As per Errata i2310[0], Erroneous timeout can be triggered, if this Erroneous interrupt is not cleared then it may leads to storm of interrupts, therefore apply Errata i2310 solution.

[0] https://www.ti.com/lit/pdf/sprz536 page 23

Fixes: b67e830d38fa ("serial: 8250: 8250_omap: Fix possible interrupt storm on K3 SoCs") Cc: stable@vger.kernel.org Signed-off-by: Udit Kumar u-kumar1@ti.com --- Test logs: https://gist.github.com/uditkumarti/48e239540db4e761861fbd1d7d31cfed

Change logs Changes in v4: - Reverted fifo empty check before applying errata Link to v3: https://lore.kernel.org/all/20240619105903.165434-1-u-kumar1@ti.com/

Changes in v3: - CC stable in commit message Link to v2: https://lore.kernel.org/all/20240617052253.2188140-1-u-kumar1@ti.com/

Changes in v2: - Added Fixes Tag and typo correction in commit message - Corrected bit position to UART_OMAP_EFR2_TIMEOUT_BEHAVE Link to v1 https://lore.kernel.org/all/20240614061314.290840-1-u-kumar1@ti.com/

drivers/tty/serial/8250/8250_omap.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 170639d12b2a..1af9aed99c65 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -115,6 +115,10 @@ /* RX FIFO occupancy indicator */ #define UART_OMAP_RX_LVL 0x19

+/* Timeout low and High */ +#define UART_OMAP_TO_L 0x26 +#define UART_OMAP_TO_H 0x27 + /* * Copy of the genpd flags for the console. * Only used if console suspend is disabled @@ -663,13 +667,25 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id)

/* * On K3 SoCs, it is observed that RX TIMEOUT is signalled after - * FIFO has been drained, in which case a dummy read of RX FIFO - * is required to clear RX TIMEOUT condition. + * FIFO has been drained or erroneously. + * So apply solution of Errata i2310 as mentioned in + * https://www.ti.com/lit/pdf/sprz536 */ if (priv->habit & UART_RX_TIMEOUT_QUIRK && (iir & UART_IIR_RX_TIMEOUT) == UART_IIR_RX_TIMEOUT && serial_port_in(port, UART_OMAP_RX_LVL) == 0) { - serial_port_in(port, UART_RX); + unsigned char efr2, timeout_h, timeout_l; + + efr2 = serial_in(up, UART_OMAP_EFR2); + timeout_h = serial_in(up, UART_OMAP_TO_H); + timeout_l = serial_in(up, UART_OMAP_TO_L); + serial_out(up, UART_OMAP_TO_H, 0xFF); + serial_out(up, UART_OMAP_TO_L, 0xFF); + serial_out(up, UART_OMAP_EFR2, UART_OMAP_EFR2_TIMEOUT_BEHAVE); + serial_in(up, UART_IIR); + serial_out(up, UART_OMAP_EFR2, efr2); + serial_out(up, UART_OMAP_TO_H, timeout_h); + serial_out(up, UART_OMAP_TO_L, timeout_l); }

/* Stop processing interrupts on input overrun */