From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
To: David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
Andy Gross <agross@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
Vinod Koul <vkoul@kernel.org>,
Kishon Vijay Abraham I <kishon@kernel.org>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Neil Armstrong <neil.armstrong@linaro.org>
Cc: dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
linux-phy@lists.infradead.org, linux-usb@vger.kernel.org
Subject: [PATCH 0/3] drm/display: simplify support for transparent DRM bridges
Date: Sat, 29 Jul 2023 23:43:04 +0300 [thread overview]
Message-ID: <20230729204307.268587-1-dmitry.baryshkov@linaro.org> (raw)
Supporting DP/USB-C can result in a chain of several transparent
bridges (PHY, redrivers, mux, etc). This results in drivers having
similar boilerplate code for such bridges.
Next, these drivers are susceptible to -EPROBE_DEFER loops: the next
bridge can either be probed from the bridge->attach callback, when it is
too late to return -EPROBE_DEFER, or from the probe() callback, when the
next bridge might not yet be available, because it depends on the
resources provided by the probing device.
Last, but not least, this results in the the internal knowledge of DRM
subsystem slowly diffusing into other subsystems, like PHY or USB/TYPEC.
To solve all these issues, define a separate DRM helper, which creates
separate aux device just for the bridge. During probe such aux device
doesn't result in the EPROBE_DEFER loops. Instead it allows the device
drivers to probe properly, according to the actual resource
dependencies. The bridge auxdevs are then probed when the next bridge
becomes available, sparing drivers from drm_bridge_attach() returning
-EPROBE_DEFER.
Proposed merge strategy: immutable branch with the drm commit, which is
then merged into PHY and USB subsystems together with the corresponding
patch.
Dmitry Baryshkov (3):
drm/display: add transparent bridge helper
phy: qcom: qmp-combo: switch to DRM_SIMPLE_BRIDGE
usb: typec: nb7vpq904m: switch to DRM_SIMPLE_BRIDGE
drivers/gpu/drm/display/Kconfig | 9 ++
drivers/gpu/drm/display/Makefile | 2 +
drivers/gpu/drm/display/drm_simple_bridge.c | 120 ++++++++++++++++++++
drivers/phy/qualcomm/Kconfig | 3 +-
drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 44 +------
drivers/usb/typec/mux/Kconfig | 3 +-
drivers/usb/typec/mux/nb7vpq904m.c | 44 +------
include/drm/display/drm_simple_bridge.h | 19 ++++
8 files changed, 156 insertions(+), 88 deletions(-)
create mode 100644 drivers/gpu/drm/display/drm_simple_bridge.c
create mode 100644 include/drm/display/drm_simple_bridge.h
--
2.39.2
--
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy
next reply other threads:[~2023-07-29 20:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-29 20:43 Dmitry Baryshkov [this message]
2023-07-29 20:43 ` [PATCH 1/3] drm/display: add transparent bridge helper Dmitry Baryshkov
2023-07-29 23:06 ` Dmitry Baryshkov
2023-07-29 20:43 ` [PATCH 2/3] phy: qcom: qmp-combo: switch to DRM_SIMPLE_BRIDGE Dmitry Baryshkov
2023-07-30 7:57 ` kernel test robot
2023-07-29 20:43 ` [PATCH 3/3] usb: typec: nb7vpq904m: " Dmitry Baryshkov
2023-07-29 23:04 ` kernel test robot
2023-07-30 1:08 ` kernel test robot
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