From: Saravana Kannan saravanak@google.com
[ Upstream commit 67cad5c67019c38126b749621665b6723d3ae7e6 ]
fw_devlink uses DL_FLAG_SYNC_STATE_ONLY device link flag for two purposes:
1. To allow a parent device to proxy its child device's dependency on a supplier so that the supplier doesn't get its sync_state() callback before the child device/consumer can be added and probed. In this usage scenario, we need to ignore cycles for ensure correctness of sync_state() callbacks.
2. When there are dependency cycles in firmware, we don't know which of those dependencies are valid. So, we have to ignore them all wrt probe ordering while still making sure the sync_state() callbacks come correctly.
However, when detecting dependency cycles, there can be multiple dependency cycles between two devices that we need to detect. For example:
A -> B -> A and A -> C -> B -> A.
To detect multiple cycles correct, we need to be able to differentiate DL_FLAG_SYNC_STATE_ONLY device links used for (1) vs (2) above.
To allow this differentiation, add a DL_FLAG_CYCLE that can be use to mark use case (2). We can then use the DL_FLAG_CYCLE to decide which DL_FLAG_SYNC_STATE_ONLY device links to follow when looking for dependency cycles.
Fixes: 2de9d8e0d2fe ("driver core: fw_devlink: Improve handling of cyclic dependencies") Signed-off-by: Saravana Kannan saravanak@google.com Tested-by: Colin Foster colin.foster@in-advantage.com Tested-by: Sudeep Holla sudeep.holla@arm.com Tested-by: Douglas Anderson dianders@chromium.org Tested-by: Geert Uytterhoeven geert+renesas@glider.be Tested-by: Luca Weiss luca.weiss@fairphone.com # qcom/sm7225-fairphone-fp4 Link: https://lore.kernel.org/r/20230207014207.1678715-6-saravanak@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/core.c | 28 ++++++++++++++++++---------- include/linux/device.h | 1 + 2 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c index adf003a7e8d6a..178a21e985197 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -269,6 +269,12 @@ static bool device_is_ancestor(struct device *dev, struct device *target) return false; }
+static inline bool device_link_flag_is_sync_state_only(u32 flags) +{ + return (flags & ~(DL_FLAG_INFERRED | DL_FLAG_CYCLE)) == + (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED); +} + /** * device_is_dependent - Check if one device depends on another one * @dev: Device to check dependencies for. @@ -295,8 +301,7 @@ int device_is_dependent(struct device *dev, void *target) return ret;
list_for_each_entry(link, &dev->links.consumers, s_node) { - if ((link->flags & ~DL_FLAG_INFERRED) == - (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED)) + if (device_link_flag_is_sync_state_only(link->flags)) continue;
if (link->consumer == target) @@ -369,8 +374,7 @@ static int device_reorder_to_tail(struct device *dev, void *not_used)
device_for_each_child(dev, NULL, device_reorder_to_tail); list_for_each_entry(link, &dev->links.consumers, s_node) { - if ((link->flags & ~DL_FLAG_INFERRED) == - (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED)) + if (device_link_flag_is_sync_state_only(link->flags)) continue; device_reorder_to_tail(link->consumer, NULL); } @@ -621,7 +625,8 @@ postcore_initcall(devlink_class_init); DL_FLAG_AUTOREMOVE_SUPPLIER | \ DL_FLAG_AUTOPROBE_CONSUMER | \ DL_FLAG_SYNC_STATE_ONLY | \ - DL_FLAG_INFERRED) + DL_FLAG_INFERRED | \ + DL_FLAG_CYCLE)
#define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \ DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE) @@ -690,8 +695,6 @@ struct device_link *device_link_add(struct device *consumer, if (!consumer || !supplier || consumer == supplier || flags & ~DL_ADD_VALID_FLAGS || (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) || - (flags & DL_FLAG_SYNC_STATE_ONLY && - (flags & ~DL_FLAG_INFERRED) != DL_FLAG_SYNC_STATE_ONLY) || (flags & DL_FLAG_AUTOPROBE_CONSUMER && flags & (DL_FLAG_AUTOREMOVE_CONSUMER | DL_FLAG_AUTOREMOVE_SUPPLIER))) @@ -707,6 +710,10 @@ struct device_link *device_link_add(struct device *consumer, if (!(flags & DL_FLAG_STATELESS)) flags |= DL_FLAG_MANAGED;
+ if (flags & DL_FLAG_SYNC_STATE_ONLY && + !device_link_flag_is_sync_state_only(flags)) + return NULL; + device_links_write_lock(); device_pm_lock();
@@ -1627,7 +1634,7 @@ static void fw_devlink_relax_link(struct device_link *link) if (!(link->flags & DL_FLAG_INFERRED)) return;
- if (link->flags == (DL_FLAG_MANAGED | FW_DEVLINK_FLAGS_PERMISSIVE)) + if (device_link_flag_is_sync_state_only(link->flags)) return;
pm_runtime_drop_link(link); @@ -1695,8 +1702,8 @@ static int fw_devlink_relax_cycle(struct device *con, void *sup) return ret;
list_for_each_entry(link, &con->links.consumers, s_node) { - if ((link->flags & ~DL_FLAG_INFERRED) == - (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED)) + if (!(link->flags & DL_FLAG_CYCLE) && + device_link_flag_is_sync_state_only(link->flags)) continue;
if (!fw_devlink_relax_cycle(link->consumer, sup)) @@ -1705,6 +1712,7 @@ static int fw_devlink_relax_cycle(struct device *con, void *sup) ret = 1;
fw_devlink_relax_link(link); + link->flags |= DL_FLAG_CYCLE; } return ret; } diff --git a/include/linux/device.h b/include/linux/device.h index e270cb740b9e7..636ef7caa021d 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -326,6 +326,7 @@ enum device_link_state { #define DL_FLAG_MANAGED BIT(6) #define DL_FLAG_SYNC_STATE_ONLY BIT(7) #define DL_FLAG_INFERRED BIT(8) +#define DL_FLAG_CYCLE BIT(9)
/** * enum dl_dev_state - Device driver presence tracking information.