Re: [PATCH v1 04/16] thunderbolt: ACPI: Use acpi_find_child_by_adr()

Heikki Krogerus
2022-06-10T06:46:36Z

On Thu, Jun 09, 2022 at 03:54:40PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Instead of walking the list of children of an ACPI device directly
> in order to find the child matching a given bus address, use
> acpi_find_child_by_adr() for this purpose.
>
> Apart from simplifying the code, this will help to eliminate the
> children list head from struct acpi_device as it is redundant and it
> is used in questionable ways in some places (in particular, locking is
> needed for walking the list pointed to it safely, but it is often
> missing).
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> drivers/thunderbolt/acpi.c | 9 +--------
> 1 file changed, 1 insertion(+), 8 deletions(-)
>
> Index: linux-pm/drivers/thunderbolt/acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/thunderbolt/acpi.c
> +++ linux-pm/drivers/thunderbolt/acpi.c
> @@ -304,8 +304,6 @@ static bool tb_acpi_bus_match(struct dev
> static struct acpi_device *tb_acpi_find_port(struct acpi_device *adev,
> const struct tb_port *port)
> {
> - struct acpi_device *port_adev;
> -
> if (!adev)
> return NULL;
>
> @@ -313,12 +311,7 @@ static struct acpi_device *tb_acpi_find_
> * Device routers exists under the downstream facing USB4 port
> * of the parent router. Their _ADR is always 0.
> */
> - list_for_each_entry(port_adev, &adev->children, node) {
> - if (acpi_device_adr(port_adev) == port->port)
> - return port_adev;
> - }
> -
> - return NULL;
> + return acpi_find_child_by_adr(adev, port->port);
> }
>
> static struct acpi_device *tb_acpi_switch_find_companion(struct tb_switch *sw)

I don't think you need tb_acpi_find_port() anymore. You can just call
acpi_find_child_by_ard(ACPI_COMPANION(...), port->port) directly, no?

thanks,

--
heikki