[PATCH v2] phy: phy-imx8mq-usb: add vbus regulator support

[Marek Vasut]

On 7/10/23 17:58, Tim Harvey wrote:
> On Mon, Jul 10, 2023 at 8:44 AM Marek Vasut <marex at denx.de> wrote:
>>
>> On 7/10/23 17:26, Tim Harvey wrote:
>>> On Sat, Jul 8, 2023 at 1:55 PM Marek Vasut <marex at denx.de> wrote:
>>>>
>>>> On 6/9/23 19:28, Tim Harvey wrote:
>>>>> Add support for enabling and disabling vbus-supply regulator found
>>>>> on several imx8mp boards in the usb3_phy0 and usb3_phy1 nodes.
>>>>>
>>>>> Signed-off-by: Tim Harvey <tharvey at gateworks.com>
>>>>> Reviewed-by: Adam Ford <aford173 at gmail.com>
>>>>> ---
>>>>> v2:
>>>>>     - protect ret with __maybe_unused in case CONFIG_CLK and
>>>>>       CONFIG_DM_REGULATOR not defined
>>>>>     - add error prints on failures
>>>>>     - add Adam's rb tag
>>>>> ---
>>>>>     drivers/phy/phy-imx8mq-usb.c | 32 ++++++++++++++++++++++++++++++--
>>>>>     1 file changed, 30 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/phy/phy-imx8mq-usb.c b/drivers/phy/phy-imx8mq-usb.c
>>>>> index 69f01de55538..53099436b04b 100644
>>>>> --- a/drivers/phy/phy-imx8mq-usb.c
>>>>> +++ b/drivers/phy/phy-imx8mq-usb.c
>>>>> @@ -14,6 +14,7 @@
>>>>>     #include <linux/delay.h>
>>>>>     #include <linux/err.h>
>>>>>     #include <clk.h>
>>>>> +#include <power/regulator.h>
>>>>>
>>>>>     #define PHY_CTRL0                   0x0
>>>>>     #define PHY_CTRL0_REF_SSP_EN                BIT(2)
>>>>> @@ -81,6 +82,7 @@ struct imx8mq_usb_phy {
>>>>>     #endif
>>>>>         void __iomem *base;
>>>>>         enum imx8mpq_phy_type type;
>>>>
>>>> Shouldn't this be in #if CONFIG_IS_ENABLED(DM_REGULATOR) ?
>>>>
>>>>> +     struct udevice *vbus_supply;
>>>
>>> Hi Marek,
>>>
>>> No, the usage of it is within an 'if (CONFIG_IS_ENABLED(DM_REGULATOR)
>>> && imx_phy->vbus_supply)' statement
>>
>> Except if this is not ifdef'd out, the structure is larger for no good
>> reason if DM_REGULATOR is DISABLED.
> 
> ok, I see your point.
> 
>>
>>>>>     };
>>>>>
>>>>>     static const struct udevice_id imx8mq_usb_phy_of_match[] = {
>>>>> @@ -172,10 +174,10 @@ static int imx8mq_usb_phy_power_on(struct phy *usb_phy)
>>>>>     {
>>>>>         struct udevice *dev = usb_phy->dev;
>>>>>         struct imx8mq_usb_phy *imx_phy = dev_get_priv(dev);
>>>>> +     __maybe_unused int ret;
>>>>>         u32 value;
>>>>>
>>>>>     #if CONFIG_IS_ENABLED(CLK)
>>>>> -     int ret;
>>>>>         ret = clk_enable(&imx_phy->phy_clk);
>>>>>         if (ret) {
>>>>>                 printf("Failed to enable usb phy clock\n");
>>>>> @@ -183,6 +185,14 @@ static int imx8mq_usb_phy_power_on(struct phy *usb_phy)
>>>>>         }
>>>>>     #endif
>>>>>
>>>>> +     if (CONFIG_IS_ENABLED(DM_REGULATOR) && imx_phy->vbus_supply) {
>>>>> +             ret = regulator_set_enable(imx_phy->vbus_supply, true);
>>>>> +             if (ret) {
>>>>> +                     pr_err("Failed to enable VBUS regulator: %d\n", ret);
>>>>
>>>> You do need to disable clock enabled above.
>>>
>>> it does get disabled in imx8mq_usb_phy_power_off()
>>
>> If that called if power_on returns -ERRNO ?
> 
> sorry, I don't quite understand.
> 
> Are you asking me to add a regulator disable in a remove function to
> make sure it's disabled if removed or are you saying that I shouldn't
> return the error from regulator_set_enable from
> imx8mq_usb_phy_power_on?

Actually, neither. There is clk_enable() a bit higher up in this 
power_on function. You need to stop the clock if this 
regulator_set_enable() return -ERRNO.

>>>> This likely needs a fail path with "err: ... return ret;"
>>>
>>> there are no further conditional return paths in this function.
>>
>> I suspect there should be.
> 
> again, I don't understand. The only thing remaining in this function
> is disable rx term override below so I don't see the point in adding a
> goto around that if that is what you are suggesting.
> 
> I don't really know what 'rx term override' is either... perhaps the
> regulator_set_enable should go after that?

Its only a matter of disabling the clock if the regulator enable fails 
and we bail out, that's all. Does it make sense now ?