Re: [PATCH v7 4/5] usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default

[Bjorn Andersson]

On Thu 28 Jan 22:46 CST 2021, Wesley Cheng wrote:

> In order to take advantage of the TX fifo resizing logic, manually add
> these properties to the DWC3 child node by default.  This will allow
> the DWC3 gadget to resize the TX fifos for the IN endpoints, which
> help with performance.
> 
> Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index d803ee9..4ea6be3 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -564,6 +564,7 @@ static int dwc3_qcom_clk_init(struct dwc3_qcom *qcom, int count)
>  
>  static const struct property_entry dwc3_qcom_acpi_properties[] = {
>  	PROPERTY_ENTRY_STRING("dr_mode", "host"),
> +	PROPERTY_ENTRY_BOOL("tx-fifo-resize"),

I checked the ACPI tables for Lenovo Miix 630, Yoga C630 and Flex 5G and
neither one has this property specified. So while we could just add this
here, it would have to be done in collaboration with the people who
actually define these. And as said before, I believe we want this to
always be enabled.

>  	{}
>  };
>  
> @@ -634,6 +635,7 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev)
>  	struct dwc3_qcom	*qcom = platform_get_drvdata(pdev);
>  	struct device_node	*np = pdev->dev.of_node, *dwc3_np;
>  	struct device		*dev = &pdev->dev;
> +	struct property		*prop;
>  	int			ret;
>  
>  	dwc3_np = of_get_child_by_name(np, "dwc3");
> @@ -642,6 +644,14 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev)
>  		return -ENODEV;
>  	}
>  
> +	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
> +	if (prop) {
> +		prop->name = "tx-fifo-resize";
> +		ret = of_add_property(dwc3_np, prop);

Can't we come up with a way where the platform driver enables this on
the core driver without modifying DT?

Regards,
Bjorn

> +		if (ret < 0)
> +			dev_info(dev, "unable to add tx-fifo-resize prop\n");
> +	}
> +
>  	ret = of_platform_populate(np, NULL, NULL, dev);
>  	if (ret) {
>  		dev_err(dev, "failed to register dwc3 core - %d\n", ret);
> -- 
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>