Badhri Jagan Sridharan 7561e7c29c FROMGIT: usb: typec: tcpm: Introduce vsafe0v for vbus
TCPM at present lacks the notion of VSAFE0V. There
are three vbus threshold levels that are critical to track:
a. vSafe5V         - VBUS “5 volts” as defined by the USB
                     PD specification.
b. vSinkDisconnect - Threshold used for transition from
                     Attached.SNK to Unattached.SNK.
c. vSafe0V         - VBUS “0 volts” as defined by the USB
                     PD specification.

Tracking vSafe0V is crucial for entry into Try.SNK and
Attached.SRC and turning vbus back on by the source in
response to hard reset.

From "4.5.2.2.8.2 Exiting from AttachWait.SRC State" section
in the Type-C spec:

"The port shall transition to Attached.SRC when VBUS is at
vSafe0V and the SRC.Rd state is detected on exactly one of
the CC1 or CC2 pins for at least tCCDebounce."

"A DRP that strongly prefers the Sink role may optionally
transition to Try.SNK instead of Attached.SRC when VBUS
is at vSafe0V and the SRC.Rd state is detected on exactly
one of the CC1 or CC2 pins for at least tCCDebounce."

From "7.1.5 Response to Hard Resets" section in the PD spec:

"After establishing the vSafe0V voltage condition on VBUS,
the Source Shall wait tSrcRecover before re-applying VCONN
and restoring VBUS to vSafe5V."

vbus_present in the TCPM code tracks vSafe5V(vbus_present is true)
and vSinkDisconnect(vbus_present is false).

This change adds is_vbus_vsafe0v callback which when set makes
TCPM query for vSafe0V voltage level when needed.

Since not all TCPC controllers might have the capability
to report vSafe0V, TCPM assumes that vSafe0V is same as
vSinkDisconnect when is_vbus_vsafe0v callback is not set.
This allows TCPM to continue to support controllers which don't
have the support for reporting vSafe0V.

Introducing vSafe0V helps fix the failure reported at
"Step 15. CVS verifies PUT remains in AttachWait.SRC for 500ms"
of "TD 4.7.2 Try. SNK DRP Connect DRP Test" of
"Universal Serial Bus Type-C (USB Type-C) Functional Test
Specification Chapters 4 and 5". Here the compliance tester
intentionally maintains vbus at greater than vSafe0V and expects
the Product under test to stay in AttachWait.SRC till vbus drops
to vSafe0V.

Bug: 173747861
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20201202040840.663578-1-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 28b43d3d74 usb-next)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I2386cd38d8355dc700f00919bbe7f1132f5041d6
2020-12-09 15:02:41 +01:00
2020-12-09 08:09:26 +01:00
2020-12-09 08:09:26 +01:00
2020-12-09 08:09:26 +01:00
2020-12-09 08:09:26 +01:00
2020-12-09 08:09:26 +01:00
2020-12-09 08:09:26 +01:00

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

    • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux, additions of EXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export.
    • When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.
  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass script/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry picked from commit ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry picked from commit ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [joe: Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • add a Bug: tag with the Android bug (required for patches not accepted into a maintainer tree)
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)
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