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drivers: usb: xhci: set HID bit in streaming endpoint contexts

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The xHC may commence Host Initiated Data Moves for streaming endpoints -
see USB3.2 spec s8.12.1.4.2.4. However, this behaviour is typically
counterproductive as the submission of UAS URBs in {Status, Data,
Command} order and 1 outstanding IO per stream ID means the device never
enters Move Data after a HIMD for Status or Data stages with the same
stream ID. For OUT transfers this is especially inefficient as the host
will start transmitting multiple bulk packets as a burst, all of which
get NAKed by the device - wasting bandwidth.

Also, some buggy UAS adapters don't properly handle the EP flow control
state this creates - e.g. RTL9210.

Set Host Initiated Data Move Disable to always defer stream selection to
the device. xHC implementations may treat this field as "don't care,
forced to 1" anyway - xHCI 1.2 s4.12.1.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
This commit is contained in:
Jonathan Bell
2024-11-11 10:30:38 +00:00
committed by Dom Cobley
parent 8ac96ec6ff
commit 14f86af818
2 changed files with 10 additions and 0 deletions
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8
drivers/usb/host/xhci-mem.c
View File

@@ -738,6 +738,14 @@ void xhci_setup_streams_ep_input_ctx(struct xhci_hcd *xhci,
ep_ctx->ep_info &= cpu_to_le32(~EP_MAXPSTREAMS_MASK);
ep_ctx->ep_info |= cpu_to_le32(EP_MAXPSTREAMS(max_primary_streams)
| EP_HAS_LSA);
/*
* Set Host Initiated Data Move Disable to always defer stream
* selection to the device. xHC implementations may treat this
* field as "don't care, forced to 1" anyway - xHCI 1.2 s4.12.1.
*/
ep_ctx->ep_info2 |= EP_HID;
ep_ctx->deq = cpu_to_le64(stream_info->ctx_array_dma);
}

2
drivers/usb/host/xhci.h
View File

@@ -465,6 +465,8 @@ struct xhci_ep_ctx {
#define CTX_TO_EP_MAXPSTREAMS(p) (((p) & EP_MAXPSTREAMS_MASK) >> 10)
/* Endpoint is set up with a Linear Stream Array (vs. Secondary Stream Array) */
#define EP_HAS_LSA (1 << 15)
/* Host initiated data move disable in info2 */
#define EP_HID (1 << 7)
/* hosts with LEC=1 use bits 31:24 as ESIT high bits. */
#define CTX_TO_MAX_ESIT_PAYLOAD_HI(p) (((p) >> 24) & 0xff)