Re: [PATCH v7 4/5] dt-bindings: phy: realtek: Add Realtek DHC RTD SoC USB 2.0 PHY

Re: [PATCH v7 4/5] dt-bindings: phy: realtek: Add Realtek DHC RTD SoC USB 2.0 PHY

[Rob Herring]

On Fri, 07 Jul 2023 14:47:03 +0800, Stanley Chang wrote:
> Document the USB PHY bindings for Realtek SoCs.
> Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
> controller and using USB 2.0 PHY transceiver.
> 
> Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
> ---
> v6 to v7 change:
>     1. Revise the commit message
>     2. Change the property name for realtek,driving-level-compensate
>     3. Add if/then schema for specific properties
> v5 to v6 change:
>     Drop the redundant examples
>     Drop the label of example
> v4 to v5 change:
>     1. Add more examples.
>     2. Remove the compatible realtek,usb2phy.
>     3. Revise the descriptor of the property.
>     4. Add the default of the property.
> v3 to v4 change:
>     1. Remove the parameter and non hardware properties from dts.
>     2. Using the compatible data included the config and parameter
>        in driver.
> v2 to v3 change:
>     1. Broken down into two patches, one for each of USB 2 & 3.
>     2. Add more description about Realtek RTD SoCs architecture.
>     3. Removed parameter v1 support for simplification.
>     4. Revised the compatible name for fallback compatible.
>     5. Remove some properties that can be set in the driver.
> v1 to v2 change:
>     Add phy-cells for generic phy driver
> ---
>  .../bindings/phy/realtek,usb2phy.yaml         | 175 ++++++++++++++++++
>  1 file changed, 175 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/phy/realtek,usb2phy.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>


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Re: [PATCH v7 5/5] dt-bindings: phy: realtek: Add Realtek DHC RTD SoC USB 3.0 PHY

[Rob Herring]

On Fri, 07 Jul 2023 14:47:04 +0800, Stanley Chang wrote:
> Document the USB PHY bindings for Realtek SoCs.
> Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
> controller and using USB 3.0 PHY transceiver.
> 
> Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
> ---
> v6 to v7 change:
>     Revise the commit message.
> v5 to v6 change:
>     Drop the labels of example.
> v4 to v5 change:
>     1. Remove the compatible realtek,usb3phy.
>     2. Add the default of the property.
> v3 to v4 change:
>     1. Remove the parameter and non hardware properties from dts.
>     2. Using the compatible data included the config and parameter
>        in driver.
> v2 to v3 change:
>     1. Broken down into two patches, one for each of USB 2 & 3.
>     2. Add more description about Realtek RTD SoCs architecture.
>     3. Removed parameter v1 support for simplification.
>     4. Revised the compatible name for fallback compatible.
>     5. Remove some properties that can be set in the driver.
> v1 to v2 change:
>     Add phy-cells for generic phy driver
> ---
>  .../bindings/phy/realtek,usb3phy.yaml         | 107 ++++++++++++++++++
>  1 file changed, 107 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/phy/realtek,usb3phy.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>


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Re: [PATCH v7 1/5] usb: phy: add usb phy notify port status API

[Greg Kroah-Hartman]

On Fri, Jul 07, 2023 at 02:47:00PM +0800, Stanley Chang wrote:
> In Realtek SoC, the parameter of usb phy is designed to can dynamic
> tuning base on port status. Therefore, add a notify callback of phy
> driver when usb port status change.
> 
> The Realtek phy driver is designed to dynamically adjust disconnection
> level and calibrate phy parameters. When the device connected bit changes
> and when the disconnected bit changes, do port status change notification:
> 
> Check if portstatus is USB_PORT_STAT_CONNECTION and portchange is
> USB_PORT_STAT_C_CONNECTION.
> 1. The device is connected, the driver lowers the disconnection level and
>    calibrates the phy parameters.
> 2. The device disconnects, the driver increases the disconnect level and
>    calibrates the phy parameters.
> 
> When controller to notify connect that device is already ready. If we
> adjust the disconnection level in notify_connect, the disconnect may have
> been triggered at this stage. So we need to change that as early as
> possible. Therefore, we add an api to notify phy the port status changes.

How do you know that the disconnect will not have already been triggered
at this point, when the status changes?


> 
> Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
> ---
> v6 to v7 change:
>     No change
> v5 to v6 change:
>     No change
> v4 to v5 change:
>     No change
> v3 to v4 change:
>     Fix the warning for checkpatch with strict.
> v2 to v3 change:
>     Add more comments about the reason for adding this api
> v1 to v2 change:
>     No change
> ---
>  drivers/usb/core/hub.c  | 13 +++++++++++++
>  include/linux/usb/phy.h | 13 +++++++++++++
>  2 files changed, 26 insertions(+)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index a739403a9e45..8433ff89dea6 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -614,6 +614,19 @@ static int hub_ext_port_status(struct usb_hub *hub, int port1, int type,
>  		ret = 0;
>  	}
>  	mutex_unlock(&hub->status_mutex);
> +
> +	if (!ret) {
> +		struct usb_device *hdev = hub->hdev;
> +
> +		if (hdev && !hdev->parent) {

Why the check for no parent?  Please document that here in a comment.

> +			struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
> +
> +			if (hcd->usb_phy)
> +				usb_phy_notify_port_status(hcd->usb_phy,
> +							   port1 - 1, *status, *change);
> +		}
> +	}
> +

This is safe to notify with the hub mutex unlocked?  Again, a comment
would be helpful to future people explaining why that is so.

thanks,

greg k-h

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Re: [PATCH v7 1/5] usb: phy: add usb phy notify port status API

[Greg Kroah-Hartman]

On Mon, Jul 24, 2023 at 06:49:50AM +0000, Stanley Chang[昌育德] wrote:
> 
> > 
> > On Fri, Jul 07, 2023 at 02:47:00PM +0800, Stanley Chang wrote:
> > > In Realtek SoC, the parameter of usb phy is designed to can dynamic
> > > tuning base on port status. Therefore, add a notify callback of phy
> > > driver when usb port status change.
> > >
> > > The Realtek phy driver is designed to dynamically adjust disconnection
> > > level and calibrate phy parameters. When the device connected bit
> > > changes and when the disconnected bit changes, do port status change
> > notification:
> > >
> > > Check if portstatus is USB_PORT_STAT_CONNECTION and portchange is
> > > USB_PORT_STAT_C_CONNECTION.
> > > 1. The device is connected, the driver lowers the disconnection level and
> > >    calibrates the phy parameters.
> > > 2. The device disconnects, the driver increases the disconnect level and
> > >    calibrates the phy parameters.
> > >
> > > When controller to notify connect that device is already ready. If we
> > > adjust the disconnection level in notify_connect, the disconnect may
> > > have been triggered at this stage. So we need to change that as early
> > > as possible. Therefore, we add an api to notify phy the port status changes.
> > 
> > How do you know that the disconnect will not have already been triggered at
> > this point, when the status changes?
> 
> The status change of connection is before port reset.
> In this stage, the device is not port enable, and it will not trigger disconnection.

Ok, then say that here please :)

> > >
> > > Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
> > > ---
> > > v6 to v7 change:
> > >     No change
> > > v5 to v6 change:
> > >     No change
> > > v4 to v5 change:
> > >     No change
> > > v3 to v4 change:
> > >     Fix the warning for checkpatch with strict.
> > > v2 to v3 change:
> > >     Add more comments about the reason for adding this api
> > > v1 to v2 change:
> > >     No change
> > > ---
> > >  drivers/usb/core/hub.c  | 13 +++++++++++++  include/linux/usb/phy.h |
> > > 13 +++++++++++++
> > >  2 files changed, 26 insertions(+)
> > >
> > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index
> > > a739403a9e45..8433ff89dea6 100644
> > > --- a/drivers/usb/core/hub.c
> > > +++ b/drivers/usb/core/hub.c
> > > @@ -614,6 +614,19 @@ static int hub_ext_port_status(struct usb_hub *hub,
> > int port1, int type,
> > >               ret = 0;
> > >       }
> > >       mutex_unlock(&hub->status_mutex);
> > > +
> > > +     if (!ret) {
> > > +             struct usb_device *hdev = hub->hdev;
> > > +
> > > +             if (hdev && !hdev->parent) {
> > 
> > Why the check for no parent?  Please document that here in a comment.
> 
> I will add a comment :
> /* Only notify roothub. That is, when hdev->parent is empty. */

Also document this that this will only happen for root hub status
changes, that's not obvious in the callback name or documentation or
anywhere else here.

> > > +                     struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
> > > +
> > > +                     if (hcd->usb_phy)
> > > +
> > usb_phy_notify_port_status(hcd->usb_phy,
> > > +                                                        port1 -
> > 1, *status, *change);
> > > +             }
> > > +     }
> > > +
> > 
> > This is safe to notify with the hub mutex unlocked?  Again, a comment would
> > be helpful to future people explaining why that is so.
> > 
> 
> I will add a comment: 
> /*                                                                      
>  * There is no need to lock status_mutex here, because status_mutex     
>  * protects hub->status, and the phy driver only checks the port        
>  * status without changing the status.                                  
>  */  

Looks good, if you do it without the trailing whitespace :)

thanks,

greg k-h

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