From: Erwan Le Ray erwan.leray@foss.st.com
[ Upstream commit 3db1d52466dc11dca4e47ef12a6e6e97f846af62 ]
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: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") Signed-off-by: Erwan Le Ray erwan.leray@foss.st.com Link: https://lore.kernel.org/r/20210304162308.8984-13-erwan.leray@foss.st.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/stm32-usart.c | 5 ++++- drivers/tty/serial/stm32-usart.h | 3 --- 2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 6756f73fb220..23b7bdae173c 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -502,7 +502,10 @@ static unsigned int stm32_tx_empty(struct uart_port *port) struct stm32_port *stm32_port = to_stm32_port(port); 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_set_mctrl(struct uart_port *port, unsigned int mctrl) diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h index a175c1094dc8..a0b816e0e89b 100644 --- a/drivers/tty/serial/stm32-usart.h +++ b/drivers/tty/serial/stm32-usart.h @@ -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)