>From: Jakub Kicinski <kuba@xxxxxxxxxx>
>Sent: Tuesday, June 13, 2023 1:45 AM
>
>On Fri, 9 Jun 2023 14:18:46 +0200 Arkadiusz Kubalewski wrote:
>> + xa_for_each(xa_pins, i, ref) {
>> + if (ref->pin != pin)
>> + continue;
>> + reg = dpll_pin_registration_find(ref, ops, priv);
>> + if (reg) {
>> + refcount_inc(&ref->refcount);
>> + return 0;
>> + }
>> + ref_exists = true;
>> + break;
>> + }
>> +
>> + if (!ref_exists) {
>> + ref = kzalloc(sizeof(*ref), GFP_KERNEL);
>> + if (!ref)
>> + return -ENOMEM;
>> + ref->pin = pin;
>> + INIT_LIST_HEAD(&ref->registration_list);
>> + ret = xa_insert(xa_pins, pin->pin_idx, ref, GFP_KERNEL);
>> + if (ret) {
>> + kfree(ref);
>> + return ret;
>> + }
>> + refcount_set(&ref->refcount, 1);
>> + }
>> +
>> + reg = kzalloc(sizeof(*reg), GFP_KERNEL);
>
>Why do we have two structures - ref and reg?
>
Thank to Jiri and reg struct we solved a pin/dpll association
with multiple device drivers..
I.e. for pin:
struct dpll_pin_registration {
struct list_head list;
const struct dpll_pin_ops *ops;
void *priv;
};
struct dpll_pin_ref {
union {
struct dpll_device *dpll;
struct dpll_pin *pin;
};
struct list_head registration_list;
refcount_t refcount;
};
struct dpll_pin {
u32 id;
u32 pin_idx;
u64 clock_id;
struct module *module;
struct xarray dpll_refs;
struct xarray parent_refs;
const struct dpll_pin_properties *prop;
char *rclk_dev_name;
refcount_t refcount;
};
Basically, a pin or a device can be registered from multiple drivers,
where each driver has own priv and ops.
A single dpll_pin has references to dplls or pins (dpll_refs/parent_refs)
it is connected with, and thanks to registration list single reference can
have multiple drivers being attached with a particular dpll/pin.
The same scheme is for a dpll_device struct and associated pins.
>> + if (!reg) {
>> + if (!ref_exists)
>> + kfree(ref);
>
>ref has already been inserted into xa_pins
>
True, seems like a bug, will fix it.
Thank you,
Arkadiusz
>> + return -ENOMEM;
