Re: [PATCH v2 1/4] iio: adc: rockchip_saradc: reset saradc controller before programming it

[Caesar Wang]

On 2016å07æ27æ 01:00, Guenter Roeck wrote:
> On Tue, Jul 26, 2016 at 10:47:16PM +0800, Caesar Wang wrote:
> > On 2016å07æ26æ 21:39, Guenter Roeck wrote:
> > > > static int rockchip_saradc_probe(struct platform_device *pdev)
> > > > {
> > > > struct rockchip_saradc *info = NULL;
> > > > @@ -218,6 +231,21 @@ static int rockchip_saradc_probe(struct
> > > > platform_device *pdev)
> > > > if (IS_ERR(info->regs))
> > > > return PTR_ERR(info->regs);
> > > >
> > > > + /*
> > > > + * The reset should be an optional property, as it should work
> > > > + * with old devicetrees as well
> > > > + */
> > > > + info->reset = devm_reset_control_get_optional(&pdev->dev,
> > > > + "saradc-apb");
> > > Does anyone know what the _optional API is for ? It seems to be exactly
> > > the same
> > > as devm_reset_control_get().
> > â
> > As far as I see, the difference is WARN_ON(1)
> > when CONFIG_RESET_CONTROLLER is not defined.
> >
> >
> > The _optional functions were introduced by the following commit:
> >
> > ----------------->8-----------------
> > commit b424080a9e086e683ad5fdc624a7cf3c024e0c0f
> > Author: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> > Date: Fri Mar 7 15:18:47 2014 +0100
> >
> > reset: Add optional resets and stubs
> >
> > This patch adds device_reset_optional and (devm_)reset_control_get_optional
> > variants that drivers can use to indicate they can function without control
> > over the reset line. For those functions, stubs are added so the drivers can
> > be compiled with CONFIG_RESET_CONTROLLER disabled.
> > Also, device_reset is annotated with __must_check. Drivers
> > ignoring the return
> > value should use device_reset_optional instead.
> Is that really what we are looking for here ? CONFIG_RESET_CONTROLLER
> is required for other functions of rk3399, isn't it ?

Right, as the DRM and thermal are depend on the CONFIG_RESET_CONTROLLER 
.....


> Guenter
>
> > Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> > ------------------8<-----------------------------
> > â
> >
> > for more information on http://www.spinics.net/lists/kernel/msg2306677.html
> > :-)
> >
> > > Guenter
> > >
> > > > + if (IS_ERR(info->reset)) {
> > > > + ret = PTR_ERR(info->reset);
> > > > + if (ret != -ENOENT)
> > > > + return ret;
> > > > +
> > > > + dev_dbg(&pdev->dev, "no reset control found\n");
> > > > + info->reset = NULL;
> > > > + }
> > > > +
> > > > init_completion(&info->completion);
> > > >
> > > > irq = platform_get_irq(pdev, 0);
> > > > @@ -252,6 +280,9 @@ static int rockchip_saradc_probe(struct
> > > > platform_device *pdev)
> > > > return PTR_ERR(info->vref);
> > > > }
> > > >
> > > > + if (info->reset)
> > > > + rockchip_saradc_reset_controller(info->reset);
> > > > +
> > > > /*
> > > > * Use a default value for the converter clock.
> > > > * This may become user-configurable in the future.
> > >
> > > _______________________________________________
> > > Linux-rockchip mailing list
> > > Linux-rockchip@xxxxxxxxxxxxxxxxxxx
> > > http://lists.infradead.org/mailman/listinfo/linux-rockchip
> >
> > --
> > caesar wang | software engineer | wxt@xxxxxxxxxxxxx
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-rockchip


--
caesar wang | software engineer | wxt@xxxxxxxxxxxxx