On Wed, Apr 24, 2024 at 05:16:57AM +0300, Dmitry Baryshkov wrote:
> If a probe function returns -EPROBE_DEFER after creating another device
> there is a change of ending up in a probe deferral loop, (see commit
> fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER"). In case
> of the qcom-pmic-typec driver the tcpm_register_port() function looks up
> external resources (USB role switch and inherently via called
> typec_register_port() USB-C muxes, switches and retimers).
>
> In order to prevent such probe-defer loops caused by qcom-pmic-typec
> driver, use the API added by Johan Hovold and move HPD bridge
> registration to the end of the probe function.
>
> The devm_drm_dp_hpd_bridge_add() is called at the end of the probe
> function after all TCPM start functions. This is done as a way to
> overcome a different problem, the DRM subsystem can not properly cope
> with the DRM bridges being destroyed once the bridge is attached. Having
> this function call at the end of the probe function prevents possible
> DRM bridge device creation followed by destruction in case one of the
> TCPM start functions returns an error.
>
> Reported-by: Caleb Connolly <caleb.connolly@xxxxxxxxxx>
> Acked-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> ---
> Dependency: https://lore.kernel.org/lkml/20240418145730.4605-2-johan+linaro@xxxxxxxxxx/
> ---
> Changes in v4:
> - Rebased on top of Johan's patches
> - Link to v3: https://lore.kernel.org/r/20240416-qc-pmic-typec-hpd-split-v3-1-fd071e3191a1@xxxxxxxxxx
>
> Changes in v3:
> - Updated commit message to explain my decisions (Johan).
> - Link to v2: https://lore.kernel.org/r/20240408-qc-pmic-typec-hpd-split-v2-1-1704f5321b73@xxxxxxxxxx
>
> Changes in v2:
> - Fix commit message (Bryan)
> - Link to v1: https://lore.kernel.org/r/20240405-qc-pmic-typec-hpd-split-v1-1-363daafb3c36@xxxxxxxxxx
> ---
> drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c | 10 ++++++++--
> 1 file changed, 8 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 d3958c061a97..501eddb294e4 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);
>
> @@ -110,8 +110,14 @@ static int qcom_pmic_typec_probe(struct platform_device *pdev)
> if (ret)
> goto port_stop;
>
> + ret = devm_drm_dp_hpd_bridge_add(tcpm->dev, bridge_dev);
> + if (ret)
> + goto pdphy_stop;
> +
> return 0;
>
> +pdphy_stop:
> + tcpm->pdphy_stop(tcpm);
> port_stop:
> tcpm->port_stop(tcpm);
> port_unregister:
>
> ---
> base-commit: 15d419fa23ecc51e388a369bbeaf3b47b0b5c76a
> change-id: 20240405-qc-pmic-typec-hpd-split-22804201902b
>
> Best regards,
> --
> Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
--
heikki
