kernel/linux.git/drivers/gpu/drm/drm_dp_cec.c, branch v5.10.264

gpu: drm_dp_cec: fix broken CEC adapter properties check

2025-03-13T11:47:04+00:00

[ Upstream commit 6daaae5ff7f3b23a2dacc9c387ff3d4f95b67cad ] If the hotplug detect of a display is low for longer than one second (configurable through drm_dp_cec_unregister_delay), then the CEC adapter is unregistered since we assume the display was disconnected. If the HPD went low for less than one second, then we check if the properties of the CEC adapter have changed, since that indicates that we actually switch to new hardware and we have to unregister the old CEC device and register a new one. Unfortunately, the test for changed properties was written poorly, and after a new CEC capability was added to the CEC core code the test always returned true (i.e. the properties had changed). As a result the CEC device was unregistered and re-registered for every HPD toggle. If the CEC remote controller integration was also enabled (CONFIG_MEDIA_CEC_RC was set), then the corresponding input device was also unregistered and re-registered. As a result the input device in /sys would keep incrementing its number, e.g.: /sys/devices/pci0000:00/0000:00:08.1/0000:e7:00.0/rc/rc0/input20 Since short HPD toggles are common, the number could over time get into the thousands. While not a serious issue (i.e. nothing crashes), it is not intended to work that way. This patch changes the test so that it only checks for the single CEC capability that can actually change, and it ignores any other capabilities, so this is now safe as well if new caps are added in the future. With the changed test the bit under #ifndef CONFIG_MEDIA_CEC_RC can be dropped as well, so that's a nice cleanup. Signed-off-by: Hans Verkuil Reported-by: Farblos Reviewed-by: Dmitry Baryshkov Fixes: 2c6d1fffa1d9 ("drm: add support for DisplayPort CEC-Tunneling-over-AUX") Tested-by: Farblos Link: https://patchwork.freedesktop.org/patch/msgid/361bb03d-1691-4e23-84da-0861ead5dbdc@xs4all.nl Signed-off-by: Dmitry Baryshkov Signed-off-by: Sasha Levin

drm_dp_cec: drop use of drmP.h

2019-10-08T16:29:00+00:00

drmP.h is deprecated and will be deleted. Replace use with proper header. Divide header includes in blocks while touching these. Build tested with various archtectures and configs. Signed-off-by: Sam Ravnborg Fixes: ae85b0df124f6928 ("drm_dp_cec: add connector info support.") Reviewed-by: Lyude Paul Reviewed-by: Sean Paul Acked-by: Hans Verkuil Cc: Dariusz Marcinkiewicz Cc: Ben Skeggs Link: https://patchwork.freedesktop.org/patch/msgid/20191007171224.1581-2-sam@ravnborg.org

drm_dp_cec: add connector info support.

2019-08-27T10:52:59+00:00

Pass the connector info to the CEC adapter. This makes it possible to associate the CEC adapter with the corresponding drm connector. Signed-off-by: Dariusz Marcinkiewicz Signed-off-by: Hans Verkuil Tested-by: Hans Verkuil Reviewed-by: Lyude Paul Reviewed-by: Ben Skeggs Signed-off-by: Hans Verkuil Link: https://patchwork.freedesktop.org/patch/msgid/20190814104520.6001-2-darekm@google.com

drm: Do not call drm_dp_cec_set_edid() while registering DP connectors

2018-10-11T08:52:35+00:00

drm_dp_cec_register_connector() is called when registering each DP connector in DRM, while sounds a good idea register CEC adapters as earlier as possible, it causes some driver initialization delay trying to do DPCD transactions in disconnected connectors. This change will cause no regressions as drm_dp_cec_set_edid() will still be called in further detection of connected connectors with a valid edid parameter. This change reduced the module load of i915 by average 0.5sec in a machine with just one DP port disconnected while reducing more than 3sec in a machine with 4 DP ports disconnected. Cc: Hans Verkuil Signed-off-by: José Roberto de Souza Acked-by: Hans Verkuil Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20181011004439.4482-1-jose.souza@intel.com

drm_dp_cec: add note about good MegaChips 2900 CEC support

2018-08-31T08:20:38+00:00

A big problem with DP CEC-Tunneling-over-AUX is that it is tricky to find adapters with a chipset that supports this AND where the manufacturer actually connected the HDMI CEC line to the chipset. Add a mention of the MegaChips 2900 chipset which seems to support this feature well. Signed-off-by: Hans Verkuil Reviewed-by: Lyude Paul Acked-by: Alex Deucher Link: https://patchwork.freedesktop.org/patch/msgid/20180827075820.41109-3-hverkuil@xs4all.nl

drm_dp_cec: check that aux has a transfer function

2018-08-31T08:20:37+00:00

If aux->transfer == NULL, then just return without doing anything. In that case the function is likely called for a non-(e)DP connector. This never happened for the i915 driver, but the nouveau and amdgpu drivers need this check. The alternative would be to add this check in those drivers before every drm_dp_cec call, but it makes sense to check it in the drm_dp_cec functions to prevent a kernel oops. Signed-off-by: Hans Verkuil Reviewed-by: Lyude Paul Acked-by: Alex Deucher Link: https://patchwork.freedesktop.org/patch/msgid/20180827075820.41109-2-hverkuil@xs4all.nl

drm_dp_cec.c: fix formatting typo: %pdH -> %phD

2018-07-28T18:50:40+00:00

This caused a kernel oops since %pdH interpreted the pointer as a struct file. Signed-off-by: Hans Verkuil Signed-off-by: Gustavo Padovan Link: https://patchwork.freedesktop.org/patch/msgid/f3720ddf-ec0f-cd22-46b6-720a5e2098f2@xs4all.nl

drm: add support for DisplayPort CEC-Tunneling-over-AUX

2018-07-13T14:58:19+00:00

This adds support for the DisplayPort CEC-Tunneling-over-AUX feature that is part of the DisplayPort 1.3 standard. Unfortunately, not all DisplayPort/USB-C to HDMI adapters with a chip that has this capability actually hook up the CEC pin, so even though a CEC device is created, it may not actually work. Signed-off-by: Hans Verkuil Reviewed-by: Ville Syrjälä Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20180711132909.25409-2-hverkuil@xs4all.nl