All available downstream ports - physical and logical - are exposed for
each MST device. They are listed in /dev/, following the same naming
scheme as SST devices by appending an incremental ID.
Although all downstream ports are exposed, only some will work as
expected. Consider the following topology:
+---------+
| ASIC |
+---------+
Conn-0|
|
+----v----+
+----| MST HUB |----+
| +---------+ |
| |
|Port-1 Port-2|
+-----v-----+ +-----v-----+
| MST | | SST |
| Display | | Display |
+-----------+ +-----------+
|Port-1
x
MST Path | MST Device
----------+----------------------------------
sst:0 | MST Hub
mst:0-1 | MST Display
mst:0-1-1 | MST Display's disconnected DP out
mst:0-1-8 | MST Display's internal sink
mst:0-2 | SST Display
On certain MST displays, the upstream physical port will ACK DPCD reads.
However, reads on the local logical port to the internal sink will
*NAK*. i.e. reading mst:0-1 ACKs, but mst:0-1-8 NAKs.
There may also be duplicates. Some displays will return the same GUID
when reading DPCD from both mst:0-1 and mst:0-1-8.
There are some device-dependent behavior as well. The MST hub used
during testing will actually *ACK* read requests on a disconnected
physical port, whereas the MST displays will NAK.
In light of these discrepancies, it's simpler to expose all downstream
ports - both physical and logical - and let the user decide what to use.
v3 changes:
* Change WARN_ON_ONCE -> DRM_ERROR on dpcd read errors
* Docstring and cosmetic fixes
v2 changes:
Moved remote aux device (un)registration to new mst connector late
register and early unregister helpers. Drivers should call these from
their own mst connector function hooks.
This is to solve an issue during driver unload, where mst connector
devices are unregistered before the remote aux devices are. In a setup
where aux devices are created as children of connector devices, the aux
device would be removed too early, and uncleanly. Doing so in
early_unregister solves this issue, as that is called before connector
unregistration.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190723232808.28128-3-sunpeng.li@amd.com
In preparation for adding aux devices for DP MST, make the IDR
non-cyclic. That way, hotplug cycling MST devices won't needlessly
increment the minor version index.
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190723232808.28128-2-sunpeng.li@amd.com
The old wait_on_atomic_t() is going to get removed, use the more
flexible wait_var_event() API instead.
Unlike wake_up_atomic_t(), wake_up_var() will issue the wakeup
even if the variable is not 0.
No change in functionality.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Make wait_on_atomic_t() pass the TASK_* mode onto its action function as an
extra argument and make it 'unsigned int throughout.
Also, consolidate a bunch of identical action functions into a default
function that can do the appropriate thing for the mode.
Also, change the argument name in the bit_wait*() function declarations to
reflect the fact that it's the mode and not the bit number.
[Peter Z gives this a grudging ACK, but thinks that the whole atomic_t wait
should be done differently, though he's not immediately sure as to how]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
cc: Ingo Molnar <mingo@kernel.org>
They're only used internally within the dp helpers. Also nuke the
kerneldoc (we only document the driver interface in the drm shared
functions). And move the header file from the public include/
directory to the source files into drm_crtc_helper_internal.h, similar
to how we already have drm_crtc_internal.h.
While at it also move drm_fb_helper_modinit since that belongs in
there, too.
I noticed this all since I spotted kerneldoc which wasn't pulled into
the rst templates.
v2: Update Copyright date.
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471034937-651-16-git-send-email-daniel.vetter@ffwll.ch
Let's be nice and interrupt the dpcd aux-dev reads/writes when there's
a signal pending. Much nicer if the user can hit ^C instead of having to
sit around waiting for the read/write to finish.
time dd if=/dev/drm_dp_aux0 bs=$((1024*1024))
^C
before:
real 0m34.681s
user 0m0.003s
sys 0m6.880s
after:
real 0m0.222s
user 0m0.006s
sys 0m0.057s
Cc: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461786225-7790-1-git-send-email-ville.syrjala@linux.intel.com
This module is heavily based on i2c-dev. Once loaded, it provides one
dev node per DP AUX channel, named drm_dp_auxN, where N is an integer.
It's possible to know which connector owns this aux channel by looking
at the respective sysfs /sys/class/drm_aux_dev/drm_dp_auxN/connector, if
the connector device pointer was correctly set in the aux helper struct.
Two main operations are provided on the registers read and write. The
address of the register to be read or written is given using lseek. The
seek position is updated upon read or write.
v2:
- lseek is used to select the register to read/write
- read/write are used instead of ioctl
- no blocking_notifier is used, just a direct callback
v3:
- use drm_dp_aux_dev prefix for public functions
- chardev is named drm_dp_auxN
- read/write don't allocate a buffer anymore, and transfer up to 16 bytes a
time
- remove notifier list from the implementation
- option on menuconfig is now a boolean
- add inline stub functions to avoid breakage when this option is disabled
v4:
- fix build system changes - actually disable this module when not selected.
v5:
- Use kref to avoid device closing while still in use
- Don't use list, use an idr for storing aux_dev
- Remove "connector" attribute
- set aux.dev to the connector drm_connector device, instead of
drm_device
v6:
- Use atomic_t for usage count
- Use a mutex instead of spinlock for idr lock
- Destroy chardev immediately on unregister
- other minor suggestions from Ville
v7:
- style fixes
- error handling fixes
v8:
- more error handling fixes
v9:
- remove module_init and module_exit, and add drm_dp_aux_dev_init/exit
to drm_kms_helper_init/exit.
Signed-off-by: Rafael Antognolli <rafael.antognolli@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1453417821-2811-3-git-send-email-rafael.antognolli@intel.com
Ville Syrjälä