diff options
| author | Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com> | 2026-05-28 22:48:07 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-06-27 11:07:41 +0100 |
| commit | ead244f937d6ee50600f974b6a3a7374d74784a6 (patch) | |
| tree | a3b495e6cec01eaabe59e20b61e7f631c8a963c2 | |
| parent | 74be188eb2dc1c99d63986167b9a67d415fe7326 (diff) | |
| download | linux-ead244f937d6ee50600f974b6a3a7374d74784a6.tar.gz linux-ead244f937d6ee50600f974b6a3a7374d74784a6.zip | |
serial: qcom_geni: Fix RX DMA stall when SE_DMA_RX_LEN_IN is zero
commit b93062b6d8a1b2d9bad235cac25558a909819026 upstream.
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().
Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA")
Cc: stable@vger.kernel.org
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
Link: https://patch.msgid.link/20260528-serial-rx-0-byte-fix-v2-1-b4195cfe342f@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/serial/qcom_geni_serial.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index 774c0b7f8508..9d372db5216f 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -904,12 +904,9 @@ static void qcom_geni_serial_handle_rx_dma(struct uart_port *uport, bool drop) port->rx_dma_addr = 0; rx_in = readl(uport->membase + SE_DMA_RX_LEN_IN); - if (!rx_in) { - dev_warn(uport->dev, "serial engine reports 0 RX bytes in!\n"); - return; - } - - if (!drop) + if (!rx_in) + dev_warn_ratelimited(uport->dev, "serial engine reports 0 RX bytes in!\n"); + else if (!drop) handle_rx_uart(uport, rx_in); ret = geni_se_rx_dma_prep(&port->se, port->rx_buf, |