drm_dp_dpcd_read_data(9)

💅 drm_dp_dpcd_read_data(9) — Kernel API Manual, but make it cute

okay so this is drm_dp_dpcd_read_data from the Kernel API Manual, and honestly? she's a little workhorse and she deserves her flowers 💐

---

✨ NAME ✨

drm_dp_dpcd_read_data — read a whole series of bytes out of the DPCD, bestie. that's the whole vibe. 📖✨

---

🦋 SYNOPSIS 🦋

int drm_dp_dpcd_read_data (struct drm_dp_aux *aux , unsigned int offset
, void *buffer , size_t size );

like, that's the signature, don't @ me, just copy it exactly fr fr 🫶

---

🎀 ARGUMENTS 🎀

• aux — the DisplayPort AUX channel, and yes she can be SST or MST, both are welcome here, no gatekeeping 💅
• offset — the address of the (first) register you wanna read. first one! because she reads a bunch from there onward 📍
• buffer — the buffer where the register values get stashed. it's giving "here's where the lore goes" 🧺
• size — how many bytes are in buffer. the headcount. the guest list. 🔢

---

🌸 DESCRIPTION 🌸

so here's the tea ☕ — she returns zero (0) on success, or a negative error code if something went sideways. that's the whole contract, no cap.

• -EIO — returned if the request got NAKed by the sink, or if the retry count was exceeded. like, the sink literally said "no ❌" or you ran out of tries 😭
• -EPROTO — returned if not all the bytes got transferred. partial delivery is not the vibe, she wants the full package 💀

and errors coming from the underlying AUX channel transfer function get propagated straight to the caller — except -EBUSY, which causes the transaction to be retried. she's persistent, she's patient, she's iconic 👑

heads up: those error codes are legit return values, not decoration. check them. i'm not playing 🙈

---

🌈 SEE ALSO 🌈

the whole friend group 🫂 — go say hi:

• Kernel file ./include/drm/display/drm_dp_helper.h
• struct drm_dp_vsc_sdp(9)
• struct drm_dp_as_sdp(9)
• drm_dp_dsc_sink_supports_format(9)
• drm_edp_backlight_supported(9)
• drm_dp_is_uhbr_rate(9)
• struct drm_dp_aux_msg(9)
• struct drm_dp_aux_cec(9)
• struct drm_dp_aux(9)
• drm_dp_dpcd_readb(9)
• drm_dp_dpcd_write_data(9)
• drm_dp_dpcd_writeb(9)
• drm_dp_dpcd_read_byte(9)
• drm_dp_dpcd_write_byte(9)
• struct drm_dp_desc(9)
• enum drm_dp_quirk(9)
• drm_dp_has_quirk(9)
• struct drm_edp_backlight_info(9)
• struct drm_dp_phy_test_params(9)

---

and that's the page, bestie 💜 huge shoutout to ./include/drm/display for hosting this one, dated October 2026, from the Kernel API Manual — mwah, go read your DPCD responsibly 🧚‍♀️✨