Re: [PATCH v4] tty: make pl011 serial port driver support 485 mode
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2021-02-04 15:53:32
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On Mon, Feb 01, 2021 at 03:30:43PM +0800, zhangqiumiao1@huawei.com wrote:
quoted hunk
From: Qiumiao Zhang <redacted> make pl011 serial port support 485 mode full duplex communication Signed-off-by: Qiumiao Zhang <redacted> --- Changes in v4: -Add a bound to the loop in pl011_stop_tx -Remove extra curly braces in pl011_stop_tx Changes in v3: -Fix busy loop forever in pl011_tx_empty -Move the definition of cr into uart_amba_port -Run checkpatch with no error or warning Changes in v2: -Fix two compilation errors drivers/tty/serial/amba-pl011.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+)diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index c255476..026add3 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c@@ -44,6 +44,7 @@ #include "amba-pl011.h" +#define ISEMPTY 1 #define UART_NR 14 #define SERIAL_AMBA_MAJOR 204@@ -264,6 +265,7 @@ struct uart_amba_port { unsigned int fifosize; /* vendor-specific */ unsigned int old_cr; /* state during shutdown */ unsigned int fixed_baud; /* vendor-set fixed baud rate */ + unsigned int cr; char type[12]; #ifdef CONFIG_DMA_ENGINE /* DMA stuff */@@ -1284,14 +1286,33 @@ static inline bool pl011_dma_rx_running(struct uart_amba_port *uap) #define pl011_dma_flush_buffer NULL #endif +static unsigned int pl011_tx_empty(struct uart_port *port); + static void pl011_stop_tx(struct uart_port *port) { + unsigned int count = 1000000; /* 1s */
1 second of what?
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);
uap->im &= ~UART011_TXIM;
pl011_write(uap->im, uap, REG_IMSC);
pl011_dma_tx_stop(uap);
+ if (port->rs485.flags & SER_RS485_ENABLED) {
+ while(pl011_tx_empty(port) != ISEMPTY && count) {
+ count--;
+ cpu_relax();
+ udelay(1);Why relax and delay? And always run checkpatch on your change before sending it out next time. thanks, greg k-h