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X-OriginatorOrg: ti.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Jan 2026 08:18:41.6010 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b412f48b-6e1b-4b88-7332-08de51b3323f X-MS-Exchange-CrossTenant-Id: e5b49634-450b-4709-8abb-1e2b19b982b7 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=e5b49634-450b-4709-8abb-1e2b19b982b7;Ip=[198.47.21.195];Helo=[flwvzet201.ext.ti.com] X-MS-Exchange-CrossTenant-AuthSource: MN1PEPF0000F0DF.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR10MB997765 Content-Type: text/plain; charset="utf-8" The DMA IRQ handler does not accounts for the overrun(OE) or any other errors being reported by the IP before triggering a DMA transaction which leads to the interrupts not being handled resulting into an IRQ storm. The way to handle OE is to: 1. Reset the RX FIFO. 2. Read the UART_RESUME register, which clears the internal flag Earlier, the driver issued DMA transations even in case of OE which shouldn= 't be done according to the OE handling mechanism mentioned above, as we are resetting the FIFO's, refer section: "12.1.6.4.8.1.3.6 Overrun During Receive" [0]. [0] https://www.ti.com/lit/pdf/spruiu1 Signed-off-by: Moteen Shah --- drivers/tty/serial/8250/8250_omap.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/= 8250_omap.c index 9e49ef48b851..e26bae0a6488 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -100,6 +100,9 @@ #define OMAP_UART_REV_52 0x0502 #define OMAP_UART_REV_63 0x0603 =20 +/* Resume register */ +#define UART_OMAP_RESUME 0x0B + /* Interrupt Enable Register 2 */ #define UART_OMAP_IER2 0x1B #define UART_OMAP_IER2_RHR_IT_DIS BIT(2) @@ -119,7 +122,6 @@ /* Timeout low and High */ #define UART_OMAP_TO_L 0x26 #define UART_OMAP_TO_H 0x27 - struct omap8250_priv { void __iomem *membase; int line; @@ -1256,6 +1258,20 @@ static u16 omap_8250_handle_rx_dma(struct uart_8250_= port *up, u8 iir, u16 status return status; } =20 +static void am654_8250_handle_uart_errors(struct uart_8250_port *up, u8 ii= r, u16 status) +{ + if (status & UART_LSR_OE) { + serial8250_clear_and_reinit_fifos(up); + serial_in(up, UART_LSR); + serial_in(up, UART_OMAP_RESUME); + } else { + if (status & (UART_LSR_FE | UART_LSR_PE | UART_LSR_BI)) + serial_in(up, UART_RX); + if (iir & UART_IIR_XOFF) + serial_in(up, UART_IIR); + } +} + static void am654_8250_handle_rx_dma(struct uart_8250_port *up, u8 iir, u16 status) { @@ -1266,7 +1282,8 @@ static void am654_8250_handle_rx_dma(struct uart_8250= _port *up, u8 iir, * Queue a new transfer if FIFO has data. */ if ((status & (UART_LSR_DR | UART_LSR_BI)) && - (up->ier & UART_IER_RDI)) { + (up->ier & UART_IER_RDI) && !(status & UART_LSR_OE)) { + am654_8250_handle_uart_errors(up, iir, status); omap_8250_rx_dma(up); serial_out(up, UART_OMAP_EFR2, UART_OMAP_EFR2_TIMEOUT_BEHAVE); } else if ((iir & 0x3f) =3D=3D UART_IIR_RX_TIMEOUT) { @@ -1282,6 +1299,8 @@ static void am654_8250_handle_rx_dma(struct uart_8250= _port *up, u8 iir, serial_out(up, UART_OMAP_EFR2, 0x0); up->ier |=3D UART_IER_RLSI | UART_IER_RDI; serial_out(up, UART_IER, up->ier); + } else { + am654_8250_handle_uart_errors(up, iir, status); 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X-OriginatorOrg: ti.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Jan 2026 08:18:43.3677 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 710629d5-a51b-44d6-87bb-08de51b3334d X-MS-Exchange-CrossTenant-Id: e5b49634-450b-4709-8abb-1e2b19b982b7 X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=e5b49634-450b-4709-8abb-1e2b19b982b7;Ip=[198.47.23.194];Helo=[lewvzet200.ext.ti.com] X-MS-Exchange-CrossTenant-AuthSource: BL02EPF0001A0FA.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV3PR10MB7817 Content-Type: text/plain; charset="utf-8" Clear rx_running flag only after DMA teardown polling completes. In the previous implementation the flag was being cleared while hardware teardown was still in progress, creating a mismatch between software state (flag =3D 0, "ready") and hardware state (still terminating). Signed-off-by: Moteen Shah --- drivers/tty/serial/8250/8250_omap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/= 8250_omap.c index e26bae0a6488..272bc07c9a6b 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -931,7 +931,6 @@ static void __dma_rx_do_complete(struct uart_8250_port = *p) goto out; =20 cookie =3D dma->rx_cookie; - dma->rx_running =3D 0; =20 /* Re-enable RX FIFO interrupt now that transfer is complete */ if (priv->habit & UART_HAS_RHR_IT_DIS) { @@ -965,6 +964,7 @@ static void __dma_rx_do_complete(struct uart_8250_port = *p) goto out; ret =3D tty_insert_flip_string(tty_port, dma->rx_buf, count); =20 + dma->rx_running =3D 0; p->port.icount.rx +=3D ret; p->port.icount.buf_overrun +=3D count - ret; out: --=20 2.34.1