From: Wesley Cheng quic_wcheng@quicinc.com
commit 9c1e916960c1192e746bf615e4dae25423473a64 upstream.
The current logic to assign the max packet limit for IN endpoints attempts to take the default HW value and apply the optimal endpoint settings based on it. However, if the default value reports a TxFIFO size large enough for only one max packet, it will divide the value and assign a smaller ep max packet limit.
For example, if the default TxFIFO size fits 1024B, current logic will assign 1024/3 = 341B to ep max packet size. If function drivers attempt to request for an endpoint with a wMaxPacketSize of 1024B (SS BULK max packet size) then it will fail, as the gadget is unable to find an endpoint which can fit the requested size.
Functionally, if the TxFIFO has enough space to fit one max packet, it will be sufficient, at least when initializing the endpoints.
Fixes: d94ea5319813 ("usb: dwc3: gadget: Properly set maxpacket limit") Cc: stable stable@kernel.org Signed-off-by: Wesley Cheng quic_wcheng@quicinc.com Link: https://lore.kernel.org/r/20220523213948.22142-1-quic_wcheng@quicinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/dwc3/gadget.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-)
--- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -2984,6 +2984,7 @@ static int dwc3_gadget_init_in_endpoint( struct dwc3 *dwc = dep->dwc; u32 mdwidth; int size; + int maxpacket;
mdwidth = dwc3_mdwidth(dwc);
@@ -2996,21 +2997,24 @@ static int dwc3_gadget_init_in_endpoint( else size = DWC31_GTXFIFOSIZ_TXFDEP(size);
- /* FIFO Depth is in MDWDITH bytes. Multiply */ - size *= mdwidth; - /* - * 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. + * maxpacket size is determined as part of the following, after assuming + * a mult value of one maxpacket: + * DWC3 revision 280A and prior: + * fifo_size = mult * (max_packet / mdwidth) + 1; + * maxpacket = mdwidth * (fifo_size - 1); + * + * DWC3 revision 290A and onwards: + * fifo_size = mult * ((max_packet + mdwidth)/mdwidth + 1) + 1 + * maxpacket = mdwidth * ((fifo_size - 1) - 1) - mdwidth; */ - if (dwc->maximum_speed >= USB_SPEED_SUPER) - size /= 3; + if (DWC3_VER_IS_PRIOR(DWC3, 290A)) + maxpacket = mdwidth * (size - 1); else - size /= 2; + maxpacket = mdwidth * ((size - 1) - 1) - mdwidth;
+ /* Functionally, space for one max packet is sufficient */ + size = min_t(int, maxpacket, 1024); usb_ep_set_maxpacket_limit(&dep->endpoint, size);
dep->endpoint.max_streams = 16;