linux-kernel - Re: [PATCH v9 06/10] phy: rockchip: phy-rockchip-typec: Add DRM AUX bridge

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Message-ID: <525040d5-84db-4de1-aed0-3b4b5a672f8b@rock-chips.com>
Date: Tue, 18 Nov 2025 17:37:39 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Neil Armstrong <neil.armstrong@...aro.org>,
 Chaoyi Chen <kernel@...kyi.com>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Peter Chen <hzpeterchen@...il.com>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Vinod Koul <vkoul@...nel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>, Heiko Stuebner
 <heiko@...ech.de>, Sandy Huang <hjc@...k-chips.com>,
 Andy Yan <andy.yan@...k-chips.com>,
 Yubing Zhang <yubing.zhang@...k-chips.com>,
 Frank Wang <frank.wang@...k-chips.com>,
 Andrzej Hajda <andrzej.hajda@...el.com>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Amit Sunil Dhamne <amitsd@...gle.com>, Dragan Simic <dsimic@...jaro.org>,
 Johan Jonker <jbx6244@...il.com>, Diederik de Haas <didi.debian@...ow.org>,
 Peter Robinson <pbrobinson@...il.com>
Cc: linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v9 06/10] phy: rockchip: phy-rockchip-typec: Add DRM AUX
 bridge

Hi Neil,

On 11/18/2025 5:08 PM, Neil Armstrong wrote:
> On 11/11/25 11:50, Chaoyi Chen wrote:
>> From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
>>
>> Using the DRM_AUX_BRIDGE helper to create the transparent DRM bridge
>> device.
>>
>> Signed-off-by: Chaoyi Chen <chaoyi.chen@...k-chips.com>
>> ---
>>
>> (no changes since v7)
>>
>> Changes in v6:
>> - Fix depend in Kconfig.
>>
>>   drivers/phy/rockchip/Kconfig              |  2 +
>>   drivers/phy/rockchip/phy-rockchip-typec.c | 52 +++++++++++++++++++++++
>>   2 files changed, 54 insertions(+)
>>
>> diff --git a/drivers/phy/rockchip/Kconfig b/drivers/phy/rockchip/Kconfig
>> index db4adc7c53da..bcb5476222fc 100644
>> --- a/drivers/phy/rockchip/Kconfig
>> +++ b/drivers/phy/rockchip/Kconfig
>> @@ -120,6 +120,8 @@ config PHY_ROCKCHIP_TYPEC
>>       tristate "Rockchip TYPEC PHY Driver"
>>       depends on OF && (ARCH_ROCKCHIP || COMPILE_TEST)
>>       depends on TYPEC || TYPEC=n
>> +    depends on DRM || DRM=n
>> +    select DRM_AUX_BRIDGE if DRM_BRIDGE
>>       select EXTCON
>>       select GENERIC_PHY
>>       select RESET_CONTROLLER
>> diff --git a/drivers/phy/rockchip/phy-rockchip-typec.c b/drivers/phy/rockchip/phy-rockchip-typec.c
>> index 1f5b4142cbe4..748a6eb8ad95 100644
>> --- a/drivers/phy/rockchip/phy-rockchip-typec.c
>> +++ b/drivers/phy/rockchip/phy-rockchip-typec.c
>> @@ -36,6 +36,7 @@
>>    * orientation, false is normal orientation.
>>    */
>>   +#include <linux/auxiliary_bus.h>
>>   #include <linux/clk.h>
>>   #include <linux/clk-provider.h>
>>   #include <linux/delay.h>
>> @@ -56,6 +57,7 @@
>>   #include <linux/phy/phy.h>
>>   #include <linux/usb/typec_dp.h>
>>   #include <linux/usb/typec_mux.h>
>> +#include <drm/bridge/aux-bridge.h>
>>     #define CMN_SSM_BANDGAP            (0x21 << 2)
>>   #define CMN_SSM_BIAS            (0x22 << 2)
>> @@ -415,6 +417,7 @@ struct rockchip_usb3phy_port_cfg {
>>     struct rockchip_typec_phy {
>>       struct device *dev;
>> +    struct auxiliary_device dp_port_dev;
>>       void __iomem *base;
>>       struct extcon_dev *extcon;
>>       struct typec_mux_dev *mux;
>> @@ -1299,6 +1302,51 @@ static void tcphy_typec_mux_unregister(void *data)
>>       typec_mux_unregister(tcphy->mux);
>>   }
>>   +static void tcphy_dp_port_dev_release(struct device *dev)
>> +{
>> +    struct auxiliary_device *adev = to_auxiliary_dev(dev);
>> +
>> +    of_node_put(adev->dev.of_node);
>> +}
>> +
>> +static void tcphy_dp_port_unregister_adev(void *_adev)
>> +{
>> +    struct auxiliary_device *adev = _adev;
>> +
>> +    auxiliary_device_delete(adev);
>> +    auxiliary_device_uninit(adev);
>> +}
>> +
>> +static int tcphy_aux_bridge_register(struct rockchip_typec_phy *tcphy, struct device_node *np)
>> +{
>> +    struct auxiliary_device *adev = &tcphy->dp_port_dev;
>> +    int ret;
>> +
>> +    adev->name = "dp_port";
>> +    adev->dev.parent = tcphy->dev;
>> +    adev->dev.of_node = of_node_get(np);
>> +    adev->dev.release = tcphy_dp_port_dev_release;
>> +
>> +    ret = auxiliary_device_init(adev);
>> +
>
> Drop this empty line.

>
>> +    if (ret) {
>> +        of_node_put(adev->dev.of_node);
>> +        return ret;
>> +    }
>> +
>> +    ret = auxiliary_device_add(adev);
>> +    if (ret) {
>> +        auxiliary_device_uninit(adev);
>> +        return ret;
>> +    }
>> +
>> +    devm_add_action_or_reset(tcphy->dev, tcphy_dp_port_unregister_adev, adev);
>> +
>> +    ret = drm_aux_bridge_register(&adev->dev);
>
> Adding an aux device to an aux device looks quite overengineered to me !
>
> If it's a matter of using the proper of_node, you may instead create a separate
> drm_aux_bridge_register() like drm_aux_bridge_register_from_node() instead.

Yes, as you said, the aux device here is only to let the drm_aux_bridge get the correct of_node. I will add the API you mentioned in v10. Thank you.


-- 
Best,
Chaoyi