Commit 9d141c1e authored by Udit Kumar's avatar Udit Kumar Committed by Greg Kroah-Hartman
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serial: 8250_omap: Implementation of Errata i2310 

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: b67e830d ("serial: 8250: 8250_omap: Fix possible interrupt storm on K3 SoCs")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarUdit Kumar <u-kumar1@ti.com>
Link: https://lore.kernel.org/r/20240619105903.165434-1-u-kumar1@ti.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0ac18dac

drivers/tty/serial/8250/8250_omap.c

+20 −5
Original line number Diff line number Diff line
@@ -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 +667,24 @@ 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);

		(iir & UART_IIR_RX_TIMEOUT) == UART_IIR_RX_TIMEOUT) {

		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 */