + * struct icc_req - constraints that are attached to each node > > + * > > + * @req_node: entry in list of requests for the particular @node > > + * @node: the interconnect node to which this constraint applies > > + * @dev: reference to the device that sets the constraints > > + * @avg_bw: an integer describing the average bandwidth in kbps > > + * @peak_bw: an integer describing the peak bandwidth in kbps > > + */ > > +struct icc_req { > > + struct hlist_node req_node; > > + struct icc_node *node; > > + struct device *dev; > > + u32 avg_bw; > > + u32 peak_bw; > > +}; > > + > > +/** > > + * struct icc_path - interconnect path structure > > + * @num_nodes: number of hops (nodes) > > + * @reqs: array of the requests applicable to this path of nodes > > + */ > > +struct icc_path { > > + size_t num_nodes; > > + struct icc_req reqs[0]; > > +}; > > + > > +static struct icc_node *node_find(const int id) > > +{ > > + struct icc_node *node; > > + > > + mutex_lock(&icc_lock); > > + node = idr_find(&icc_idr, id); > > + mutex_unlock(&icc_lock); > > I wonder if this is too low of a level to be dealing with the lock. I > notice that everywhere you use this function, you afterwards > immediately grab the lock and do more stuff. Maybe this function > should have a comment saying it assumes the lock is already held, and > then you can grab the lock in the callers, since you're doing that > anyway. I think the canonical way to document the expectation would be: WARN_ON(!mutex_is_locked(&icc_lock)); > > + > > + return node; > > +} > > + > > +static struct icc_path *path_allocate(struct icc_node *dst, ssize_t num_nodes) > > +{ > > + struct icc_node *node = dst; > > + struct icc_path *path; > > + size_t i; > > + > > + path = kzalloc(sizeof(*path) + num_nodes * sizeof(*path->reqs), > > + GFP_KERNEL); > > + if (!path) > > + return ERR_PTR(-ENOMEM); > > + > > + path->num_nodes = num_nodes; > > + > > + for (i = 0; i < num_nodes; i++) { > > + hlist_add_head(&path->reqs[i].req_node, &node->req_list); > > + > > + path->reqs[i].node = node; > > + /* reference to previous node was saved during path traversal */ > > + node = node->reverse; > > + } > > + > > + return path; > > +} > > + > > +static struct icc_path *path_find(struct device *dev, struct icc_node *src, > > + struct icc_node *dst) > > +{ > > I personally prefer a comment somewhere indicating that this function > assumes icc_lock is already held. Not sure if that's conventional or > not. Same as above. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html