Commit 3db1d524 authored by Erwan Le Ray's avatar Erwan Le Ray Committed by Greg Kroah-Hartman
Browse files

serial: stm32: fix tx_empty condition 



In "tx_empty", we should poll TC bit in both DMA and PIO modes (instead of
TXE) to check transmission data register has been transmitted independently
of the FIFO mode. TC indicates that both transmit register and shift
register are empty. When shift register is empty, tx_empty should return
TIOCSER_TEMT instead of TC value.

Cleans the USART_CR_TC TCCF register define (transmission complete clear
flag) as it is duplicate of USART_ICR_TCCF.

Fixes: 48a6092f ("serial: stm32-usart: Add STM32 USART Driver")
Signed-off-by: default avatarErwan Le Ray <erwan.leray@foss.st.com>
Link: https://lore.kernel.org/r/20210304162308.8984-13-erwan.leray@foss.st.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9f77d192

drivers/tty/serial/stm32-usart.c

+4 −1
Original line number Diff line number Diff line
@@ -515,7 +515,10 @@ static unsigned int stm32_usart_tx_empty(struct uart_port *port) 
	struct stm32_port *stm32_port = to_stm32_port(port);

	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;



	return readl_relaxed(port->membase + ofs->isr) & USART_SR_TXE;

	if (readl_relaxed(port->membase + ofs->isr) & USART_SR_TC)

		return TIOCSER_TEMT;



	return 0;

}



static void stm32_usart_set_mctrl(struct uart_port *port, unsigned int mctrl)

drivers/tty/serial/stm32-usart.h

+0 −3
Original line number Diff line number Diff line
@@ -127,9 +127,6 @@ struct stm32_usart_info stm32h7_info = { 
/* Dummy bits */

#define USART_SR_DUMMY_RX	BIT(16)



/* USART_ICR (F7) */

#define USART_CR_TC		BIT(6)



/* USART_DR */

#define USART_DR_MASK		GENMASK(8, 0)