STRUCT DPU_ENCODER_VIRT(9)

📦 version 7.3.1, in nixpkgs unstable

💅 struct dpu_encoder_virt(9) — the kernel API manual, but make it make sense

okay so bestie, welcome to the struct dpu_encoder_virt(9) page from the Kernel API Manual 💖 this one lives in ./drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c and honestly? it's giving "main character of the display pipeline" energy, no cap.

✨ NAME ✨

struct dpu_encoder_virt — the virtual encoder, aka the container of one or more physical encoders. 🫶

The virtual encoder manages exactly one "logical" display. The physical encoders each manage one intf block, and each one is tied to a specific panel/sub-panel. The virtual encoder defers as much as possible to the physical encoders (she delegates, she's a manager 💅), and she registers herself with the DRM Framework as the encoder. Periodt.

🌈 SYNOPSIS 🌈

struct dpu_encoder_virt {
    struct drm_encoder base;
    spinlock_t enc_spinlock;
    bool enabled;
    bool commit_done_timedout;
    unsigned int num_phys_encs;
    struct dpu_encoder_phys *phys_encs[MAX_PHYS_ENCODERS_PER_VIRTUAL];
    struct dpu_encoder_phys *cur_master;
    struct dpu_encoder_phys *cur_slave;
    struct dpu_hw_pingpong *hw_pp[MAX_CHANNELS_PER_ENC];
    struct dpu_hw_cwb *hw_cwb[MAX_CWB_PER_ENC];
    struct dpu_hw_dsc *hw_dsc[MAX_CHANNELS_PER_ENC];
    unsigned int dsc_mask;
    unsigned int cwb_mask;
    bool intfs_swapped;
    struct drm_crtc *crtc;
    struct drm_connector *connector;
    struct mutex enc_lock;
    unsigned long frame_busy_mask[BITS_TO_LONGS(MAX_PHYS_ENCODERS_PER_VIRTUAL)];
    atomic_t frame_done_timeout_ms;
    atomic_t frame_done_timeout_cnt;
    struct timer_list frame_done_timer;
    struct msm_display_info disp_info;
    bool idle_pc_supported;
    struct mutex rc_lock;
    enum dpu_enc_rc_states rc_state;
    struct delayed_work delayed_off_work;
    struct msm_display_topology topology;
    u32 idle_timeout;
    bool wide_bus_en;
    struct drm_dsc_config *dsc;
};

🎀 Members 🎀

okay here's the whole cast, one by one, and yes I'm gonna introduce every single one because they all ate 💖

  • base — the drm_encoder base class, for registration with DRM. literally her legal name for the framework.
  • enc_spinlock — Virtual-Encoder-Wide Spin Lock for IRQ purposes. one lock to rule the interrupts ✨
  • enabled — True if the encoder is active, protected by enc_lock. (emphasis on protected, bestie 🔒)
  • commit_done_timedout — True if there has been a timeout on commit after enabling the encoder. 😭 she timed out, it happens.
  • num_phys_encs — the actual number of physical encoders contained. the real count, not the vibe count.
  • phys_encs — the container of physical encoders managed. her whole friend group 🫶
  • cur_master — pointer to the current master in this mode. Optimization. Only valid after enable, and cleared as disable. so like, only valid while she's on 👑
  • cur_slave — as above but for the slave encoder. matching set, iconic.
  • hw_pp — handle to the pingpong blocks used for the display. Ngl, the number of pingpong blocks can be different than num_phys_encs. don't assume, k?
  • hw_cwb — handle to the CWB muxes used for concurrent writeback display. The number of CWB muxes can be different than num_phys_encs too. same energy as above fr fr.
  • hw_dsc — handle to the DSC blocks used for the display.
  • dsc_mask — bitmask of used DSC blocks. 🎯
  • cwb_mask — bitmask of used CWB muxes.
  • intfs_swapped — whether or not the phys_enc interfaces have been swapped for partial update right-only cases, such as pingpong split where virtual pingpong does not generate IRQs. (iykyk 💀)
  • crtc — pointer to the currently assigned crtc. Normally you would use crtc->state->encoder_mask to determine the link between encoder/crtc — BUT in this case we need to track crtc in the disable hook, which is called _after_ encoder_mask is cleared. so yeah, she has to remember things herself. lowkey relatable.
  • connector — if a mode is set, a cached pointer to the active connector. caching queen 🧚
  • enc_lock — lock around physical encoder create/destroy/enable/disable. the bouncer at the door.
  • frame_busy_mask — bitmask tracking which phys_enc we are still busy processing current command. Bit0 = phys_encs[0] etc.
  • frame_done_timeout_ms — frame done timeout in ms. ⏱️
  • frame_done_timeout_cnt — atomic counter tracking the number of frame done timeouts. yes we're counting them. 💀
  • frame_done_timer — watchdog timer for frame done event. she's watching 👀
  • disp_info — local copy of msm_display_info struct.
  • idle_pc_supported — indicate if idle power collaps is supported.
  • rc_lock — resource control mutex lock to protect virt encoder over various state changes. very demure, very mindful locking.
  • rc_state — resource controller state.
  • delayed_off_work — delayed worker to schedule disabling of clks and resources after IDLE_TIMEOUT time. procrastination but make it a feature ✨
  • topology — topology of the display. the whole layout, the whole aesthetic 🌸
  • idle_timeout — idle timeout duration in milliseconds.
  • wide_bus_en — wide bus is enabled on this interface. wide bus wide vibes 🚌
  • dsc — drm_dsc_config pointer, for DSC-enabled encoders.

🦋 SEE ALSO 🦋

the whole squad, in no particular order (okay it's the original order, don't come for me):

ngl bestie, this page is from the ./drivers/gpu/drm/msm/disp/dpu1 directory, dated October 2026, and it's filed under struct dpu_encoder_virt(9). slay 💅💖 go read the source, it's right there, ily, bye 🫶✨
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