Re: [RFC v4 1/3] usb: dwc3: Resize TX FIFOs to meet EP bursting requirements

Peter Chen
2020-08-12T02:22:33Z

On Wed, Jun 24, 2020 at 10:31 AM Wesley Cheng <wcheng@codeaurora.org> wrote:
>
> Some devices have USB compositions which may require multiple endpoints
> that support EP bursting. HW defined TX FIFO sizes may not always be
> sufficient for these compositions. By utilizing flexible TX FIFO
> allocation, this allows for endpoints to request the required FIFO depth to
> achieve higher bandwidth. With some higher bMaxBurst configurations, using
> a larger TX FIFO size results in better TX throughput.
>
> Ensure that one TX FIFO is reserved for every IN endpoint. This allows for
> the FIFO logic to prevent running out of FIFO space.
>

You may do this for only allocated endpoints, but you need override
default .match_ep
API. See cdns3/gadget.c and cdns3/ep0.c as an example.

Peter

> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
> ---
> drivers/usb/dwc3/core.c | 2 +
> drivers/usb/dwc3/core.h | 8 +++
> drivers/usb/dwc3/ep0.c | 37 +++++++++++-
> drivers/usb/dwc3/gadget.c | 115 ++++++++++++++++++++++++++++++++++++++
> 4 files changed, 161 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index edc17155cb2b..cca555493929 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1304,6 +1304,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> &tx_thr_num_pkt_prd);
> device_property_read_u8(dev, "snps,tx-max-burst-prd",
> &tx_max_burst_prd);
> + dwc->needs_fifo_resize = device_property_read_bool(dev,
> + "tx-fifo-resize");
>
> dwc->disable_scramble_quirk = device_property_read_bool(dev,
> "snps,disable_scramble_quirk");
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 4c171a8e215f..ce0bf288b6ac 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -675,6 +675,7 @@ struct dwc3_event_buffer {
> * isochronous START TRANSFER command failure workaround
> * @start_cmd_status: the status of testing START TRANSFER command with
> * combo_num = 'b00
> + * @fifo_depth: allocated TXFIFO depth
> */
> struct dwc3_ep {
> struct usb_ep endpoint;
> @@ -727,6 +728,7 @@ struct dwc3_ep {
> /* For isochronous START TRANSFER workaround only */
> u8 combo_num;
> int start_cmd_status;
> + int fifo_depth;
> };
>
> enum dwc3_phy {
> @@ -1004,6 +1006,7 @@ struct dwc3_scratchpad_array {
> * 1 - utmi_l1_suspend_n
> * @is_fpga: true when we are using the FPGA board
> * @pending_events: true when we have pending IRQs to be handled
> + * @needs_fifo_resize: not all users might want fifo resizing, flag it
> * @pullups_connected: true when Run/Stop bit is set
> * @setup_packet_pending: true when there's a Setup Packet in FIFO. Workaround
> * @three_stage_setup: set if we perform a three phase setup
> @@ -1044,6 +1047,8 @@ struct dwc3_scratchpad_array {
> * @dis_metastability_quirk: set to disable metastability quirk.
> * @imod_interval: set the interrupt moderation interval in 250ns
> * increments or 0 to disable.
> + * @last_fifo_depth: total TXFIFO depth of all enabled USB IN/INT endpoints
> + * @num_ep_resized: the number of TX FIFOs that have already been resized
> */
> struct dwc3 {
> struct work_struct drd_work;
> @@ -1204,6 +1209,7 @@ struct dwc3 {
> unsigned is_utmi_l1_suspend:1;
> unsigned is_fpga:1;
> unsigned pending_events:1;
> + unsigned needs_fifo_resize:1;
> unsigned pullups_connected:1;
> unsigned setup_packet_pending:1;
> unsigned three_stage_setup:1;
> @@ -1236,6 +1242,8 @@ struct dwc3 {
> unsigned dis_metastability_quirk:1;
>
> u16 imod_interval;
> + int last_fifo_depth;
> + int num_ep_resized;
> };
>
> #define INCRX_BURST_MODE 0
> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> index 6dee4dabc0a4..76db9b530861 100644
> --- a/drivers/usb/dwc3/ep0.c
> +++ b/drivers/usb/dwc3/ep0.c
> @@ -601,8 +601,9 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
> {
> enum usb_device_state state = dwc->gadget.state;
> u32 cfg;
> - int ret;
> + int ret, num, size;
> u32 reg;
> + struct dwc3_ep *dep;
>
> cfg = le16_to_cpu(ctrl->wValue);
>
> @@ -611,6 +612,40 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
> return -EINVAL;
>
> case USB_STATE_ADDRESS:
> + /*
> + * If tx-fifo-resize flag is not set for the controller, then
> + * do not clear existing allocated TXFIFO since we do not
> + * allocate it again in dwc3_gadget_resize_tx_fifos
> + */
> + if (dwc->needs_fifo_resize) {
> + /* Read ep0IN related TXFIFO size */
> + dep = dwc->eps[1];
> + size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
> + if (dwc3_is_usb31(dwc))
> + dep->fifo_depth = DWC31_GTXFIFOSIZ_TXFDEP(size);
> + else
> + dep->fifo_depth = DWC3_GTXFIFOSIZ_TXFDEP(size);
> +
> + dwc->last_fifo_depth = dep->fifo_depth;
> + /* Clear existing TXFIFO for all IN eps except ep0 */
> + for (num = 3; num < min_t(int, dwc->num_eps,
> + DWC3_ENDPOINTS_NUM); num += 2) {
> + dep = dwc->eps[num];
> + /* Don't change TXFRAMNUM on usb31 version */
> + size = dwc3_is_usb31(dwc) ?
> + dwc3_readl(dwc->regs,
> + DWC3_GTXFIFOSIZ(num >> 1)) &
> + DWC31_GTXFIFOSIZ_TXFRAMNUM :
> + 0;
> +
> + dwc3_writel(dwc->regs,
> + DWC3_GTXFIFOSIZ(num >> 1),
> + size);
> + dep->fifo_depth = 0;
> + }
> + dwc->num_ep_resized = 0;
> + }
> +
> ret = dwc3_ep0_delegate_req(dwc, ctrl);
> /* if the cfg matches and the cfg is non zero */
> if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 00746c2848c0..777badf3e85d 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -540,6 +540,117 @@ static int dwc3_gadget_start_config(struct dwc3_ep *dep)
> return 0;
> }
>
> +/*
> + * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
> + * @dwc: pointer to our context structure
> + *
> + * This function will a best effort FIFO allocation in order
> + * to improve FIFO usage and throughput, while still allowing
> + * us to enable as many endpoints as possible.
> + *
> + * Keep in mind that this operation will be highly dependent
> + * on the configured size for RAM1 - which contains TxFifo -,
> + * the amount of endpoints enabled on coreConsultant tool, and
> + * the width of the Master Bus.
> + *
> + * In general, FIFO depths are represented with the following equation:
> + *
> + * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1
> + *
> + * Conversions can be done to the equation to derive the number of packets that
> + * will fit to a particular FIFO size value.
> + */
> +static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
> +{
> + struct dwc3 *dwc = dep->dwc;
> + int ram1_depth, mdwidth, fifo_0_start, tmp, num_in_ep;
> + int min_depth, remaining, fifo_size, mult = 1, fifo, max_packet = 1024;
> +
> + if (!dwc->needs_fifo_resize)
> + return 0;
> +
> + /* resize IN endpoints except ep0 */
> + if (!usb_endpoint_dir_in(dep->endpoint.desc) || dep->number <= 1)
> + return 0;
> +
> + /* Don't resize already resized IN endpoint */
> + if (dep->fifo_depth)
> + return 0;
> +
> + ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
> + mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
> + /* MDWIDTH is represented in bits, we need it in bytes */
> + mdwidth >>= 3;
> +
> + if (((dep->endpoint.maxburst > 1) &&
> + usb_endpoint_xfer_bulk(dep->endpoint.desc))
> + || usb_endpoint_xfer_isoc(dep->endpoint.desc))
> + mult = 3;
> +
> + if ((dep->endpoint.maxburst > 6) &&
> + usb_endpoint_xfer_bulk(dep->endpoint.desc)
> + && dwc3_is_usb31(dwc))
> + mult = 6;
> +
> + /* FIFO size for a single buffer */
> + fifo = (max_packet + mdwidth)/mdwidth;
> + fifo++;
> +
> + /* Calculate the number of remaining EPs w/o any FIFO */
> + num_in_ep = dwc->num_eps/2;
> + num_in_ep -= dwc->num_ep_resized;
> + /* Ignore EP0 IN */
> + num_in_ep--;
> +
> + /* Reserve at least one FIFO for the number of IN EPs */
> + min_depth = num_in_ep * (fifo+1);
> + remaining = ram1_depth - min_depth - dwc->last_fifo_depth;
> +
> + /* We've already reserved 1 FIFO per EP, so check what we can fit in
> + * addition to it. If there is not enough remaining space, allocate
> + * all the remaining space to the EP.
> + */
> + fifo_size = (mult-1) * fifo;
> + if (remaining < fifo_size) {
> + if (remaining > 0)
> + fifo_size = remaining;
> + else
> + fifo_size = 0;
> + }
> +
> + fifo_size += fifo;
> + fifo_size++;
> + dep->fifo_depth = fifo_size;
> +
> + /* Check if TXFIFOs start at non-zero addr */
> + tmp = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
> + fifo_0_start = DWC3_GTXFIFOSIZ_TXFSTADDR(tmp);
> +
> + fifo_size |= (fifo_0_start + (dwc->last_fifo_depth << 16));
> + if (dwc3_is_usb31(dwc))
> + dwc->last_fifo_depth += DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
> + else
> + dwc->last_fifo_depth += DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);
> +
> + /* Check fifo size allocation doesn't exceed available RAM size. */
> + if (dwc->last_fifo_depth >= ram1_depth) {
> + dev_err(dwc->dev, "Fifosize(%d) > RAM size(%d) %s depth:%d\n",
> + (dwc->last_fifo_depth * mdwidth), ram1_depth,
> + dep->endpoint.name, fifo_size);
> + if (dwc3_is_usb31(dwc))
> + fifo_size = DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);
> + else
> + fifo_size = DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);
> + dwc->last_fifo_depth -= fifo_size;
> + dep->fifo_depth = 0;
> + return -ENOMEM;
> + }
> +
> + dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1), fifo_size);
> + dwc->num_ep_resized++;
> + return 0;
> +}
> +
> static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
> {
> const struct usb_ss_ep_comp_descriptor *comp_desc;
> @@ -620,6 +731,10 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
> int ret;
>
> if (!(dep->flags & DWC3_EP_ENABLED)) {
> + ret = dwc3_gadget_resize_tx_fifos(dep);
> + if (ret)
> + return ret;
> +
> ret = dwc3_gadget_start_config(dep);
> if (ret)
> return ret;
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>