[PATCH v3] usb: cdns3: gadget.c: Set fast access bit

[Marek Vasut]

On 4/24/24 9:39 AM, Ravi Gunasekaran wrote:
> From: Aswath Govindraju <a-govindraju at ti.com>
> 
> When the device port is in a low power state [U3/L2/Not Connected],
> accesses to usb device registers may take a long time. This could lead to
> potential core hang when the controller registers are accessed after the
> port is disabled by setting DEVDS field. Setting the fast register access
> bit ensures that the PHY clock is keeping up in active state.
> 
> Therefore, set fast access bit to ensure the accesses to device registers
> are quick even in low power states.
> 
> commit b5148d946f45 ("usb: cdns3: gadget: set fast access bit") in the
> upstream kernel is taken as reference.
> 
> Signed-off-by: Aswath Govindraju <a-govindraju at ti.com>
> Signed-off-by: Ravi Gunasekaran <r-gunasekaran at ti.com>
> Reviewed-by: Roger Quadros <rogerq at kernel.org>
> Reviewed-by: Marek Vasut <marex at denx.de>
> ---
> Changes since v2:
> ----------------
> * Updated the commit description with reference to upstream kernel commit
> * Picked up Marek's Reviewed-by tag from v2
> 
> Changes since v1:
> -----------------
> * Rebased to tip of -next
> * Added Reviewed-by tag
> 
> v2: https://lore.kernel.org/all/20240423082420.32336-1-r-gunasekaran@ti.com/
> v1: https://lore.kernel.org/u-boot/20230505121353.23486-1-r-gunasekaran@ti.com/
> 
>   drivers/usb/cdns3/gadget.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
> index 7aa0c6b2be..d11175dc5b 100644
> --- a/drivers/usb/cdns3/gadget.c
> +++ b/drivers/usb/cdns3/gadget.c
> @@ -2325,6 +2325,9 @@ static void cdns3_gadget_config(struct cdns3_device *priv_dev)
>   	writel(USB_IEN_INIT, &regs->usb_ien);
>   	writel(USB_CONF_CLK2OFFDS | USB_CONF_L1DS, &regs->usb_conf);
>   
> +	/* Set the Fast access bit */
> +	writel(PUSB_PWR_FST_REG_ACCESS, &priv_dev->regs->usb_pwr);
> +
>   	cdns3_configure_dmult(priv_dev, NULL);
>   
>   	cdns3_gadget_pullup(&priv_dev->gadget, 1);
> @@ -2383,6 +2386,7 @@ static int cdns3_gadget_udc_stop(struct usb_gadget *gadget)
>   
>   	/* disable interrupt for device */
>   	writel(0, &priv_dev->regs->usb_ien);
> +	writel(0, &priv_dev->regs->usb_pwr);
>   	writel(USB_CONF_DEVDS, &priv_dev->regs->usb_conf);
>   
>   	return ret;
> 
> base-commit: bc39e06778168a34bb4e0a34fbee4edbde4414d8

Since this is gadget stuff, +CC Mattijs , that should go through their tree.

Thanks!