Hi,
Thinh Nguyen wrote:
> Currently the calculation of max packet size limit for IN endpoints is
> too restrictive. This prevents a matching of a capable hardware endpoint
> during configuration. Below is the minimum recommended HW configuration
> to support a particular endpoint setup from the databook:
>
> For OUT endpoints, the databook recommended the minimum RxFIFO size to
> be at least 3x MaxPacketSize + 3x setup packets size (8 bytes each) +
> clock crossing margin (16 bytes).
>
> For IN endpoints, the databook recommended the minimum TxFIFO size to be
> at least 3x MaxPacketSize for endpoints that support burst. If the
> endpoint doesn't support burst or when the device is operating in USB
> 2.0 mode, a minimum TxFIFO size of 2x MaxPacketSize is recommended.
>
> Base on these recommendations, we can calculate the MaxPacketSize limit
> of each endpoint. This patch revises the IN endpoint MaxPacketSize limit
> and also sets the MaxPacketSize limit for OUT endpoints.
>
> Reference: Databook 3.30a section 3.2.2 and 3.2.3
>
> Signed-off-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
> ---
> Changes in v2 -
> None
>
> drivers/usb/dwc3/core.h | 4 ++++
> drivers/usb/dwc3/gadget.c | 52 +++++++++++++++++++++++++++++++++++++----------
> 2 files changed, 45 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 6a6baadcb697..0f019db5e125 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -309,6 +309,10 @@
> #define DWC3_GTXFIFOSIZ_TXFDEP(n) ((n) & 0xffff)
> #define DWC3_GTXFIFOSIZ_TXFSTADDR(n) ((n) & 0xffff0000)
>
> +/* Global RX Fifo Size Register */
> +#define DWC31_GRXFIFOSIZ_RXFDEP(n) ((n) & 0x7fff) /* DWC_usb31 only */
> +#define DWC3_GRXFIFOSIZ_RXFDEP(n) ((n) & 0xffff)
> +
> /* Global Event Size Registers */
> #define DWC3_GEVNTSIZ_INTMASK BIT(31)
> #define DWC3_GEVNTSIZ_SIZE(n) ((n) & 0xffff)
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 5da266173146..3b3e6a655c6a 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2207,7 +2207,6 @@ static int dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep)
> {
> struct dwc3 *dwc = dep->dwc;
> int mdwidth;
> - int kbytes;
> int size;
>
> mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
> @@ -2223,17 +2222,17 @@ static int dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep)
> /* FIFO Depth is in MDWDITH bytes. Multiply */
> size *= mdwidth;
>
> - kbytes = size / 1024;
> - if (kbytes == 0)
> - kbytes = 1;
> -
> /*
> - * FIFO sizes account an extra MDWIDTH * (kbytes + 1) bytes for
> - * internal overhead. We don't really know how these are used,
> - * but documentation say it exists.
> + * To meet performance requirement, a minimum TxFIFO size of 3x
> + * MaxPacketSize is recommended for endpoints that support burst and a
> + * minimum TxFIFO size of 2x MaxPacketSize for endpoints that don't
> + * support burst. Use those numbers and we can calculate the max packet
> + * limit as below.
> */
> - size -= mdwidth * (kbytes + 1);
> - size /= kbytes;
> + if (dwc->maximum_speed >= USB_SPEED_SUPER)
> + size /= 3;
> + else
> + size /= 2;
>
> usb_ep_set_maxpacket_limit(&dep->endpoint, size);
>
> @@ -2251,8 +2250,39 @@ static int dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep)
> static int dwc3_gadget_init_out_endpoint(struct dwc3_ep *dep)
> {
> struct dwc3 *dwc = dep->dwc;
> + int mdwidth;
> + int size;
> +
> + mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
> +
> + /* MDWIDTH is represented in bits, convert to bytes */
> + mdwidth /= 8;
>
> - usb_ep_set_maxpacket_limit(&dep->endpoint, 1024);
> + /* All OUT endpoints share a single RxFIFO space */
> + size = dwc3_readl(dwc->regs, DWC3_GRXFIFOSIZ(0));
> + if (dwc3_is_usb31(dwc))
> + size = DWC31_GRXFIFOSIZ_RXFDEP(size);
> + else
> + size = DWC3_GRXFIFOSIZ_RXFDEP(size);
> +
> + /* FIFO depth is in MDWDITH bytes */
> + size *= mdwidth;
> +
> + /*
> + * To meet performance requirement, a minimum recommended RxFIFO size
> + * is defined as follow:
> + * RxFIFO size >= (3 x MaxPacketSize) +
> + * (3 x 8 bytes setup packets size) + (16 bytes clock crossing margin)
> + *
> + * Then calculate the max packet limit as below.
> + */
> + size -= (3 * 8) + 16;
> + if (size < 0)
> + size = 0;
> + else
> + size /= 3;
> +
> + usb_ep_set_maxpacket_limit(&dep->endpoint, size);
> dep->endpoint.max_streams = 15;
> dep->endpoint.ops = &dwc3_gadget_ep_ops;
> list_add_tail(&dep->endpoint.ep_list,
Please let me know if these patches are not clear or that they are lost
somewhere. I'll try my best to clarify if anything's not clear.
Thanks,
Thinh
