Hi Selvarasu,
On 11/6/2024 12:29 PM, Selvarasu Ganesan wrote:
On 10/17/2024 12:14 PM, Akash Kumar wrote:
The current logic is rigid, setting num_fifos to fixed values.
3 for any maxburst greater than 1.
tx_fifo_resize_max_num for maxburst greater than 6.
Additionally, it did not differentiate much between bulk and
isochronous transfers, applying similar logic to both.
The updated logic is more flexible and specifically designed to meet
the unique requirements of both bulk and isochronous transfers. We
have made every effort to satisfy all needs and requirements, verified
on our specific platform and application.
Bulk Transfers: Ensures that num_fifos is optimized by considering both
the maxburst and DT property "tx-fifo-max-num" for super speed and
above. For high-speed and below bulk endpoints, a 2K TxFIFO allocation
is used to meet efficient data transfer needs, considering
FIFO-constrained platforms.
Isochronous Transfers: Ensures that num_fifos is sufficient by
considering the maximum packet multiplier for HS and below and maxburst
for Super-speed and above eps, along with a constraint with the DT
property "tx-fifo-max-num".
This change aims to optimize the allocation of Tx FIFOs for both bulk
and isochronous endpoints, potentially improving data transfer efficiency
and overall performance. It also enhances support for all use cases,
which can be tweaked with DT parameters and the endpoint’s maxburst and
maxpacket. This structured approach ensures that the appropriate number
of FIFOs is allocated based on the endpoint type and USB speed.
Signed-off-by: Akash Kumar <quic_akakum@xxxxxxxxxxx>
---
Changes for v7:
fixed indentations for if checks.
Changes for v6:
The code has been refactored to replace multiple if checks with a
switch-case structure based on the USB speed. This change improves
readability and maintainability by clearly defining behavior for
different USB speeds. This structured approach ensures that the
appropriate number of FIFOs is allocated based on the endpoint
type and USB speed.
Changes for v5:
Update Calculation for HS and below bulk and isoc eps based on
suggestion and fixed at 2k for bulk eps considering fifo constrained
platforms.
Changes for v4:
Updated commit message as per review comments to clarify that it has
been tested on specific platforms only and tried best to match all
expectations.
Changes for v3:
Redefine logic for resizing tx fifos,added check based on operating
speed and used maxp for HS and maxburst for SS and defined max allocation
based on dt property.
Changes for v2:
Redefine logic for resizing tx fifos, handled fifo based on minimum of
maxp and maxburts.
Changes for v1:
Added additional condition to allocate tx fifo for hs isoc eps, keeping
the other resize logic same
---
drivers/usb/dwc3/gadget.c | 33 ++++++++++++++++++++++++---------
1 file changed, 24 insertions(+), 9 deletions(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 10178e5eda5a..af3d5b2f7b67 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -771,15 +771,30 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
- if ((dep->endpoint.maxburst > 1 &&
- usb_endpoint_xfer_bulk(dep->endpoint.desc)) ||
- usb_endpoint_xfer_isoc(dep->endpoint.desc))
- num_fifos = 3;
-
- if (dep->endpoint.maxburst > 6 &&
- (usb_endpoint_xfer_bulk(dep->endpoint.desc) ||
- usb_endpoint_xfer_isoc(dep->endpoint.desc)) && DWC3_IP_IS(DWC31))
- num_fifos = dwc->tx_fifo_resize_max_num;
+ switch (dwc->gadget->speed) {
+ case USB_SPEED_SUPER_PLUS:
+ case USB_SPEED_SUPER:
+ if (usb_endpoint_xfer_bulk(dep->endpoint.desc) ||
+ usb_endpoint_xfer_isoc(dep->endpoint.desc))
+ num_fifos = min_t(unsigned int,
+ dep->endpoint.maxburst,
+ dwc->tx_fifo_resize_max_num);
+ break;
+ case USB_SPEED_HIGH:
+ if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
+ num_fifos = min_t(unsigned int,
+ usb_endpoint_maxp_mult(dep->endpoint.desc) + 1,
Hi Akash,
We are currently working on enabling UVC functionality on supports USB
HS and below speeds with using a single port RAM configuration.
In order to better understand the logic behind resizing HS ISO transfers
when using a streaming packet size of 3072 in the UVC use case, we would
like to know if there is a specific reason for using
(usb_endpoint_maxp_mult(dep->endpoint.desc) + 1) to determine the number
of FIFOs. This calculation could result in having 4 FIFOs instead of 3,
even though 3 FIFOs should be sufficient for handling the 3072 streaming
packet size. In our specific use case, this could potentially lead to an
insufficient RAM issue, as we are limited by the amount of RAM available
in the single port RAM configuration and supports upto HS-speed.
the reason for using maxp +1 is to use higher fifo size to support 1080
mjpeg uvc streaming in HS or any uvc instances using less maxpacket like
512 for UVC usecase,
can use 2k fifo. For any fifo constraint environment we have suggested
to use dt property "tx-fifo-max-num" which can set accordingly, for your
case you can set to
2 or 3.
+ dwc->tx_fifo_resize_max_num);
+ break;
+ }
+ fallthrough;
+ case USB_SPEED_FULL:
+ if (usb_endpoint_xfer_bulk(dep->endpoint.desc))
+ num_fifos = 2;
And we need to understand on above logic as well. Why using num_fifos =2
for bulk transfer for HS and FULL speed?. It can ending with 2k (4 *
Maxpacktsize).
As per our understanding (2 x Maxpacketsize) is sufficient for bulk. Its
means that num_fifos = 1 is sufficient for bulk. As i mentioned above
this could potentially lead to an insufficient RAM issue in our platform.
2k Fifo is useful for bulk eps incase of multiple bulk operations
simultaneously to avoid buffer underrrun issues,
Like i shared above DT property can be used to limit max fifo per ep to
support platforms with less RAM size.
+ break;
+ default:
+ break;
+ }
/* FIFO size for a single buffer */
fifo = dwc3_gadget_calc_tx_fifo_size(dwc, 1);
Thanks,
Akash
