linux-kernel - Re: [PATCH v20 4/9] usb: dwc3: core: Refactor PHY logic to support Multiport Controller

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Message-ID: <20240409011046.zgjqvhewldch3snu@synopsys.com>
Date: Tue, 9 Apr 2024 01:11:01 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Krishna Kurapati <quic_kriskura@...cinc.com>
CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
        Wesley Cheng <quic_wcheng@...cinc.com>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Felipe Balbi <balbi@...nel.org>, Johan Hovold <johan@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "quic_ppratap@...cinc.com" <quic_ppratap@...cinc.com>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>,
        Johan Hovold <johan+linaro@...nel.org>
Subject: Re: [PATCH v20 4/9] usb: dwc3: core: Refactor PHY logic to support
 Multiport Controller

On Mon, Apr 08, 2024, Krishna Kurapati wrote:
> Currently the DWC3 driver supports only single port controller
> which requires at least one HS PHY and at most one SS PHY.
> 
> But the DWC3 USB controller can be connected to multiple ports and
> each port can have their own PHYs. Each port of the multiport
> controller can either be HS+SS capable or HS only capable
> Proper quantification of them is required to modify GUSB2PHYCFG
> and GUSB3PIPECTL registers appropriately.
> 
> Add support for detecting, obtaining and configuring PHYs supported
> by a multiport controller. Limit support to multiport controllers
> with up to four ports for now (e.g. as needed for SC8280XP).
> 
> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
> Reviewed-by: Johan Hovold <johan+linaro@...nel.org>
> ---
>  drivers/usb/dwc3/core.c | 251 ++++++++++++++++++++++++++++------------
>  drivers/usb/dwc3/core.h |  14 ++-
>  drivers/usb/dwc3/drd.c  |  15 ++-
>  3 files changed, 193 insertions(+), 87 deletions(-)
> 

<snip>

> @@ -1937,6 +2020,10 @@ static int dwc3_get_num_ports(struct dwc3 *dwc)
>  
>  	iounmap(base);
>  
> +	if (dwc->num_usb2_ports > DWC3_MAX_PORTS ||
> +	    dwc->num_usb3_ports > DWC3_MAX_PORTS)
> +		return -ENOMEM;

This should be -EINVAL.

> +
>  	return 0;
>  }

<snip>

> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 341e4c73cb2e..df2e111aa848 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -33,6 +33,12 @@
>  
>  #include <linux/power_supply.h>
>  
> +/*
> + * Maximum number of ports currently supported for multiport
> + * controllers.

This macro here is being used per USB2 vs USB3 ports rather than USB2 +
USB3, unlike the xHCI MAXPORTS. You can clarify in the comment and
rename the macro to avoid any confusion. You can also create 2 separate
macros for number of USB2 and USB3 ports even if they share the same
value.

As noted[*], we support have different max number of usb2 ports vs usb3
ports. I would suggest splitting the macros.

[*] https://lore.kernel.org/linux-usb/20230801013031.ft3zpoatiyfegmh6@synopsys.com/

> + */
> +#define DWC3_MAX_PORTS 4
> +
> 

But it's not a big issue whether you decided to push a new version or a
create a separate patch for the comments above. Here's my Ack:

Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>

Thanks,
Thinh