Re: [PATCH 04/14] usb: phy: nop: Handle power supply regulator for the PHY

Russell King - ARM Linux
2013-01-11T17:17:45Z

On Thu, Jan 10, 2013 at 06:51:24PM +0200, Roger Quadros wrote:
> We use "vcc" as the supply name for the PHY's power supply.
> The power supply will be enabled during .init() and disabled
> during .shutdown()
>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> drivers/usb/otg/nop-usb-xceiv.c | 18 ++++++++++++++++++
> 1 files changed, 18 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/otg/nop-usb-xceiv.c b/drivers/usb/otg/nop-usb-xceiv.c
> index 163f972..1c6db10 100644
> --- a/drivers/usb/otg/nop-usb-xceiv.c
> +++ b/drivers/usb/otg/nop-usb-xceiv.c
> @@ -33,11 +33,13 @@
> #include <linux/usb/nop-usb-xceiv.h>
> #include <linux/slab.h>
> #include <linux/clk.h>
> +#include <linux/regulator/consumer.h>
>
> struct nop_usb_xceiv {
> struct usb_phy phy;
> struct device *dev;
> struct clk *clk;
> + struct regulator *vcc;
> };
>
> static struct platform_device *pd;
> @@ -70,6 +72,11 @@ static int nop_init(struct usb_phy *phy)
> {
> struct nop_usb_xceiv *nop = dev_get_drvdata(phy->dev);
>
> + if (nop->vcc) {
> + if (regulator_enable(nop->vcc))
> + dev_err(phy->dev, "Failed to enable power\n");
> + }
> +
> if (nop->clk)
> clk_enable(nop->clk);
>
> @@ -82,6 +89,11 @@ static void nop_shutdown(struct usb_phy *phy)
>
> if (nop->clk)
> clk_disable(nop->clk);
> +
> + if (nop->vcc) {
> + if (regulator_disable(nop->vcc))
> + dev_err(phy->dev, "Failed to disable power\n");
> + }
> }
>
> static int nop_set_peripheral(struct usb_otg *otg, struct usb_gadget *gadget)
> @@ -157,6 +169,12 @@ static int nop_usb_xceiv_probe(struct platform_device *pdev)
> }
> }
>
> + nop->vcc = devm_regulator_get(&pdev->dev, "vcc");
> + if (IS_ERR(nop->vcc)) {
> + dev_dbg(&pdev->dev, "Error getting vcc regulator\n");
> + nop->vcc = NULL;
> + }

Is it really appropriate for drivers to do this kind of thing with
pointer-returning functions (I mean, setting the pointer to NULL on
error, rather than just using a test for IS_ERR() in the above
locations). You are imposing driver-local assumptions on an API.

Practically it probably doesn't make much difference but given the
amount of mistakes that we have with IS_ERR_OR_NULL()...