On Thu, Jun 27, 2019 at 08:16:07AM +0200, Uwe Kleine-König wrote:
> On Wed, Jun 26, 2019 at 12:15:56PM +0200, Sascha Hauer wrote:
> > We have an interrupt for the CTS input (RTS in FSL speech). Its handler
> > calls uart_handle_cts_change(), so we shouldn't do this in
> > imx_uart_mctrl_check() again.
> >
> > Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > ---
> > drivers/tty/serial/imx.c | 6 ------
> > 1 file changed, 6 deletions(-)
> >
> > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> > index a5e80a028e83..0419a084c0ed 100644
> > --- a/drivers/tty/serial/imx.c
> > +++ b/drivers/tty/serial/imx.c
> > @@ -805,12 +805,8 @@ static void imx_uart_clear_rx_errors(struct imx_port *sport);
> > static unsigned int imx_uart_get_hwmctrl(struct imx_port *sport)
> > {
> > unsigned int tmp = TIOCM_DSR;
> > - unsigned usr1 = imx_uart_readl(sport, USR1);
> > unsigned usr2 = imx_uart_readl(sport, USR2);
> >
> > - if (usr1 & USR1_RTSS)
> > - tmp |= TIOCM_CTS;
> > -
> > /* in DCE mode DCDIN is always 0 */
> > if (!(usr2 & USR2_DCDIN))
> > tmp |= TIOCM_CAR;
>
> Is this hunk supposed to be included in this patch? I think it's wrong.
The rationale was that when we do not evaluate the TIOCM_CTS anymore in
the return value of imx_uart_get_hwmctrl() then there's no point in
setting it in the first place. However, imx_uart_get_hwmctrl() also has
another user which needs the flag, so right, this hunk shouldn't be
here.
>
> > @@ -843,8 +839,6 @@ static void imx_uart_mctrl_check(struct imx_port *sport)
> > sport->port.icount.dsr++;
> > if (changed & TIOCM_CAR)
> > uart_handle_dcd_change(&sport->port, status & TIOCM_CAR);
> > - if (changed & TIOCM_CTS)
> > - uart_handle_cts_change(&sport->port, status & TIOCM_CTS);
>
> This doesn't hurt, does it?
With this patch the number of CTS changes is correctly counted, I have
verified this with a logic analyzer. Without it port->icount.cts has 978
changes when it should be only 968 changes.
> Also imx_uart_mctrl_check is called from
> imx_uart_timeout which is supposed to catch missed interrupts and in
> this case uart_handle_cts_change() must be called.
Beginning with 2/2 uart_handle_cts_change() is needed for nothing else
but statistic counting. There won't be any timeout due to missed
interrupts as the hardware handles CTS itself.
Sascha
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