sdca_ump_read_message(9)

💅 sdca_ump_read_message — read a UMP message from the device

okay so bestie, this is a page from the Kernel API Manual (section 9, the kernel-functions one, iykyk) and it's literally all about pulling a UMP message out of the device. let's get into it 🎀

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✨ SYNOPSIS ✨

int sdca_ump_read_message (struct device *dev , struct regmap
*device_regmap , struct regmap *function_regmap , struct
sdca_function_data *function , struct sdca_entity *entity , unsigned int
offset_sel , unsigned int length_sel , void **msg );

that's a whole lot of arguments, but don't panic — we're going through every single one of them, no skips 🫶

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🌸 ARGUMENTS 🌸

• dev — pointer to the struct device, and honestly its only job here is to be the thing error messages get reported against. that's it. that's the vibe.
• device_regmap — pointer to the Device register map.
• function_regmap — pointer to the regmap for the SDCA Function.
• function — pointer to the Function information.
• entity — pointer to the SDCA Entity.
• offset_sel — the Control Selector for the UMP Offset Control.
• length_sel — the Control Selector for the UMP Length Control.
• msg — pointer that will be populated with a dynamically buffer containing the UMP message. ⚠️ note that this needs to be freed by the caller — that's on you, bestie, not the kernel. no cap.

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🦋 DESCRIPTION 🦋

okay so here's the correct order of operations, and the way that you must do it, or it's giving chaos:

1. first, the caller should call sdca_ump_get_owner_host to make sure the host currently owns the UMP buffer. vibe check first, always 💅
2. then this function can be used to retrieve a message.
3. it is the caller's responsibility to free the message once it is finished with it. literally don't forget this, I'm begging 😭
4. finally, sdca_ump_set_owner_device should be called to return the buffer to the device. give it back, it's not yours 💖

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👑 RETURN 👑

returns the message length on success, and a negative error code on failure. simple as that, periodt.

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🌈 SEE ALSO 🌈

• Kernel file ./sound/soc/sdca/sdca_ump.c
• sdca_ump_get_owner_host(9)
• sdca_ump_set_owner_device(9)
• sdca_ump_write_message(9)

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and that's the whole page, bestie! it lives at ./sound/soc/sdca and this version is dated October 2026 — iconic, slay, go read the source 💜✨