Re: [alsa-devel] [PATCH 03/14] soundwire: Add Master registration

On Thu, 19 Oct 2017 05:03:19 +0200, Vinod Koul wrote:

+/**

• • sdw_add_bus_master: add a bus Master instance
• • @bus: bus instance
• • Initializes the bus instance, read properties and create child
• • devices.
• */

+int sdw_add_bus_master(struct sdw_bus *bus) +{

• int ret;
• if (!bus->dev) {

• pr_err("SoundWire bus has no device");
  

• return -ENODEV;
  

• }
• mutex_init(&bus->bus_lock);
• INIT_LIST_HEAD(&bus->slaves);
• /*

• * SDW is an enumerable bus, but devices can be powered off. So,
  

• * they won't be able to report as present.
  

• *
  

• * Create Slave devices based on Slaves described in
  

• * the respective firmware (ACPI/DT)
  

• */
  

• if (IS_ENABLED(CONFIG_ACPI) && bus->dev && ACPI_HANDLE(bus->dev))

• ret = sdw_acpi_find_slaves(bus);
  

• else if (IS_ENABLED(CONFIG_OF) && bus->dev && bus->dev->of_node)

The bus->dev NULL check is already done at the beginning of the function, so here are superfluous.

+static int sdw_delete_slave(struct device *dev, void *data) +{

• struct sdw_slave *slave = dev_to_sdw_dev(dev);
• struct sdw_bus *bus = slave->bus;
• mutex_lock(&bus->bus_lock);
• if (!list_empty(&bus->slaves))

• list_del(&slave->node);
  

You can perform list_del_init() without empty check.

+void sdw_extract_slave_id(struct sdw_bus *bus,

• 	unsigned long long addr, struct sdw_slave_id *id)
  

Use u64 instead.

+{

• dev_dbg(bus->dev, "SDW Slave Addr: %llx", addr);
• /*

• * Spec definition
  

• *   Register		Bit	Contents
  

• *   DevId_0 [7:4]	47:44	sdw_version
  

• *   DevId_0 [3:0]	43:40	unique_id
  

• *   DevId_1		39:32	mfg_id [15:8]
  

• *   DevId_2		31:24	mfg_id [7:0]
  

• *   DevId_3		23:16	part_id [15:8]
  

• *   DevId_4		15:08	part_id [7:0]
  

• *   DevId_5		07:00	class_id
  

• */
  

• id->sdw_version = (addr >> 44) & GENMASK(3, 0);
• id->unique_id = (addr >> 40) & GENMASK(3, 0);
• id->mfg_id = (addr >> 24) & GENMASK(15, 0);
• id->part_id = (addr >> 8) & GENMASK(15, 0);
• id->class_id = addr & GENMASK(7, 0);
• dev_info(bus->dev,

• "SDW Slave class_id %x, part_id %x, mfg_id %x, unique_id %x, version %x",
  

• 		id->class_id, id->part_id, id->mfg_id,
  

• 		id->unique_id, id->sdw_version);
  

Do we want to print a message always at each invocation?

+static int sdw_slave_add(struct sdw_bus *bus,

• struct sdw_slave_id *id, struct fwnode_handle *fwnode)
  

+{

• struct sdw_slave *slave;
• char name[32];
• int ret;
• slave = kzalloc(sizeof(*slave), GFP_KERNEL);
• if (!slave)

• return -ENOMEM;
  

• /* Initialize data structure */
• memcpy(&slave->id, id, sizeof(*id));
• /* name shall be sdw:link:mfg:part:class:unique */
• snprintf(name, sizeof(name), "sdw:%x:%x:%x:%x:%x",

• 	bus->link_id, id->mfg_id, id->part_id,
  

• 	id->class_id, id->unique_id);
  

You can set the name directly via dev_set_name(). It's printf format, after all.

• slave->dev.parent = bus->dev;
• slave->dev.fwnode = fwnode;
• dev_set_name(&slave->dev, "%s", name);
• slave->dev.release = sdw_slave_release;
• slave->dev.bus = &sdw_bus_type;
• slave->bus = bus;
• slave->status = SDW_SLAVE_UNATTACHED;
• slave->dev_num = 0;
• mutex_lock(&bus->bus_lock);
• list_add_tail(&slave->node, &bus->slaves);
• mutex_unlock(&bus->bus_lock);
• ret = device_register(&slave->dev);
• if (ret) {

• dev_err(bus->dev, "Failed to add slave: ret %d\n", ret);
  

• /*
  

•  * On err, don't free but drop ref as this will be freed
  

•  * when release method is invoked.
  

•  */
  

• put_device(&slave->dev);
  

Wouldn't it leave a stale link to bus?

thanks,

Takashi