提交 a931237c 编写于 作者: I Ilpo Järvinen 提交者: Greg Kroah-Hartman

serial: 8250: Fall back to non-DMA Rx if IIR_RDI occurs

DW UART sometimes triggers IIR_RDI during DMA Rx when IIR_RX_TIMEOUT
should have been triggered instead. Since IIR_RDI has higher priority
than IIR_RX_TIMEOUT, this causes the Rx to hang into interrupt loop.
The problem seems to occur at least with some combinations of
small-sized transfers (I've reproduced the problem on Elkhart Lake PSE
UARTs).

If there's already an on-going Rx DMA and IIR_RDI triggers, fall
graciously back to non-DMA Rx. That is, behave as if IIR_RX_TIMEOUT had
occurred.

8250_omap already considers IIR_RDI similar to this change so its
nothing unheard of.

Fixes: 75df022b ("serial: 8250_dma: Fix RX handling")
Cc: <stable@vger.kernel.org>
Co-developed-by: NSrikanth Thokala <srikanth.thokala@intel.com>
Signed-off-by: NSrikanth Thokala <srikanth.thokala@intel.com>
Co-developed-by: NAman Kumar <aman.kumar@intel.com>
Signed-off-by: NAman Kumar <aman.kumar@intel.com>
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221108121952.5497-2-ilpo.jarvinen@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
上级 7b7dfe48
......@@ -1897,6 +1897,10 @@ EXPORT_SYMBOL_GPL(serial8250_modem_status);
static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
{
switch (iir & 0x3f) {
case UART_IIR_RDI:
if (!up->dma->rx_running)
break;
fallthrough;
case UART_IIR_RX_TIMEOUT:
serial8250_rx_dma_flush(up);
fallthrough;
......
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