linux-kernel - Re: [PATCH] usb: typec: qcom-pmic-typec: split HPD bridge alloc and registration

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Date: Sat, 6 Apr 2024 23:03:17 +0100
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konrad.dybcio@...aro.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
 linux-kernel@...r.kernel.org, Caleb Connolly <caleb.connolly@...aro.org>,
 Johan Hovold <johan+linaro@...nel.org>
Subject: Re: [PATCH] usb: typec: qcom-pmic-typec: split HPD bridge alloc and
 registration

On 05/04/2024 19:11, Dmitry Baryshkov wrote:
> If a probe function returns -EPROBE_DEFER after creating another device
> there is a change of ening up in a probe deferral loop, (see commit

*ending

> fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER").
> 
> In order to prevent such probe-defer loops caused by qcom-pmic-typec
> driver, use the API added by Johan Hoval and move HPD bridge

*Hovold

> registeration to the end of the probe function.

registration

> 
> Reported-by: Caleb Connolly <caleb.connolly@...aro.org>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>   drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c
> index e48412cdcb0f..96b41efae318 100644
> --- a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c
> +++ b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c
> @@ -41,7 +41,7 @@ static int qcom_pmic_typec_probe(struct platform_device *pdev)
>   	struct device_node *np = dev->of_node;
>   	const struct pmic_typec_resources *res;
>   	struct regmap *regmap;
> -	struct device *bridge_dev;
> +	struct auxiliary_device *bridge_dev;
>   	u32 base;
>   	int ret;
>   
> @@ -92,7 +92,7 @@ static int qcom_pmic_typec_probe(struct platform_device *pdev)
>   	if (!tcpm->tcpc.fwnode)
>   		return -EINVAL;
>   
> -	bridge_dev = drm_dp_hpd_bridge_register(tcpm->dev, to_of_node(tcpm->tcpc.fwnode));
> +	bridge_dev = devm_drm_dp_hpd_bridge_alloc(tcpm->dev, to_of_node(tcpm->tcpc.fwnode));
>   	if (IS_ERR(bridge_dev))
>   		return PTR_ERR(bridge_dev);
>   
> @@ -110,6 +110,10 @@ static int qcom_pmic_typec_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto fwnode_remove;
>   
> +	ret = devm_drm_dp_hpd_bridge_add(tcpm->dev, bridge_dev);
> +	if (ret)
> +		goto fwnode_remove;
> +

Is there any reason this call comes after port_start/pdphy_start ?

I think the bridge add should go before starting the typec port and 
pdphy since after the start calls IRQs are enabled.

With those minor points addressed

Acked-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>

---
bod