> -Original Message-
> From: Intel-gfx On Behalf Of Imre
> Deak
> Sent: Wednesday, February 21, 2024 2:49 AM
> To: intel-...@lists.freedesktop.org; dri-devel@lists.freedesktop.org
> Cc: Ville Syrjälä
> Subject: [PATCH v2 12/21] drm/i915/dp: Add support for DP tunnel BW allocation
>
> Add support to enable the DP tunnel BW allocation mode. Follow-up patches will
> call the required helpers added here to prepare for a modeset on a link with
> DP
> tunnels, the last change in the patchset actually enabling BWA.
>
> With BWA enabled, the driver will expose the full mode list a display
> supports,
> regardless of any BW limitation on a shared (Thunderbolt) link. Such BW
> limits will
> be checked against only during a modeset, when the driver has the full
> knowledge
> of each display's BW requirement.
>
> If the link BW changes in a way that a connector's modelist may also change,
> userspace will get a hotplug notification for all the connectors sharing the
> same
> link (so it can adjust the mode used for a display).
>
> The BW limitation can change at any point, asynchronously to modesets on a
> given connector, so a modeset can fail even though the atomic check for it
> passed. In such scenarios userspace will get a bad link notification and in
> response is supposed to retry the modeset.
>
> v2:
> - Fix old vs. new connector state in intel_dp_tunnel_atomic_check_state().
> (Ville)
> - Fix propagating the error from
> intel_dp_tunnel_atomic_compute_stream_bw(). (Ville)
> - Move tunnel==NULL checks from driver to DRM core helpers. (Ville)
> - Simplify return flow from intel_dp_tunnel_detect(). (Ville)
> - s/dp_tunnel_state/inherited_dp_tunnels (Ville)
> - Simplify struct intel_dp_tunnel_inherited_state. (Ville)
> - Unconstify object pointers (vs. states) where possible. (Ville)
> - Init crtc_state while declaring it in check_group_state(). (Ville)
> - Join obj->base.id, obj->name arg lines in debug prints to reduce LOC.
> (Ville)
> - Add/rework intel_dp_tunnel_atomic_alloc_bw() to prepare for moving the
> BW allocation from encoder hooks up to intel_atomic_commit_tail()
> later in the patchset.
> - Disable BW alloc mode during system suspend.
> - Allocate the required BW for all tunnels during system resume.
> - Add intel_dp_tunnel_atomic_clear_stream_bw() instead of the open-coded
> sequence in a follow-up patch.
> - Add function documentation to all exported functions.
> - Add CONFIG_USB4 dependency to CONFIG_DRM_I915_DP_TUNNEL.
Changes look good to me.
Reviewed-by: Uma Shankar
> Cc: Ville Syrjälä
> Signed-off-by: Imre Deak
> ---
> drivers/gpu/drm/i915/Kconfig | 14 +
> drivers/gpu/drm/i915/Kconfig.debug| 1 +
> drivers/gpu/drm/i915/Makefile | 3 +
> drivers/gpu/drm/i915/display/intel_atomic.c | 2 +
> drivers/gpu/drm/i915/display/intel_crtc.c | 25 +
> drivers/gpu/drm/i915/display/intel_crtc.h | 1 +
> .../gpu/drm/i915/display/intel_display_core.h | 1 +
> .../drm/i915/display/intel_display_types.h| 9 +
> .../gpu/drm/i915/display/intel_dp_tunnel.c| 815 ++
> .../gpu/drm/i915/display/intel_dp_tunnel.h| 133 +++
> 10 files changed, 1004 insertions(+)
> create mode 100644 drivers/gpu/drm/i915/display/intel_dp_tunnel.c
> create mode 100644 drivers/gpu/drm/i915/display/intel_dp_tunnel.h
>
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig index
> 3089029abba48..5932024f8f954 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -155,6 +155,20 @@ config DRM_I915_PXP
> protected session and manage the status of the alive software session,
> as well as its life cycle.
>
> +config DRM_I915_DP_TUNNEL
> + bool "Enable DP tunnel support"
> + depends on DRM_I915
> + depends on USB4
> + select DRM_DISPLAY_DP_TUNNEL
> + default y
> + help
> + Choose this option to detect DP tunnels and enable the Bandwidth
> + Allocation mode for such tunnels. This allows using the maximum
> + resolution allowed by the link BW on all displays sharing the
> + link BW, for instance on a Thunderbolt link.
> +
> + If in doubt, say "Y".
> +
> menu "drm/i915 Debugging"
> depends on DRM_I915
> depends on EXPERT
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug
> b/drivers/gpu/drm/i915/Kconfig.debug
> index 5b7162076850c..bc18e2d9ea05d 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -28,6 +28,7 @@ config DRM_I915_DEBUG
> select STACKDEPOT
> select STACKTRACE
> select DRM_DP_AUX_CHARDEV
> + select DRM_DISPLAY_DEBUG_DP_TUNNEL_STATE if
> DRM_I915_DP_TUNNEL
> select X86_MSR # used by igt/pm_rpm
> select DRM_VGEM # used by igt/prime_vgem (dmabuf interop checks)
> select DRM_DEBUG_MM if DRM=y
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index
