serial: stm32: fix clearing interrupt error flags
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: 4f01d833fd
("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@st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -240,8 +240,8 @@ static void stm32_receive_chars(struct uart_port *port, bool threaded)
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* cleared by the sequence [read SR - read DR].
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* cleared by the sequence [read SR - read DR].
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*/
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*/
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if ((sr & USART_SR_ERR_MASK) && ofs->icr != UNDEF_REG)
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if ((sr & USART_SR_ERR_MASK) && ofs->icr != UNDEF_REG)
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stm32_clr_bits(port, ofs->icr, USART_ICR_ORECF |
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writel_relaxed(sr & USART_SR_ERR_MASK,
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USART_ICR_PECF | USART_ICR_FECF);
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port->membase + ofs->icr);
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c = stm32_get_char(port, &sr, &stm32_port->last_res);
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c = stm32_get_char(port, &sr, &stm32_port->last_res);
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port->icount.rx++;
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port->icount.rx++;
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@ -435,7 +435,7 @@ static void stm32_transmit_chars(struct uart_port *port)
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if (ofs->icr == UNDEF_REG)
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if (ofs->icr == UNDEF_REG)
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stm32_clr_bits(port, ofs->isr, USART_SR_TC);
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stm32_clr_bits(port, ofs->isr, USART_SR_TC);
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else
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else
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stm32_set_bits(port, ofs->icr, USART_ICR_TCCF);
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writel_relaxed(USART_ICR_TCCF, port->membase + ofs->icr);
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if (stm32_port->tx_ch)
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if (stm32_port->tx_ch)
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stm32_transmit_chars_dma(port);
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stm32_transmit_chars_dma(port);
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