On Tuesday 19 August 2014, German Rivera wrote: > >> + * @dev_node: Node in the container's child list > > > > Same here: just use the device model's list management instead if you can, > > or explain why this is needed. > > > We still need to keep a per-bus list of child devices (devices contained > in a given DPRC object). Unless I'm missing something, > I think the device model's list management links together all the > devices of the same bus type. We are trying to follow a similar approach > to the pci_dev/pci_bus structs.
There are multiple lists in the device handling. device_for_each_child() should iterate over the children of a particular device using the klist_children member. > >> +/** > >> + * struct fsl_mc_dprc - Data Path Resource Container (DPRC) object > >> + * @magic: marker to verify identity of this structure > >> + * @mc_dev: pointer to MC object device object for this DPRC > >> + * @mutex: mutex to serialize access to the container. > >> + * @child_device_count: have the count of devices in this DPRC > >> + * @child_list: anchor node of list of child devices on this DPRC > >> + */ > >> +struct fsl_mc_dprc { > >> +# define FSL_MC_DPRC_MAGIC FSL_MC_MAGIC('D', 'P', 'R', 'C') > >> + uint32_t magic; > >> + struct fsl_mc_device *mc_dev; > >> + struct mutex mutex; /* serializes access to fields below */ > >> + uint16_t child_device_count; /* Count of devices in this DPRC */ > >> + struct list_head child_list; > >> +}; > > > > It's not clear what this represents to me. mc_dev presumably already > > has a list of children, so why not just use a pointer to mc_dev > > and remove this structure entirely? > > > This structure represents the per-bus (per DPRC object) information. > It is kind of the equivalent to 'struct pci_bus' in the PCI world. > I have renamed this struct to 'struct fsl_mc_bus'. Ok, I'll look at the new version when I get back to Germany. I still think that can remove all members of the current structure and just use the same structure for fsl_mc_bus and fsl_mc_device. If you really need a small number of extra members beyond what is in the device, you have two other choices: a) put the members into the device structure as well but not use them for a device that is not a bus b) embed the device structure within the bus structure like struct fsl_mc_bus { int something; struct fsl_mc_device; }; and then use container_of() to go from the device to the bus where needed rather than having two objects that are allocated separately. This is what a lot of other subsystems (not PCI) do. See for instance platform_device, which often has child devices as well. Arnd -- 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/