[6/6] phy: qcom-qmp-combo: fix type-c switch registration

Due to a long-standing issue in driver core, drivers may not probe defer
after having registered child devices to avoid triggering a probe
deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
-EPROBE_DEFER")).

Move registration of the typec switch to after looking up clocks and
other resources.

Note that PHY creation can in theory also trigger a probe deferral when
a 'phy' supply is used. This does not seem to affect the QMP PHY driver
but the PHY subsystem should be reworked to address this (i.e. by
separating initialisation and registration of the PHY).

Fixes: 2851117f8f42 ("phy: qcom-qmp-combo: Introduce orientation switching")
Cc: stable@vger.kernel.org      # 6.5
Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

On Sat, Feb 17, 2024 at 04:02:28PM +0100, Johan Hovold wrote:
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
> 
> Move registration of the typec switch to after looking up clocks and
> other resources.
> 
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).
> 
> Fixes: 2851117f8f42 ("phy: qcom-qmp-combo: Introduce orientation switching")
> Cc: stable@vger.kernel.org      # 6.5
> Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Bjorn Andersson <andersson@kernel.org>

Regards,
Bjorn

> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> index e19d6a084f10..17c4ad7553a5 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> @@ -3562,10 +3562,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	ret = qmp_combo_typec_switch_register(qmp);
> -	if (ret)
> -		return ret;
> -
>  	/* Check for legacy binding with child nodes. */
>  	usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
>  	if (usb_np) {
> @@ -3585,6 +3581,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto err_node_put;
>  
> +	ret = qmp_combo_typec_switch_register(qmp);
> +	if (ret)
> +		goto err_node_put;
> +
>  	ret = drm_aux_bridge_register(dev);
>  	if (ret)
>  		goto err_node_put;
> -- 
> 2.43.0
>

On Sat, 17 Feb 2024 at 17:03, Johan Hovold <johan+linaro@kernel.org> wrote:
>
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
>
> Move registration of the typec switch to after looking up clocks and
> other resources.
>
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).
>
> Fixes: 2851117f8f42 ("phy: qcom-qmp-combo: Introduce orientation switching")
> Cc: stable@vger.kernel.org      # 6.5
> Cc: Bjorn Andersson <quic_bjorande@quicinc.com>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  drivers/phy/qualcomm/phy-qcom-qmp-combo.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Note to myself (or to anybody else, who has spare hands), we should
probably implement the same changes for phy-qcom-qmp-usbc.c

>
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> index e19d6a084f10..17c4ad7553a5 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-combo.c
> @@ -3562,10 +3562,6 @@ static int qmp_combo_probe(struct platform_device *pdev)
>         if (ret)
>                 return ret;
>
> -       ret = qmp_combo_typec_switch_register(qmp);
> -       if (ret)
> -               return ret;
> -
>         /* Check for legacy binding with child nodes. */
>         usb_np = of_get_child_by_name(dev->of_node, "usb3-phy");
>         if (usb_np) {
> @@ -3585,6 +3581,10 @@ static int qmp_combo_probe(struct platform_device *pdev)
>         if (ret)
>                 goto err_node_put;
>
> +       ret = qmp_combo_typec_switch_register(qmp);
> +       if (ret)
> +               goto err_node_put;
> +
>         ret = drm_aux_bridge_register(dev);
>         if (ret)
>                 goto err_node_put;
> --
> 2.43.0
>

On 17-02-24, 16:02, Johan Hovold wrote:
> Due to a long-standing issue in driver core, drivers may not probe defer
> after having registered child devices to avoid triggering a probe
> deferral loop (see fbc35b45f9f6 ("Add documentation on meaning of
> -EPROBE_DEFER")).
> 
> Move registration of the typec switch to after looking up clocks and
> other resources.
> 
> Note that PHY creation can in theory also trigger a probe deferral when
> a 'phy' supply is used. This does not seem to affect the QMP PHY driver
> but the PHY subsystem should be reworked to address this (i.e. by
> separating initialisation and registration of the PHY).

Acked-by: Vinod Koul <vkoul@kernel.org>