Re: [PATCH 1/2] tty: amba-pl011: add support for clock frequency setting via dt

[Jorge Ramirez]

On 07/09/2016 02:43 AM, Stephen Boyd wrote:
> On 07/08/2016 05:23 PM, Michael Turquette wrote:
> > Quoting Jorge Ramirez (2016-07-08 14:39:50)
> > > On 07/08/2016 07:14 PM, Michael Turquette wrote:
> > > > Quoting Jorge Ramirez-Ortiz (2016-07-08 01:11:06)
> > > > > Allow to specify the clock frequency for any given port via the
> > > > > assigned-clock-rates device tree property.
> > > > >
> > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@xxxxxxxxxx>
> > > > > Tested-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@xxxxxxxxxx>
> > > > > ---
> > > > >    drivers/tty/serial/amba-pl011.c | 5 +++++
> > > > >    1 file changed, 5 insertions(+)
> > > > >
> > > > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> > > > > index 1b7331e..51867ab 100644
> > > > > --- a/drivers/tty/serial/amba-pl011.c
> > > > > +++ b/drivers/tty/serial/amba-pl011.c
> > > > > @@ -55,6 +55,7 @@
> > > > >    #include <linux/types.h>
> > > > >    #include <linux/of.h>
> > > > >    #include <linux/of_device.h>
> > > > > +#include <linux/clk/clk-conf.h>
> > > > >    #include <linux/pinctrl/consumer.h>
> > > > >    #include <linux/sizes.h>
> > > > >    #include <linux/io.h>
> > > > > @@ -2472,6 +2473,10 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
> > > > >           if (IS_ERR(uap->clk))
> > > > >                   return PTR_ERR(uap->clk);
> > > > >    
> > > > > +       ret = of_clk_set_defaults(dev->dev.of_node, false);
> > > > Change looks good to me, but with one question: should this change be
> > > > put into more generic code instead of in this specific driver? For
> > > > instance, we call of_clk_set_defaults from the following files:
> > > >
> > > > drivers/base/platform.c
> > > > drivers/i2c/i2c-core.c
> > > > drivers/spi/spi.c
> > > >
> > > > And Stephen posted a patch to do this for devices on the AMBA bus:
> > > >
> > > > https://patchwork.kernel.org/patch/6501691/
> > > >
> > > > Does Stephen's patch mean that you do not need patch #1?
> > > I did a quick test (replaced my changes with the patch above) and the
> > > console broke and the BT stack couldn't communicate to the device over
> > > the uart...I guess something else needs doing on top of Stephen's change.
> > Let's give Stephen a chance to respond. If he doesn't soon then I'm OK
> > to merge your two patches.
>
> Yeah we need to restart that patch. It's been in my "pending" list for a
> year now it seems.
>
> Curious why it broke things, perhaps device probe is failing when it
> didn't fail before?

um, I retested again this morning and it is all good - I was also a bit 
surprised when things failed yesterday  (it seems one of the wires on my 
board was loose, sorry).

So AFAIC your patch addresses the issue in a much generic (better) way 
and there are no regressions on a HiKey board running a 4.4 kernel.