> -----Original Message-----
> From: Peter Rosin [mailto:p...@axentia.se]
> Sent: Thursday, 21 February, 2019 07:12 PM
> To: Pankaj Bansal <pankaj.ban...@nxp.com>; Leo Li <leoyang...@nxp.com>
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v2] drivers: mux: Add Generic regmap bitfield-based
> multiplexer in mmio-mux
>
> Hi!
>
> Much better, thanks! One nit below:
>
> On 2019-02-21 13:48, Pankaj Bansal wrote:
> > Generic register bitfield-based multiplexer that controls the
> > multiplexer producer defined under a parent node.
> > The driver corresponding to parent node provides register read/write
> > capabilities.
> >
> > Signed-off-by: Pankaj Bansal <pankaj.ban...@nxp.com>
> > ---
> >
> > Notes:
> > V2:
> > - removed seperate driver regmap.c and added the regmap function in
> mmio.c
> > based on compatible field, the syscon or regmap function would be
> > called
> > - Modified the KConfig as per Peter's comments
> >
> > drivers/mux/Kconfig | 12 ++++++------ drivers/mux/mmio.c | 6
> > +++++-
> > 2 files changed, 11 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig index
> > 7659d6c5f718..e5c571fd232c 100644
> > --- a/drivers/mux/Kconfig
> > +++ b/drivers/mux/Kconfig
> > @@ -46,14 +46,14 @@ config MUX_GPIO
> > be called mux-gpio.
> >
> > config MUX_MMIO
> > - tristate "MMIO register bitfield-controlled Multiplexer"
> > - depends on (OF && MFD_SYSCON) || COMPILE_TEST
> > + tristate "MMIO/Regmap register bitfield-controlled Multiplexer"
> > + depends on OF || COMPILE_TEST
> > help
> > - MMIO register bitfield-controlled Multiplexer controller.
> > + MMIO/Regmap register bitfield-controlled Multiplexer controller.
> >
> > - The driver builds multiplexer controllers for bitfields in a syscon
> > - register. For N bit wide bitfields, there will be 2^N possible
> > - multiplexer states.
> > + The driver builds multiplexer controllers for bitfields in either
> > + a syscon register or a driver regmap register. For N bit wide
> > + bitfields, there will be 2^N possible multiplexer states.
> >
> > To compile the driver as a module, choose M here: the module will
> > be called mux-mmio.
> > diff --git a/drivers/mux/mmio.c b/drivers/mux/mmio.c index
> > 935ac44aa209..37fbcde7f1fc 100644
> > --- a/drivers/mux/mmio.c
> > +++ b/drivers/mux/mmio.c
> > @@ -28,6 +28,7 @@ static const struct mux_control_ops mux_mmio_ops = {
> >
> > static const struct of_device_id mux_mmio_dt_ids[] = {
> > { .compatible = "mmio-mux", },
> > + { .compatible = "reg-mux", },
> > { /* sentinel */ }
> > };
> > MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids); @@ -43,7 +44,10 @@
> static
> > int mux_mmio_probe(struct platform_device *pdev)
> > int ret;
> > int i;
> >
> > - regmap = syscon_node_to_regmap(np->parent);
> > + if (of_device_is_compatible(np, "mmio-mux"))
> > + regmap = syscon_node_to_regmap(np->parent);
> > + else
> > + regmap = dev_get_regmap(dev->parent, NULL);
>
> dev_get_regmap() returns NULL on failure, so I think you need something like:
>
> regmap = dev_get_regmap(dev->parent, NULL) ?: ERR_PTR(-
> EINVAL);
>
> Or perhaps -ENODEV, -ENOTSUPP or something, not sure?
How about IS_ERR_OR_NULL just below this, where right now IS_ERR is being used ?
>
> Cheers,
> Peter
>
> > if (IS_ERR(regmap)) {
> > ret = PTR_ERR(regmap);
> > dev_err(dev, "failed to get regmap: %d\n", ret);
> >
