7 Mar
2023
7 Mar
'23
9:25 p.m.
On 07/03/23 20:58, Pierre-Louis Bossart wrote:
+static int amd_resume_child_device(struct device *dev, void *data) +{
- struct sdw_slave *slave = dev_to_sdw_dev(dev);
- int ret;
- if (!slave->probed) {
dev_dbg(dev, "skipping device, no probed driver\n");return 0;- }
- if (!slave->dev_num_sticky) {
dev_dbg(dev, "skipping device, never detected on bus\n");return 0;- }
- if (!pm_runtime_suspended(dev))
return 0;- ret = pm_request_resume(dev);
I still don't get why the test above was needed. It's racy and brings limited benefits.
As explained below thread,
https://lore.kernel.org/lkml/acd3a560-1218-9f1d-06ec-19e4d3d4e2c9@amd.com
Our scenario is multiple peripheral devices are connected over the same link.
In our implementation, device_for_each_child() function invokes amd_resume_child_device callback for each child. When any one of the child device is active, It will break the iteration, which results in failure resuming all child devices.
If we skip , pm_suspended check , it will not resume all peripheral devices when any one of the peripheral device is active.
- if (ret < 0)
dev_err(dev, "pm_request_resume failed: %d\n", ret);- return ret;
+}