Re: [PATCH] usb: typec: fusb302: add DRM DP HPD bridge support

[Alexey Charkov]

Hi Sebastian,

On Tue, Mar 10, 2026 at 9:17 PM Sebastian Reichel
<sebastian.reichel@xxxxxxxxxxxxx> wrote:
>
> Add support to use fusb302 based USB-C connectors with the DP altmode
> helper code on devicetree based platforms. To get this working there
> must be a DRM bridge chain from the DisplayPort controller to the USB-C
> connector. E.g. on Rockchip RK3576:
>
> root@rk3576 # cat /sys/kernel/debug/dri/0/encoder-0/bridges
> bridge[0]: dw_dp_bridge_funcs
>         refcount: 7
>         type: [10] DP
>         OF: /soc/dp@27e40000:rockchip,rk3576-dp
>         ops: [0x47] detect edid hpd
> bridge[1]: drm_aux_bridge_funcs
>         refcount: 4
>         type: [0] Unknown
>         OF: /soc/phy@2b010000:rockchip,rk3576-usbdp-phy
>         ops: [0x0]
> bridge[2]: drm_aux_hpd_bridge_funcs
>         refcount: 5
>         type: [10] DP
>         OF: /soc/i2c@2ac50000/typec-portc@22/connector:usb-c-connector
>         ops: [0x4] hpd
>
> Signed-off-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
> ---
> To make this usable on Rockchip RK3588 and RK3576 platforms as shown in
> the commit message, the Designware DP driver and the USBDP PHY driver
> also need changes. Those are being send separately as the fusb302 patch
> can be merged completley independently.
> ---
>  drivers/usb/typec/tcpm/Kconfig   |  2 ++
>  drivers/usb/typec/tcpm/fusb302.c | 13 +++++++++++++
>  2 files changed, 15 insertions(+)
>
> diff --git a/drivers/usb/typec/tcpm/Kconfig b/drivers/usb/typec/tcpm/Kconfig
> index 8cdd84ca5d6f..00baa7503d45 100644
> --- a/drivers/usb/typec/tcpm/Kconfig
> +++ b/drivers/usb/typec/tcpm/Kconfig
> @@ -58,6 +58,8 @@ config TYPEC_FUSB302
>         tristate "Fairchild FUSB302 Type-C chip driver"
>         depends on I2C
>         depends on EXTCON || !EXTCON
> +       depends on DRM || DRM=n
> +       select DRM_AUX_HPD_BRIDGE if DRM_BRIDGE && OF
>         help
>           The Fairchild FUSB302 Type-C chip driver that works with
>           Type-C Port Controller Manager to provide USB PD and USB
> diff --git a/drivers/usb/typec/tcpm/fusb302.c b/drivers/usb/typec/tcpm/fusb302.c
> index 19ff8217818e..ce7069fb4be6 100644
> --- a/drivers/usb/typec/tcpm/fusb302.c
> +++ b/drivers/usb/typec/tcpm/fusb302.c
> @@ -5,6 +5,7 @@
>   * Fairchild FUSB302 Type-C Chip Driver
>   */
>
> +#include <drm/bridge/aux-bridge.h>
>  #include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/errno.h>
> @@ -1689,6 +1690,7 @@ static int fusb302_probe(struct i2c_client *client)
>  {
>         struct fusb302_chip *chip;
>         struct i2c_adapter *adapter = client->adapter;
> +       struct auxiliary_device *bridge_dev;
>         struct device *dev = &client->dev;
>         const char *name;
>         int ret = 0;
> @@ -1747,6 +1749,13 @@ static int fusb302_probe(struct i2c_client *client)
>                 goto destroy_workqueue;
>         }
>
> +       bridge_dev = devm_drm_dp_hpd_bridge_alloc(chip->dev, to_of_node(chip->tcpc_dev.fwnode));
> +       if (IS_ERR(bridge_dev)) {
> +               ret = PTR_ERR(bridge_dev);
> +               dev_err_probe(chip->dev, ret, "failed to alloc bridge\n");
> +               goto destroy_workqueue;
> +       }
> +
>         chip->tcpm_port = tcpm_register_port(&client->dev, &chip->tcpc_dev);
>         if (IS_ERR(chip->tcpm_port)) {
>                 fwnode_handle_put(chip->tcpc_dev.fwnode);
> @@ -1764,6 +1773,10 @@ static int fusb302_probe(struct i2c_client *client)
>         enable_irq_wake(chip->gpio_int_n_irq);
>         i2c_set_clientdata(client, chip);
>
> +       ret = devm_drm_dp_hpd_bridge_add(chip->dev, bridge_dev);
> +       if (ret)
> +               return ret;
> +
>         return ret;

Nit: how about

return devm_drm_dp_hpd_bridge_add(chip->dev, bridge_dev);

Saves three lines :)

Thanks a lot,
Alexey