From: Fabrice Gasnier fabrice.gasnier@st.com
commit 1250ed7114a977cdc2a67a0c09d6cdda63970eb9 upstream.
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 Cc: stable stable@vger.kernel.org Link: https://lore.kernel.org/r/1574323849-1909-1-git-send-email-fabrice.gasnier@s... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/serial/stm32-usart.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -239,8 +239,8 @@ static void stm32_receive_chars(struct u * 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++; @@ -434,7 +434,7 @@ static void stm32_transmit_chars(struct 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);