| Message ID | 20230804140904.176552-1-patrice.chotard@foss.st.com |
|---|---|
| State | Accepted |
| Commit | 9e8cbea1a74516235820ccd50d513c961e43cb70 |
| Delegated to: | Patrice Chotard |
| Headers | show |
| Series | serial: stm32: extend TC timeout | expand |
On 8/4/23 16:09, Patrice Chotard wrote: > From: Valentin Caron <valentin.caron@foss.st.com> > > Waiting 150us TC bit couldn't be enough. > > If TFA lets 16 bits in USART fifo, we has to wait 16 times 87 us (time > of 10 bits (1 byte in most use cases) at a baud rate of 115200). > > Fixes: b4dbc5d65a67 ("serial: stm32: Wait TC bit before performing initialization") > > Signed-off-by: Valentin Caron <valentin.caron@foss.st.com> > Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com> > --- > > drivers/serial/serial_stm32.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/drivers/serial/serial_stm32.c b/drivers/serial/serial_stm32.c > index 0085113f674..23d476fba28 100644 > --- a/drivers/serial/serial_stm32.c > +++ b/drivers/serial/serial_stm32.c > @@ -22,6 +22,14 @@ > #include "serial_stm32.h" > #include <dm/device_compat.h> > > +/* > + * At 115200 bits/s > + * 1 bit = 1 / 115200 = 8,68 us > + * 8 bits = 69,444 us > + * 10 bits are needed for worst case (8 bits + 1 start + 1 stop) = 86.806 us > + */ > +#define ONE_BYTE_B115200_US 87 > + > static void _stm32_serial_setbrg(fdt_addr_t base, > struct stm32_uart_info *uart_info, > u32 clock_rate, > @@ -209,12 +217,10 @@ static int stm32_serial_probe(struct udevice *dev) > * before uart initialization, wait for TC bit (Transmission Complete) > * in case there is still chars from previous bootstage to transmit > */ > - ret = read_poll_timeout(readl, isr, isr & USART_ISR_TC, 10, 150, > - plat->base + ISR_OFFSET(stm32f4)); > - if (ret) { > - clk_disable(&clk); > - return ret; > - } > + ret = read_poll_timeout(readl, isr, isr & USART_ISR_TC, 50, > + 16 * ONE_BYTE_B115200_US, plat->base + ISR_OFFSET(stm32f4)); > + if (ret) > + dev_dbg(dev, "FIFO not empty, some character can be lost (%d)\n", ret); > > ret = reset_get_by_index(dev, 0, &reset); > if (!ret) { Applied on stm32-master
diff --git a/drivers/serial/serial_stm32.c b/drivers/serial/serial_stm32.c index 0085113f674..23d476fba28 100644 --- a/drivers/serial/serial_stm32.c +++ b/drivers/serial/serial_stm32.c @@ -22,6 +22,14 @@ #include "serial_stm32.h" #include <dm/device_compat.h> +/* + * At 115200 bits/s + * 1 bit = 1 / 115200 = 8,68 us + * 8 bits = 69,444 us + * 10 bits are needed for worst case (8 bits + 1 start + 1 stop) = 86.806 us + */ +#define ONE_BYTE_B115200_US 87 + static void _stm32_serial_setbrg(fdt_addr_t base, struct stm32_uart_info *uart_info, u32 clock_rate, @@ -209,12 +217,10 @@ static int stm32_serial_probe(struct udevice *dev) * before uart initialization, wait for TC bit (Transmission Complete) * in case there is still chars from previous bootstage to transmit */ - ret = read_poll_timeout(readl, isr, isr & USART_ISR_TC, 10, 150, - plat->base + ISR_OFFSET(stm32f4)); - if (ret) { - clk_disable(&clk); - return ret; - } + ret = read_poll_timeout(readl, isr, isr & USART_ISR_TC, 50, + 16 * ONE_BYTE_B115200_US, plat->base + ISR_OFFSET(stm32f4)); + if (ret) + dev_dbg(dev, "FIFO not empty, some character can be lost (%d)\n", ret); ret = reset_get_by_index(dev, 0, &reset); if (!ret) {