lkml.org 
[lkml]   [2020]   [May]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC v3 1/3] usb: dwc3: Resize TX FIFOs to meet EP bursting requirements
From
Date


On 5/29/2020 9:28 AM, Jack Pham wrote:
> Hi Wesley,
>
> On Wed, May 27, 2020 at 06:46:01PM -0700, Wesley Cheng 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.
>>
>> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
>> ---
>
> <snip>
>
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 00746c2..9b09528 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 *dwc, struct dwc3_ep *dep)
>
> The 'dep' param should be sufficient; we can just get 'dwc' from
> dep->dwc. That will make it more clear this function operates on each
> endpoint that needs resizing.
>

Hi Jack,

Thanks for the inputs. Sure, I agree with that. Will make the changes
to pass in only the dep.

>> +{
>> + 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);
>
> Use dev_WARN() here and eliminate the WARN_ON(1) below?
>

I think we can just remove the WARN_ON() entirely, and keep the
dev_err(). Printing the callstack might not be really useful in
general, since this would only be called during the EP enable step.


>> + 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;
>> + WARN_ON(1);
>> + 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(dwc, dep);
>> + if (ret)
>> + return ret;
>> +
>> ret = dwc3_gadget_start_config(dep);
>> if (ret)
>> return ret;
>
> Jack
>

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

\
 
 \ /
  Last update: 2020-05-30 08:45    [W:0.054 / U:2.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site