Re: [PATCH v2] usb: gadget: cdns3: Fix cdns3_ep_config() by setting ep.maxpacket

[Mattijs Korpershoek <mkorpershoek@baylibre.com>]

Hi Siddharth,

Thank you for the patch.

On lun., oct. 07, 2024 at 17:49, Siddharth Vadapalli <s-vadapalli@ti.com> wrote:

> The function cdns3_ep_config() calculates the maximum packet size based
> on the Endpoint Type and the Gadget Speed and stores it in the variable
> "max_packet_size". This value is then programmed in the USB Controller
> for the corresponding Endpoint. This may result in a mismatch between
> the maximum packet size programmed in the USB controller and the maximum
> packet size seen by the UDC Core via "maxpacket" member of "struct usb_ep".
> Additionally, since TD_SIZE is calculated in cdns3_ep_run_transfer() on the
> basis of the maximum packet size stored in the "maxpacket" member of
> "struct usb_ep", it may lead to an incorrect value of TD_SIZE when compared
> with what the USB controller actually expects (max_packet_size).
>
> Fix this.
>
> Fixes: 7e91f6ccdc84 ("usb: Add Cadence USB3 host and gadget driver")
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

> ---
>
> Hello,
>
> This patch is based on commit
> dd4d130c8e clk: renesas: rcar-gen3: Fix SSCG caching replacement with MDSEL/PE caching
> of the master branch of U-Boot.
>
> v1:
> https://patchwork.ozlabs.org/project/uboot/patch/20241007104239.1624430-1-s-vadapalli@ti.com/
> Changes since v1:
> - Based on Roger's feedback at:
>   https://patchwork.ozlabs.org/project/uboot/patch/20241007104239.1624430-1-s-vadapalli@ti.com/#3389960
>   rather than using usb_ep_set_maxpacket_limit() which changes
>   "maxpacket_limit" in addition to "maxpacket", only update the "maxpacket"
>   member of usb_ep.
>
> Regards,
> Siddharth.
>
>  drivers/usb/cdns3/gadget.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
> index ac7e469469..a30c40ef80 100644
> --- a/drivers/usb/cdns3/gadget.c
> +++ b/drivers/usb/cdns3/gadget.c
> @@ -1637,6 +1637,14 @@ void cdns3_ep_config(struct cdns3_endpoint *priv_ep)
>  	else
>  		priv_ep->trb_burst_size = 16;
>  
> +	/*
> +	 * The Endpoint is configured to handle a maximum packet size of
> +	 * max_packet_size. Hence, set priv_ep->endpoint.maxpacket to
> +	 * max_packet_size. This is necessary to ensure that the TD_SIZE
> +	 * is calculated correctly in cdns3_ep_run_transfer().
> +	 */
> +	priv_ep->endpoint.maxpacket = max_packet_size;
> +
>  	ret = cdns3_ep_onchip_buffer_reserve(priv_dev, buffering + 1,
>  					     !!priv_ep->dir);
>  	if (ret) {
> -- 
> 2.40.1