On Fri, Jan 15, 2021 at 02:32:39AM +0000, zhangqiumiao wrote:
> On Thu, Jan 14, 2021 at 08:28:30PM +0800, zhangqiumiao1@xxxxxxxxxx wrote:
> > From: Qiumiao Zhang <zhangqiumiao1@xxxxxxxxxx>
> >
> > make pl011 serial port support 485 mode full duplex communication
> >
> > Signed-off-by: Qiumiao Zhang <zhangqiumiao1@xxxxxxxxxx>
> > ---
> > 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 | 32 ++++++++++++++++++++++++++++++++
> > 1 file changed, 32 insertions(+)
> >
> > diff --git a/drivers/tty/serial/amba-pl011.c
> > b/drivers/tty/serial/amba-pl011.c index c255476..9da10a4 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 */
> > @@ -1284,6 +1286,8 @@ 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) {
> > struct uart_amba_port *uap =
> > @@ -1292,6 +1296,17 @@ static void pl011_stop_tx(struct uart_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) ;
>
> I intend to change this to:
> while(pl011_tx_empty(port) != ISEMPTY)
> cpu_relax();
> Is this ok?
See other comments on this same list (linux-serial) for a patch for a
different driver a few days ago about why doing that would not be a good
idea. Did you not review that change when it was submitted?
> > +
> > + uap->cr = pl011_read(uap, REG_CR);
> > + if (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) {
> > + uap->cr |= UART011_CR_RTS;
> > + } else {
> > + uap->cr &= ~UART011_CR_RTS;
> > + }
>
> Checkpatch doesn't find the problem here. Please tell me what's wrong here?
No braces should be needed, have you read the coding style rules?
thanks,
greg k-h
