From cfb16f595faefc5245c8f4adc067ae1562b5d444 Mon Sep 17 00:00:00 2001
From: Udit Kumar <u-kumar1@ti.com>
Date: Tue, 25 Jun 2024 21:37:25 +0530
Subject: [PATCH] serial: 8250_omap: Fix Errata i2310 with RX FIFO level check
commit c128a1b0523b685c8856ddc0ac0e1caef1fdeee5 upstream.
Errata i2310[0] says, Erroneous timeout can be triggered,
if this Erroneous interrupt is not cleared then it may leads
to storm of interrupts.
Commit 9d141c1e6157 ("serial: 8250_omap: Implementation of Errata i2310")
which added the workaround but missed ensuring RX FIFO is really empty
before applying the errata workaround as recommended in the errata text.
Fix this by adding back check for UART_OMAP_RX_LVL to be 0 for
workaround to take effect.
[0] https://www.ti.com/lit/pdf/sprz536 page 23
Fixes: 9d141c1e6157 ("serial: 8250_omap: Implementation of Errata i2310")
Cc: stable@vger.kernel.org
Reported-by: Vignesh Raghavendra <vigneshr@ti.com>
Closes: https://lore.kernel.org/all/e96d0c55-0b12-4cbf-9d23-48963543de49@ti.com/
Signed-off-by: Udit Kumar <u-kumar1@ti.com>
Link: https://lore.kernel.org/r/20240625160725.2102194-1-u-kumar1@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/8250/8250_omap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 48dad64389d74..a3eaf293f2048 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -637,7 +637,8 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id)
* https://www.ti.com/lit/pdf/sprz536
*/
if (priv->habit & UART_RX_TIMEOUT_QUIRK &&
- (iir & UART_IIR_RX_TIMEOUT) == UART_IIR_RX_TIMEOUT) {
+ (iir & UART_IIR_RX_TIMEOUT) == UART_IIR_RX_TIMEOUT &&
+ serial_port_in(port, UART_OMAP_RX_LVL) == 0) {
unsigned char efr2, timeout_h, timeout_l;
efr2 = serial_in(up, UART_OMAP_EFR2);
--
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