mv_check_atapi_dma(9)

okay so bestie 💖 welcome to the mv_check_atapi_dma(9) page from the Kernel API Manual. This is the ATAPI DMA vibe check, and yes, it’s giving “tiny function, very important filter” energy ✨.

🎀 NAME 🎀

mv_check_atapi_dma — filter ATAPI cmds which are unsuitable for DMA. That’s it, that’s the job: it’s the bouncer at the DMA club, checking which ATAPI cmds get in and which ones are a hard no 💅.

✨ SYNOPSIS ✨

int mv_check_atapi_dma (struct ata_queued_cmd *qc );

Returns an int and takes a pointer to struct ata_queued_cmd named qc — short, iconic, no notes 🫶.

🫶 ARGUMENTS 🫶

• qc — the queued command to check for chipset/DMA compatibility. Basically, “does this queued command match the chipset/DMA setup?” energy ✨.

💅 DESCRIPTION 💅

The bmdma engines cannot handle speculative data sizes — that’s the bytecount under/over flow situation 😭 — so this function only allows DMA for data transfer commands with known data sizes. If the data size is not known, it is not getting the DMA pass, periodt.

LOCKING: Inherited from caller. It does not bring its own lock drama; it inherits the locking from whoever called it 🙈.

🌈 SEE ALSO 🌈

Kernel file ./drivers/ata/sata_mv.c and the whole function crew:

• mv_save_cached_regs(9)
• mv_write_cached_reg(9)
• mv_stop_edma_engine(9)
• mv_port_start(9)
• mv_port_stop(9)
• mv_fill_sg(9)
• mv_sff_irq_clear(9)
• mv_bmdma_setup(9)
• mv_bmdma_start(9)
• mv_bmdma_stop_ap(9)
• mv_bmdma_status(9)
• mv_qc_prep(9)
• mv_qc_prep_iie(9)
• mv_sff_check_status(9)
• mv_send_fis(9)
• mv_qc_issue_fis(9)
• mv_qc_issue(9)
• mv_err_intr(9)
• mv_host_intr(9)
• mv_interrupt(9)
• mv_port_init(9)
• mv_init_host(9)
• mv_platform_probe(9)
• mv_print_info(9)
• mv_pci_init_one(9)

Signed off from ./drivers/ata (source/version), dated October 2026 — mv_check_atapi_dma(9) out, bestie 💜✨