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Commit c3a16e7c authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by Greg Kroah-Hartman
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serial: stm32-usart: Correct CSIZE, bits, and parity 



[ Upstream commit 1deeda8d2877c18bc2b9eeee10dd6d2628852848 ]

Add CSIZE sanitization for unsupported CSIZE configurations. In
addition, if parity is asked for but CSx was unsupported, the sensible
result is CS8+parity which requires setting USART_CR1_M0 like with 9
bits.

Incorrect CSIZE results in miscalculation of the frame bits in
tty_get_char_size() or in its predecessor where the roughly the same
code is directly within uart_update_timeout().

Fixes: c8a9d043 (serial: stm32: fix word length configuration)
Cc: Erwan Le Ray <erwan.leray@st.com>
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220519081808.3776-9-ilpo.jarvinen@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 29d96363

drivers/tty/serial/stm32-usart.c

+12 −3
Original line number Original line Diff line number Diff line
@@ -745,13 +745,22 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios, 
	 * CS8 or (CS7 + parity), 8 bits word aka [M1:M0] = 0b00

	 * CS8 or (CS7 + parity), 8 bits word aka [M1:M0] = 0b00

	 * M0 and M1 already cleared by cr1 initialization.

	 * M0 and M1 already cleared by cr1 initialization.

	 */

	 */

	if (bits == 9)

	if (bits == 9) {

		cr1 |= USART_CR1_M0;

		cr1 |= USART_CR1_M0;

	else if ((bits == 7) && cfg->has_7bits_data)

	} else if ((bits == 7) && cfg->has_7bits_data) {

		cr1 |= USART_CR1_M1;

		cr1 |= USART_CR1_M1;

	else if (bits != 8)

	} else if (bits != 8) {

		dev_dbg(port->dev, "Unsupported data bits config: %u bits\n"

		dev_dbg(port->dev, "Unsupported data bits config: %u bits\n"

			, bits);

			, bits);

		cflag &= ~CSIZE;

		cflag |= CS8;

		termios->c_cflag = cflag;

		bits = 8;

		if (cflag & PARENB) {

			bits++;

			cr1 |= USART_CR1_M0;

		}

	}





	if (ofs->rtor != UNDEF_REG && (stm32_port->rx_ch ||

	if (ofs->rtor != UNDEF_REG && (stm32_port->rx_ch ||

				       stm32_port->fifoen)) {

				       stm32_port->fifoen)) {