On Wed, Aug 31, 2016 at 03:07:56PM +0300, Heikki Krogerus wrote:
> Hi,
>
> On Wed, Aug 31, 2016 at 11:29:11AM +0800, Kefeng Wang wrote:
> > Make dw8250_set_termios() handle all cases of dw8250_data->clk properly,
> > then we can safely use dw8250_set_termios() as the default set_termios
> > callback instead of serial8250_do_set_termios(), so do it.
> >
> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > ---
> > drivers/tty/serial/8250/8250_dw.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> > index 5c0c123..adecece 100644
> > --- a/drivers/tty/serial/8250/8250_dw.c
> > +++ b/drivers/tty/serial/8250/8250_dw.c
> > @@ -235,7 +235,7 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
> > unsigned int rate;
> > int ret;
> >
> > - if (IS_ERR(d->clk) || !old)
> > + if (IS_ERR_OR_NULL(d->clk) || !old)
> > goto out;
>
> This part is fine, but...
>
> > clk_disable_unprepare(d->clk);
> > @@ -308,13 +308,11 @@ static void dw8250_quirks(struct uart_port *p, struct dw8250_data *data)
> > p->serial_in = dw8250_serial_in32;
> > data->uart_16550_compatible = true;
> > }
> > - p->set_termios = dw8250_set_termios;
> > }
> >
> > /* Platforms with iDMA */
> > if (platform_get_resource_byname(to_platform_device(p->dev),
> > IORESOURCE_MEM, "lpss_priv")) {
> > - p->set_termios = dw8250_set_termios;
> > data->dma.rx_param = p->dev->parent;
> > data->dma.tx_param = p->dev->parent;
> > data->dma.fn = dw8250_idma_filter;
> > @@ -391,6 +389,7 @@ static int dw8250_probe(struct platform_device *pdev)
> > p->iotype = UPIO_MEM;
> > p->serial_in = dw8250_serial_in;
> > p->serial_out = dw8250_serial_out;
> > + p->set_termios = dw8250_set_termios;
>
> I'm a bit worried about this. If I remember correctly, we didn't set
> the set_termios hook by default in the past because somebody was using
> a type of clk that can't handle rate rounding and ended up using
> improper clock frequency for some baud rates. Unfortunately I can't
> remember who had that problem and on which platform.
>
> On the other hand, I'm not sure if drivers should worry about things
> like that. This should be done the other way around. The platform
> with the problem should unset the p->set_termios hook in a quirk, but
> by default everybody would use dw8250_set_termios.
No comments... I would suggest we skip this for now. I don't think
it's necessary for Hisilicon Hip05 SoC support, so perhaps you can
just propose this change separately.
Thanks,
--
heikki
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
