Re: [PATCH v36 06/31] usb: dwc3: Specify maximum number of XHCI interrupters

[Puma Hsu]

On Wed, Mar 19, 2025 at 8:53 AM Wesley Cheng <quic_wcheng@xxxxxxxxxxx> wrote:
>
> Allow for the DWC3 host driver to pass along XHCI property that defines
> how many interrupters to allocate.  This is in relation for the number of
> event rings that can be potentially used by other processors within the
> system.
>
> Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
> Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>

Tested-by: Puma Hsu <pumahsu@xxxxxxxxxx>

> ---
>  drivers/usb/dwc3/core.c | 12 ++++++++++++
>  drivers/usb/dwc3/core.h |  2 ++
>  drivers/usb/dwc3/host.c |  3 +++
>  3 files changed, 17 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 66a08b527165..17ae5c13fe36 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1699,6 +1699,7 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>         u8                      tx_thr_num_pkt_prd = 0;
>         u8                      tx_max_burst_prd = 0;
>         u8                      tx_fifo_resize_max_num;
> +       u16                     num_hc_interrupters;
>
>         /* default to highest possible threshold */
>         lpm_nyet_threshold = 0xf;
> @@ -1719,6 +1720,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>          */
>         tx_fifo_resize_max_num = 6;
>
> +       /* default to a single XHCI interrupter */
> +       num_hc_interrupters = 1;
> +
>         dwc->maximum_speed = usb_get_maximum_speed(dev);
>         dwc->max_ssp_rate = usb_get_maximum_ssp_rate(dev);
>         dwc->dr_mode = usb_get_dr_mode(dev);
> @@ -1765,6 +1769,12 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>                                 &tx_thr_num_pkt_prd);
>         device_property_read_u8(dev, "snps,tx-max-burst-prd",
>                                 &tx_max_burst_prd);
> +       device_property_read_u16(dev, "num-hc-interrupters",
> +                                &num_hc_interrupters);
> +       /* DWC3 core allowed to have a max of 8 interrupters */
> +       if (num_hc_interrupters > 8)
> +               num_hc_interrupters = 8;
> +
>         dwc->do_fifo_resize = device_property_read_bool(dev,
>                                                         "tx-fifo-resize");
>         if (dwc->do_fifo_resize)
> @@ -1851,6 +1861,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>         dwc->tx_max_burst_prd = tx_max_burst_prd;
>
>         dwc->tx_fifo_resize_max_num = tx_fifo_resize_max_num;
> +
> +       dwc->num_hc_interrupters = num_hc_interrupters;
>  }
>
>  /* check whether the core supports IMOD */
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index aaa39e663f60..fbe83914d9f9 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1083,6 +1083,7 @@ struct dwc3_scratchpad_array {
>   * @tx_max_burst_prd: max periodic ESS transmit burst size
>   * @tx_fifo_resize_max_num: max number of fifos allocated during txfifo resize
>   * @clear_stall_protocol: endpoint number that requires a delayed status phase
> + * @num_hc_interrupters: number of host controller interrupters
>   * @hsphy_interface: "utmi" or "ulpi"
>   * @connected: true when we're connected to a host, false otherwise
>   * @softconnect: true when gadget connect is called, false when disconnect runs
> @@ -1330,6 +1331,7 @@ struct dwc3 {
>         u8                      tx_max_burst_prd;
>         u8                      tx_fifo_resize_max_num;
>         u8                      clear_stall_protocol;
> +       u16                     num_hc_interrupters;
>
>         const char              *hsphy_interface;
>
> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> index b48e108fc8fe..1c513bf8002e 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -182,6 +182,9 @@ int dwc3_host_init(struct dwc3 *dwc)
>         if (DWC3_VER_IS_WITHIN(DWC3, ANY, 300A))
>                 props[prop_idx++] = PROPERTY_ENTRY_BOOL("quirk-broken-port-ped");
>
> +       props[prop_idx++] = PROPERTY_ENTRY_U16("num-hc-interrupters",
> +                                              dwc->num_hc_interrupters);
> +
>         if (prop_idx) {
>                 ret = device_create_managed_software_node(&xhci->dev, props, NULL);
>                 if (ret) {
>