Re: [PATCH v3] drm/bridge: analogix_dp: use devm_phy_optional_get() for the DP PHY

[Damon Ding <damon.ding@rock-chips.com>]

On 11/12/2026 11:39 PM, Luca Ceresoli wrote:
> Hello,
> 
> On Tue Nov 10, 2026 at 3:37 AM CET, Jun Yan wrote:
>> The DP PHY is optional: the Rockchip RK3399 eDP controller (used as the
>> internal eDP port) has no separate PHY device and relies on its built-in
>> PHY, which is programmed directly through the GRF registers, so its DT
>> node carries no "phys"/"phy-names" property.
>>
>> Requesting the PHY with devm_phy_get() therefore returns -ENODEV (or
>> -ENOSYS when CONFIG_GENERIC_PHY is disabled) and the driver logs a
>> misleading "no DP phy configured" error at probe time before falling back
>> to a NULL phy.
>>
>> Use devm_phy_optional_get() instead, which returns NULL when the PHY is
>> absent and otherwise behaves identically, and drop the manual -ENODEV/
>> -ENOSYS handling. This also removes the spurious error message.
>>
>> Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>
>> Reviewed-by: Damon Ding <damon.ding@rock-chips.com>
>> ---
>> Changes in v3:
>>    - Add missing changelog entries and reference links
>>    - Link to v2: https://lore.kernel.org/dri-devel/20261013134659.335829-1-jerrysteve1101@gmail.com/
>>
>> Changes in v2:
>>    - Added comments to explain the changes made.
>>    - Link to v1: https://lore.kernel.org/dri-devel/20260924020417.868588-1-jerrysteve1101@gmail.com/
>>
>>   .../drm/bridge/analogix/analogix_dp_core.c    | 22 ++++++-------------
>>   1 file changed, 7 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index 6df6963740d2..637b1bff0f6c 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -1426,21 +1426,13 @@ analogix_dp_probe(struct device *dev, struct analogix_dp_plat_data *plat_data)
>>   	if (ret)
>>   		return ERR_PTR(ret);
>>
>> -	dp->phy = devm_phy_get(dp->dev, "dp");
>> -	if (IS_ERR(dp->phy)) {
>> -		dev_err(dp->dev, "no DP phy configured\n");
>> -		ret = PTR_ERR(dp->phy);
>> -		if (ret) {
>> -			/*
>> -			 * phy itself is not enabled, so we can move forward
>> -			 * assigning NULL to phy pointer.
>> -			 */
>> -			if (ret == -ENOSYS || ret == -ENODEV)
>> -				dp->phy = NULL;
>> -			else
>> -				return ERR_PTR(ret);
>> -		}
>> -	}
>> +	/*
>> +	 * RK3288/RK3399 use Analogix DP controller built-in PHY,
>> +	 * no extra PHY configuration is required.
>> +	 */
>> +	dp->phy = devm_phy_optional_get(dp->dev, "dp");
>> +	if (IS_ERR(dp->phy))
>> +		return ERR_CAST(dp->phy);
> 
> The original code ignbores -ENOSYS, devm_phy_optional_get() does not. So,
> either -ENOSYS was just impossible, or this patch potentially changes the
> behaviour.
> 
> Can you elaborate on that?
> 
> 

You are right, this is really a valid concern.

If CONFIG_GENERIC_PHY is disabled, the old code could still proceed and 
keep the driver probing, while the new version would return an error 
directly.

It should be better to keep the -ENOSYS handling to preserve the 
original behavior.

Best regards,
Damon