bcm2835_wait_tx_fifo_empty(9)

🎀 bcm2835_wait_tx_fifo_empty(9) 🎀

okay so bestie, this is from the Kernel API Manual, and we're talking about bcm2835_wait_tx_fifo_empty — yes, the whole name, slay. It's giving “tiny function, very real consequences,” so let's get into it. 💅

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✨ NAME ✨

bcm2835_wait_tx_fifo_empty — busy-wait for TX FIFO to empty. periodt. 💖

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🌸 SYNOPSIS 🌸

void bcm2835_wait_tx_fifo_empty (struct bcm2835_spi *bs );

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🦋 ARGUMENTS 🦋

• bs — the BCM2835 SPI controller. that's the one, bestie. 🫶

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🔥 DESCRIPTION 🔥

okay so real talk: the caller must ensure that the RX FIFO can accommodate as many bytes as have been written to the TX FIFO. no cap, this is not optional. 😭

Transmission is halted once the RX FIFO is full, and that causes this function to spin forever. like, literally forever. 💀

⚠️ so if you set this up wrong, bcm2835_wait_tx_fifo_empty is not gonna rescue you — it's gonna spin. forever. bestie, please check your FIFO situation first. 🙈

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👑 SEE ALSO 👑

go read these next, iykyk 🫶:

• Kernel file ./drivers/spi/spi-bcm2835.c
• struct bcm2835_spi(9)
• struct bcm2835_spidev(9)
• bcm2835_rd_fifo_count(9)
• bcm2835_wr_fifo_count(9)
• bcm2835_rd_fifo_blind(9)
• bcm2835_wr_fifo_blind(9)
• bcm2835_spi_transfer_prologue(9)
• bcm2835_spi_undo_prologue(9)
• bcm2835_spi_dma_rx_done(9)
• bcm2835_spi_dma_tx_done(9)
• bcm2835_spi_prepare_sg(9)
• bcm2835_spi_transfer_one_dma(9)

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mwah 💋 — signed off from ./drivers/spi, October 2026, still living in the Kernel API Manual. 💖