linux-kernel - [RFC PATCH] tty: xilinx_uartps: Fix break detection

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Message-ID: <20240723142858.2905083-1-jminor1@opensource.cirrus.com>
Date: Tue, 23 Jul 2024 14:28:58 +0000
From: James Minor <jminor1@...nsource.cirrus.com>
To: <shubhrajyoti.datta@....com>, <gregkh@...uxfoundation.org>
CC: <patches@...nsource.cirrus.com>, <jirislaby@...nel.org>,
        <michal.simek@....com>, <linux-serial@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        "James Minor" <jminor1@...nsource.cirrus.com>
Subject: [RFC PATCH] tty: xilinx_uartps: Fix break detection

Commit b8a6c3b3d465 ("tty: xilinx_uartps: Fix the ignore_status")
used read_status_mask to mask the isrstatus, even though the
commit appears to be fixing the application of the
ignore_status_mask.  This has a side effect of clearing any
pending CDNS_UART_IXR_FRAMING bit, which in turn means that
cdns_uart_handle_rx break detection will only process framing
errors when parity is enabled (INPCK set via
cdns_uart_set_termios).

Fix this by removing the extra isrstatus masking with
read_status_mask, which still allows the ignore_status_mask to be
applied.

Fixes: b8a6c3b3d465 ("tty: xilinx_uartps: Fix the ignore_status")
Signed-off-by: James Minor <jminor1@...nsource.cirrus.com>
---

The other alternative to this would be a straight revert of
b8a6c3b3d465, since read_status_mask and ignore_status_mask are
both applied in cnds_uart_handle_rx anyway.  Let me know the
preference here and I will change accordingly.

 drivers/tty/serial/xilinx_uartps.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 2acfcea403ce..e9165ae3c2e8 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -485,7 +485,6 @@ static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
 		isrstatus &= ~CDNS_UART_IXR_TXEMPTY;
 	}

-	isrstatus &= port->read_status_mask;
 	isrstatus &= ~port->ignore_status_mask;
 	/*
 	 * Skip RX processing if RX is disabled as RXEMPTY will never be set
-- 
2.34.1