Messages in this thread | | | Subject | Re: [alsa-devel] [RFC PATCH 1/7] soundwire: Add sysfs support for master(s) | From | Pierre-Louis Bossart <> | Date | Mon, 6 May 2019 21:24:17 -0500 |
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>> +int sdw_sysfs_bus_init(struct sdw_bus *bus) >> +{ >> + struct sdw_master_sysfs *master; >> + int err; >> + >> + if (bus->sysfs) { >> + dev_err(bus->dev, "SDW sysfs is already initialized\n"); >> + return -EIO; >> + } >> + >> + master = kzalloc(sizeof(*master), GFP_KERNEL); >> + if (!master) >> + return -ENOMEM; > > Why are you creating a whole new device to put all of this under? Is > this needed? What will the sysfs tree look like when you do this? Why > can't the "bus" device just get all of these attributes and no second > device be created?
I tried a quick hack and indeed we could simplify the code with something as simple as:
[attributes omitted]
static const struct attribute_group sdw_master_node_group = { .attrs = master_node_attrs, .name = "mipi-disco" };
int sdw_sysfs_bus_init(struct sdw_bus *bus) { return sysfs_create_group(&bus->dev->kobj, &sdw_master_node_group); }
void sdw_sysfs_bus_exit(struct sdw_bus *bus) { sysfs_remove_group(&bus->dev->kobj, &sdw_master_node_group); }
which gives me a simpler structure and doesn't require additional pretend-devices:
/sys/bus/acpi/devices/PRP00001:00/int-sdw.0/mipi-disco# ls clock_gears /sys/bus/acpi/devices/PRP00001:00/int-sdw.0/mipi-disco# more clock_gears 8086
The issue I have is that for the _show() functions, I don't see a way to go from the device argument to bus. In the example above I forced the output but would need a helper.
static ssize_t clock_gears_show(struct device *dev, struct device_attribute *attr, char *buf) { struct sdw_bus *bus; // this is what I need to find from dev ssize_t size = 0; int i;
return sprintf(buf, "%d \n", 8086); }
my brain is starting to fry, but I don't see how container_of() would work here since the bus structure contains a pointer to the device. I don't also see a way to check for all devices for the bus_type soundwire. For the slaves we do have a macro based on container_of(), so wondering if we made a mistake in the bus definition? Vinod, any thoughts?
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