Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx> wrote:
> The Realtek wifi 5 devices which support USB 3 are weird: when first
> plugged in, they pretend to be USB 2. The driver needs to send some
> commands to the device, which make it disappear and come back as a
> USB 3 device.
>
> Implement the required commands in rtw88.
>
> When a USB 3 device is plugged into a USB 2 port, rtw88 will try to
> switch it to USB 3 mode only once. The device will disappear and come
> back still in USB 2 mode, of course.
>
> Some people experience heavy interference in the 2.4 GHz band in
> USB 3 mode, so add a module parameter switch_usb_mode with the
> default value 1 to let people disable the switching.
>
> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@xxxxxxxxx>
> ---
> A later patch will add the function rtw_usb_switch_mode_old() for the
> older chips RTL8812AU and RTL8814AU.
[...]
> diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
> index a55ca5a24227..a59e52a0da10 100644
> --- a/drivers/net/wireless/realtek/rtw88/usb.c
> +++ b/drivers/net/wireless/realtek/rtw88/usb.c
> @@ -14,6 +14,11 @@
> #include "ps.h"
> #include "usb.h"
>
> +static bool rtw_switch_usb_mode = true;
> +module_param_named(switch_usb_mode, rtw_switch_usb_mode, bool, 0644);
> +MODULE_PARM_DESC(switch_usb_mode,
> + "Set to Y to switch to USB 3 mode (default: Y)");
> +
I feel we should say "Set to N to disable switching USB 3 mode to avoid
potential interference in the 2.4 GHz" like your commit message. That could
be helpful to users.
> #define RTW_USB_MAX_RXQ_LEN 512
>
> struct rtw_usb_txcb {
[...]
> @@ -896,6 +972,14 @@ int rtw_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
> goto err_destroy_rxwq;
> }
>
> + ret = rtw_usb_switch_mode(rtwdev);
> + if (ret) {
> + /* Not a fail, but we do need to skip rtw_register_hw. */
> + rtw_info(rtwdev, "switching to USB 3 mode\n");
All logs in this patches should be rtw_dbg(), because these messages are not
important to users.
> + ret = 0;
> + goto err_destroy_rxwq;
> + }
> +
> ret = rtw_register_hw(rtwdev, rtwdev->hw);
> if (ret) {
> rtw_err(rtwdev, "failed to register hw\n");
> --
> 2.45.1
