nand_subop_get_data_len(9)

💅 nand_subop_get_data_len — a Kernel API Manual moment ✨

Okay so bestie, real talk: this is a page from the Kernel API Manual, section 9, and the function we're stanning today is nand_subop_get_data_len(9). Buckle up, it's giving NAND flash realness 🦋

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🌸 NAME 🌸

nand_subop_get_data_len — get the number of bytes to retrieve 🔥

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✨ SYNOPSIS ✨

unsigned int nand_subop_get_data_len (const struct nand_subop *subop ,
unsigned int instr_idx );

That's the whole vibe. Two args, one unsigned int back. Slay 💖

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🎀 ARGUMENTS 🎀

• subop — the entire sub-operation, like the whole group chat, not just one message 🫶
• instr_idx — index of the instruction inside that sub-operation. iykyk, it's the message you're actually replying to ✨

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💜 DESCRIPTION 💜

So during driver development, you might be tempted — so tempted — to just reach straight into the ->data->len field of a data instruction. Bestie. No. That's wrong, and here's the tea: data instructions might be split 😭

This function returns the length of the chunk of data to send/receive. That's it. That's the whole function. And honestly? Iconic 👑

not me warning you about ->data->len twice — pls don't do it, it's literally right there in the manpage and I will know 🙈

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🦋 SEE ALSO 🦋

Okay this list is long — like, main character energy long — but every single one of these is a real reference and you're gonna read them all, periodt. Kernel file ./drivers/mtd/nand/raw/nand_base.c and then:

nand_extract_bits(9), nand_select_target(9), nand_deselect_target(9), nand_release_device(9), nand_bbm_get_next_page(9), nand_block_bad(9), nand_region_is_secured(9), nand_get_device(9), nand_check_wp(9), nand_fill_oob(9), nand_do_write_oob(9), nand_default_block_markbad(9), nand_markbad_bbm(9), nand_block_markbad_lowlevel(9), nand_block_isreserved(9), nand_block_checkbad(9), nand_soft_waitrdy(9), nand_gpio_waitrdy(9), panic_nand_wait(9), nand_reset_interface(9), nand_setup_interface(9), nand_choose_best_sdr_timings(9), nand_choose_best_nvddr_timings(9), nand_choose_best_timings(9), nand_choose_interface_config(9), nand_fill_column_cycles(9), nand_read_page_op(9), nand_read_param_page_op(9), nand_change_read_column_op(9), nand_read_oob_op(9), nand_prog_page_begin_op(9), nand_prog_page_end_op(9), nand_prog_page_op(9), nand_change_write_column_op(9), nand_readid_op(9), nand_status_op(9), nand_exit_status_op(9), nand_erase_op(9), nand_set_features_op(9), nand_get_features_op(9), nand_reset_op(9), nand_read_data_op(9), nand_write_data_op(9), struct nand_op_parser_ctx(9), nand_op_parser_must_split_instr(9), nand_op_parser_match_pat(9), nand_op_parser_exec_op(9), nand_subop_get_addr_start_off(9), nand_subop_get_num_addr_cyc(9), nand_subop_get_data_start_off(9), nand_reset(9), nand_get_features(9), nand_set_features(9), nand_read_page_raw_notsupp(9), nand_read_page_raw(9), nand_monolithic_read_page_raw(9), nand_read_page_raw_syndrome(9), nand_read_page_swecc(9), nand_read_subpage(9), nand_read_page_hwecc(9), nand_read_page_hwecc_oob_first(9), nand_read_page_syndrome(9), nand_transfer_oob(9), nand_setup_read_retry(9), nand_do_read_ops(9), nand_read_oob_std(9), nand_read_oob_syndrome(9), nand_write_oob_std(9), nand_write_oob_syndrome(9), nand_do_read_oob(9), nand_read_oob(9), nand_write_page_raw_notsupp(9), nand_write_page_raw(9), nand_monolithic_write_page_raw(9), nand_write_page_raw_syndrome(9), nand_write_page_swecc(9), nand_write_page_hwecc(9), nand_write_subpage_hwecc(9), nand_write_page_syndrome(9), nand_write_page(9), nand_do_write_ops(9), panic_nand_write(9), nand_write_oob(9), nand_erase(9), nand_erase_nand(9), nand_sync(9), nand_block_isbad(9), nand_block_markbad(9), nand_suspend(9), nand_resume(9), nand_shutdown(9), nand_lock(9), nand_unlock(9), rawnand_dt_parse_gpio_cs(9), nand_scan_ident(9), nand_check_ecc_caps(9), nand_match_ecc_req(9), nand_maximize_ecc(9), nand_ecc_choose_conf(9), nand_scan_tail(9), nand_scan_with_ids(9), nand_cleanup(9)

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and that's the whole page, bestie — go read some NAND source, you got this 🧚💫

Also lowkey for the record: this page lives in ./drivers/mtd/nand/raw, out here representing the Kernel API Manual, and it's dated October 2026. Signed, sealed, timestamped 🎀💖