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From: Fabrice Gasnier <fabrice.gasnier@st.com>
To: <gregkh@linuxfoundation.org>
Cc: <jslaby@suse.com>, <mcoquelin.stm32@gmail.com>,
	<alexandre.torgue@st.com>, <erwan.leray@st.com>,
	<linux-serial@vger.kernel.org>,
	<linux-stm32@st-md-mailman.stormreply.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>
Subject: [PATCH] serial: stm32: fix clearing interrupt error flags
Date: Thu, 21 Nov 2019 09:10:49 +0100	[thread overview]
Message-ID: <1574323849-1909-1-git-send-email-fabrice.gasnier@st.com> (raw)

The interrupt clear flag register is a "write 1 to clear" register.
So, only writing ones allows to clear flags:
- Replace buggy stm32_clr_bits() by a simple write to clear error flags
- Replace useless read/modify/write stm32_set_bits() routine by a
  simple write to clear TC (transfer complete) flag.

Fixes: 4f01d833fdcd ("serial: stm32: fix rx error handling")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/tty/serial/stm32-usart.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index df90747..2f72514 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -240,8 +240,8 @@ static void stm32_receive_chars(struct uart_port *port, bool threaded)
 		 * cleared by the sequence [read SR - read DR].
 		 */
 		if ((sr & USART_SR_ERR_MASK) && ofs->icr != UNDEF_REG)
-			stm32_clr_bits(port, ofs->icr, USART_ICR_ORECF |
-				       USART_ICR_PECF | USART_ICR_FECF);
+			writel_relaxed(sr & USART_SR_ERR_MASK,
+				       port->membase + ofs->icr);
 
 		c = stm32_get_char(port, &sr, &stm32_port->last_res);
 		port->icount.rx++;
@@ -435,7 +435,7 @@ static void stm32_transmit_chars(struct uart_port *port)
 	if (ofs->icr == UNDEF_REG)
 		stm32_clr_bits(port, ofs->isr, USART_SR_TC);
 	else
-		stm32_set_bits(port, ofs->icr, USART_ICR_TCCF);
+		writel_relaxed(USART_ICR_TCCF, port->membase + ofs->icr);
 
 	if (stm32_port->tx_ch)
 		stm32_transmit_chars_dma(port);
-- 
2.7.4


WARNING: multiple messages have this Message-ID (diff)
From: Fabrice Gasnier <fabrice.gasnier@st.com>
To: <gregkh@linuxfoundation.org>
Cc: mcoquelin.stm32@gmail.com, alexandre.torgue@st.com,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-serial@vger.kernel.org, jslaby@suse.com,
	linux-stm32@st-md-mailman.stormreply.com, erwan.leray@st.com
Subject: [PATCH] serial: stm32: fix clearing interrupt error flags
Date: Thu, 21 Nov 2019 09:10:49 +0100	[thread overview]
Message-ID: <1574323849-1909-1-git-send-email-fabrice.gasnier@st.com> (raw)

The interrupt clear flag register is a "write 1 to clear" register.
So, only writing ones allows to clear flags:
- Replace buggy stm32_clr_bits() by a simple write to clear error flags
- Replace useless read/modify/write stm32_set_bits() routine by a
  simple write to clear TC (transfer complete) flag.

Fixes: 4f01d833fdcd ("serial: stm32: fix rx error handling")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/tty/serial/stm32-usart.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index df90747..2f72514 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -240,8 +240,8 @@ static void stm32_receive_chars(struct uart_port *port, bool threaded)
 		 * cleared by the sequence [read SR - read DR].
 		 */
 		if ((sr & USART_SR_ERR_MASK) && ofs->icr != UNDEF_REG)
-			stm32_clr_bits(port, ofs->icr, USART_ICR_ORECF |
-				       USART_ICR_PECF | USART_ICR_FECF);
+			writel_relaxed(sr & USART_SR_ERR_MASK,
+				       port->membase + ofs->icr);
 
 		c = stm32_get_char(port, &sr, &stm32_port->last_res);
 		port->icount.rx++;
@@ -435,7 +435,7 @@ static void stm32_transmit_chars(struct uart_port *port)
 	if (ofs->icr == UNDEF_REG)
 		stm32_clr_bits(port, ofs->isr, USART_SR_TC);
 	else
-		stm32_set_bits(port, ofs->icr, USART_ICR_TCCF);
+		writel_relaxed(USART_ICR_TCCF, port->membase + ofs->icr);
 
 	if (stm32_port->tx_ch)
 		stm32_transmit_chars_dma(port);
-- 
2.7.4


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             reply	other threads:[~2019-11-21  8:12 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-21  8:10 Fabrice Gasnier [this message]
2019-11-21  8:10 ` [PATCH] serial: stm32: fix clearing interrupt error flags Fabrice Gasnier

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