Re: [PATCH v6] usb: musb: dsps: implement vbus_status and set_vbus platform ops

[Bin Liu]

On Fri, Jul 17, 2026 at 07:44:53PM +0000, Lucas Martins Alves wrote:
> From: Lucas Martins Alves <lucas.alves@xxxxxxxxxxxxxx>
> 
> The DSPS glue layer (used on TI AM335x SoCs) was missing implementations
> for the vbus_status and set_vbus platform ops defined in struct
> musb_platform_ops.
> 
> Add dsps_musb_vbus_status() to report VBUS presence by reading the VBUS
> field of MUSB_DEVCTL, and dsps_musb_set_vbus() to drive the SESSION bit
> on MUSB_DEVCTL, enabling or disabling the USB session.
> 
> Register both callbacks in dsps_ops to allow the MUSB core to control
> VBUS on AM335x-based platforms. This enables the USB core to perform a
> VBUS power cycle as a recovery mechanism when a USB error condition is
> detected, and also allows userspace to control VBUS state via the
> standard USB sysfs interface.

What you need is musb_softconnect_write() in musb_debugfs.c
-Bin.

> 
> Signed-off-by: Lucas Martins Alves <lucas.alves@xxxxxxxxxxxxxx>
> ---
> v1 -> v2:
> - Remove the unintended musb context changes introduced in the first patch.
> v2 -> v3:
> - Corrects the text in the patch description.
> v3 -> v4:
> - Remove improperly attached patch file.
> v4 -> v5:
> - Re-send patch v4 in a new thread.
> v5 -> v6:
> - Corrects the history of the patch that was removed in v5.
> ---
>  drivers/usb/musb/musb_dsps.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
> index e3935f18dd56..efd1f0dbb926 100644
> --- a/drivers/usb/musb/musb_dsps.c
> +++ b/drivers/usb/musb/musb_dsps.c
> @@ -618,6 +618,29 @@ static int dsps_musb_recover(struct musb *musb)
>  	return session_restart ? 0 : -EPIPE;
>  }
>  
> +static int dsps_musb_vbus_status(struct musb *musb)
> +{
> +	u8 devctl = musb_readb(musb->mregs, MUSB_DEVCTL);
> +
> +	return (devctl & MUSB_DEVCTL_VBUS) == MUSB_DEVCTL_VBUS;
> +}
> +
> +static void dsps_musb_set_vbus(struct musb *musb, int is_on)
> +{
> +	u8 devctl;
> +
> +	devctl = musb_readb(musb->mregs, MUSB_DEVCTL);
> +
> +	if (is_on) {
> +		devctl |= MUSB_DEVCTL_SESSION;
> +	} else {
> +		musb_root_disconnect(musb);
> +		devctl &= ~MUSB_DEVCTL_SESSION;
> +	}
> +
> +	musb_writeb(musb->mregs, MUSB_DEVCTL, devctl);
> +}
> +
>  /* Similar to am35x, dm81xx support only 32-bit read operation */
>  static void dsps_read_fifo32(struct musb_hw_ep *hw_ep, u16 len, u8 *dst)
>  {
> @@ -702,6 +725,8 @@ static struct musb_platform_ops dsps_ops = {
>  
>  	.set_mode	= dsps_musb_set_mode,
>  	.recover	= dsps_musb_recover,
> +	.vbus_status	= dsps_musb_vbus_status,
> +	.set_vbus	= dsps_musb_set_vbus,
>  	.clear_ep_rxintr = dsps_musb_clear_ep_rxintr,
>  };
>  
> -- 
> 2.53.0
>