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Type:
Bug
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Resolution: Fixed
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Priority:
Medium
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Linux Core SDK
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LCPD-37838
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09.01.00
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11.00
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The dma->rx_running flag in 8250_omap UART driver could be incorrectly set in omap_8250_shutdown().
In omap_8250_shutdown() when UART DMA is enabled, omap_8250_tx_dma_flash() calls __dma_rx_do_complete() to set dma->rx_running = 0.
However, right after it, pm_runtime_get_sync() is called, which could trigger omap8250_runtime_resume() which calls omap_8250_rx_dma() which set dma->rx_running back to 1. This causes the UART port fails to open next time.
Please see the customer report for details.
The following patch could fix the issue:
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index adc85e250822..8ae32c63d5eb 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -731,12 +731,12 @@ static void omap_8250_shutdown(struct uart_port *port) struct uart_8250_port *up = up_to_u8250p(port); struct omap8250_priv *priv = port->private_data; + pm_runtime_get_sync(port->dev); + flush_work(&priv->qos_work); if (up->dma) omap_8250_rx_dma_flush(up); - pm_runtime_get_sync(port->dev); - serial_out(up, UART_OMAP_WER, 0); if (priv->habit & UART_HAS_EFR2) serial_out(up, UART_OMAP_EFR2, 0x0);
fix:
in 11.x: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/?h=ti-linux-6.12.y&id=ac0e4f5f7690088c9ec5e7d822cd0dda12a722a1
