FROMLIST: serial: qcom_geni: Fix RX DMA stall when SE_DMA_RX_LEN_IN is zero#1264
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mukesh-savaliya merged 1 commit intoJun 1, 2026
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…s zero In qcom_geni_serial_handle_rx_dma(), geni_se_rx_dma_unprep() clears port->rx_dma_addr before SE_DMA_RX_LEN_IN is read. If the register is zero, for example when the RX stale counter fires on an idle line, the handler returns without calling geni_se_rx_dma_prep(). The next RX DMA interrupt then hits the !port->rx_dma_addr guard and returns immediately, so the RX DMA buffer is never rearmed and later input is lost. Keep the handler on the rearm path when rx_in is zero. Warn about the unexpected zero-length DMA completion, skip received-data handling, and always call geni_se_rx_dma_prep(). Link: https://lore.kernel.org/all/20260528-serial-rx-0-byte-fix-v1-1-dc4e876c7368@oss.qualcomm.com/ Fixes: 2aaa43c ("tty: serial: qcom-geni-serial: add support for serial engine DMA") Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
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In qcom_geni_serial_handle_rx_dma(), geni_se_rx_dma_unprep() clears port->rx_dma_addr before SE_DMA_RX_LEN_IN is read. If the register is zero, for example when the RX stale counter fires on an idle line, the handler returns without calling geni_se_rx_dma_prep().
The next RX DMA interrupt then hits the !port->rx_dma_addr guard and returns immediately, so the RX DMA buffer is never rearmed and later input is lost.
Keep the handler on the rearm path when rx_in is zero. Warn about the unexpected zero-length DMA completion, skip received-data handling, and always call geni_se_rx_dma_prep().
Link: https://lore.kernel.org/all/20260528-serial-rx-0-byte-fix-v1-1-dc4e876c7368@oss.qualcomm.com/
Fixes: 2aaa43c ("tty: serial: qcom-geni-serial: add support for serial engine DMA")