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| author | Saravana Kannan <saravanak@google.com> | 2023-02-07 04:41:57 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-02-08 15:37:54 +0300 |
| commit | 67cad5c67019c38126b749621665b6723d3ae7e6 (patch) | |
| tree | be019064eaecfb2fda50fc474b232fc0e7763881 /include/linux/device.h | |
| parent | 38dfa56b3db354b4bd399fc686c3e74ad32ffa57 (diff) | |
| download | linux-67cad5c67019c38126b749621665b6723d3ae7e6.tar.xz | |
driver core: fw_devlink: Add DL_FLAG_CYCLE support to device links
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>
Diffstat (limited to 'include/linux/device.h')
| -rw-r--r-- | include/linux/device.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/device.h b/include/linux/device.h index 90aaf308c259..1508e637bb26 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -328,6 +328,7 @@ 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. |