Re: [STLinux Kernel] [PATCH 3/8] serial: st-asc: Read in all Pinctrl states

Lee Jones
2017-01-27T11:54:58Z

On Wed, 25 Jan 2017, Peter Griffin wrote:

> Hi Lee,
>
> On Tue, 24 Jan 2017, Lee Jones wrote:
>
> > There are now 2 possible separate/different Pinctrl states which can
> > be provided from platform data. One which encompasses the lines
> > required for HW flow-control (CTS/RTS) and another which does not
> > specify these lines, such that they can be used via GPIO mechanisms
> > for manually toggling (i.e. from a request by `stty`).
> >
> > Signed-off-by: Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> > ---
> > drivers/tty/serial/st-asc.c | 28 ++++++++++++++++++++++++++++
> > 1 file changed, 28 insertions(+)
> >
> > diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
> > index 397df50..03801ed 100644
> > --- a/drivers/tty/serial/st-asc.c
> > +++ b/drivers/tty/serial/st-asc.c
> > @@ -37,10 +37,16 @@
> > #define ASC_FIFO_SIZE 16
> > #define ASC_MAX_PORTS 8
> >
> > +/* Pinctrl states */
> > +#define DEFAULT 0
> > +#define MANUAL_RTS 1
>
> Nit: Would be better to have them aligned.

These are aligned in code. The patch format throws things out.

Look, same lines with the "> > +" removed:

/* Pinctrl states */
#define DEFAULT 0
#define MANUAL_RTS 1

Try it.

> > +
> > struct asc_port {
> > struct uart_port port;
> > struct gpio_desc *rts;
> > struct clk *clk;
> > + struct pinctrl *pinctrl;
> > + struct pinctrl_state *states[2];
> > unsigned int hw_flow_control:1;
> > unsigned int force_m1:1;
> > };
> > @@ -694,6 +700,7 @@ static int asc_init_port(struct asc_port *ascport,
> > {
> > struct uart_port *port = &ascport->port;
> > struct resource *res;
> > + int ret;
> >
> > port->iotype = UPIO_MEM;
> > port->flags = UPF_BOOT_AUTOCONF;
> > @@ -720,6 +727,27 @@ static int asc_init_port(struct asc_port *ascport,
> > WARN_ON(ascport->port.uartclk == 0);
> > clk_disable_unprepare(ascport->clk);
> >
> > + ascport->pinctrl = devm_pinctrl_get(&pdev->dev);
> > + if (IS_ERR(ascport->pinctrl)) {
> > + ret = PTR_ERR(ascport->pinctrl);
> > + dev_err(&pdev->dev, "Failed to get Pinctrl: %d\n", ret);
> > + }
> > +
> > + ascport->states[DEFAULT] =
> > + pinctrl_lookup_state(ascport->pinctrl, "default");
> > + if (IS_ERR(ascport->states[DEFAULT])) {
> > + ret = PTR_ERR(ascport->states[DEFAULT]);
> > + dev_err(&pdev->dev,
> > + "Failed to look up Pinctrl state 'default': %d\n", ret);
> > + return ret;
> > + }
> > +
> > + /* "manual-rts" state is optional */
> > + ascport->states[MANUAL_RTS] =
> > + pinctrl_lookup_state(ascport->pinctrl, "manual-rts");
> > + if (IS_ERR(ascport->states[MANUAL_RTS]))
> > + ascport->states[MANUAL_RTS] = NULL;
> > +
>
> The different pinctrl states looks like a neat solution to the problem.
>
> My only concern here is that 'default' state is implying a hw-flow-control
> pinmux config, and manual-rts is implying what is the current upstream
> 'default' pinmux config.
>
> Which maybe ok if you update all uarts, but currently only serial0
> is updated. So the other uarts current 'default' is actually the same as serial0
> 'manual-rts' grouping, which conceptually is odd.
>
> Would it not be better to make 'manual-rts' the default state? As that aligns
> to what is currently already the default for the other UARTS? And then make
> hw-flow-control the optional state for serial0?
>
> That also has the advantage that 'default' has the same meaning with older DT's.

The reason it was done is this was because none of the other UARTs
require 2 separate Pinctrl configurations, only this one. Moreover,
if they support RTS/CTS then I believe that the lines should be
defined in Pinctrl. Thus, it was my plan to update all UART's default
Pinctrl configs to include the RTS/CTS lines.

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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