[PATCH 17/36] usb: gadget: f_tcm: Increase bMaxBurst

Thinh Nguyen
2022-07-06T23:36:13Z

Currently the default bMaxBurst is 0. Set default bMaxBurst to 15 (i.e.
16 bursts) to Data IN and OUT endpoints to improve performance. It
should be fine for a controller that supports less than 16 bursts. It
should be able to negotiate properly with the host at packet level for
the end of burst.

If the controller can't handle a burst of 16, and high performance isn't
important, the user can use BOT protocol from mass_storage gadget driver
instead.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
drivers/usb/gadget/function/f_tcm.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c
index 8e17ac831be0..270ec631481d 100644
--- a/drivers/usb/gadget/function/f_tcm.c
+++ b/drivers/usb/gadget/function/f_tcm.c
@@ -1774,7 +1774,7 @@ static struct usb_endpoint_descriptor uasp_ss_bi_desc = {
static struct usb_ss_ep_comp_descriptor uasp_bi_ep_comp_desc = {
.bLength = sizeof(uasp_bi_ep_comp_desc),
.bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
- .bMaxBurst = 0,
+ .bMaxBurst = 15,
.bmAttributes = UASP_SS_EP_COMP_LOG_STREAMS,
.wBytesPerInterval = 0,
};
@@ -1782,7 +1782,7 @@ static struct usb_ss_ep_comp_descriptor uasp_bi_ep_comp_desc = {
static struct usb_ss_ep_comp_descriptor bot_bi_ep_comp_desc = {
.bLength = sizeof(bot_bi_ep_comp_desc),
.bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
- .bMaxBurst = 0,
+ .bMaxBurst = 15,
};

static struct usb_endpoint_descriptor uasp_bo_desc = {
@@ -1817,12 +1817,14 @@ static struct usb_endpoint_descriptor uasp_ss_bo_desc = {
static struct usb_ss_ep_comp_descriptor uasp_bo_ep_comp_desc = {
.bLength = sizeof(uasp_bo_ep_comp_desc),
.bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+ .bMaxBurst = 15,
.bmAttributes = UASP_SS_EP_COMP_LOG_STREAMS,
};

static struct usb_ss_ep_comp_descriptor bot_bo_ep_comp_desc = {
.bLength = sizeof(bot_bo_ep_comp_desc),
.bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
+ .bMaxBurst = 15,
};

static struct usb_endpoint_descriptor uasp_status_desc = {
--
2.28.0