From: Ben Hoff <hoff.benjamin.k@xxxxxxxxx>
This patch enhances the HID gadget driver to support dynamic configuration
of the interrupt polling interval (bInterval) via configfs. A new
‘interval’ attribute is exposed under each HID function’s configfs
directory, and any write to it will adjust the poll rate for all endpoints
without requiring a rebuild.
When the attribute has never been written, legacy defaults are preserved:
• Full-Speed (FS) endpoints (IN & OUT) poll every 10 ms
• High-Speed (HS) endpoints (IN & OUT) poll every 4 micro-frames
(~1 ms)
To implement this cleanly:
• Add two new fields to f_hid_opts and f_hidg:
– unsigned char interval
– bool interval_user_set
• Introduce dedicated f_hid_opts_interval_show/store functions.
The store routine parses into an unsigned int, bounds‐checks,
assigns to opts->interval, and sets opts->interval_user_set = true.
• Initialize opts->interval = 4 and opts->interval_user_set = false in
hidg_alloc_inst(), then copy both into the live f_hidg instance in
hidg_alloc().
• In hidg_bind(), set each endpoint’s bInterval based on whether the
user has written the attribute:
– If interval_user_set == false, use FS=10 / HS=4
– If interval_user_set == true, use the user’s value for both FS
& HS
Signed-off-by: Ben Hoff <hoff.benjamin.k@xxxxxxxxx>
---
Changes since v1:
- Added dedicated interval_show/store helpers
- Restored original default values (FS=10 ms, HS=4 µ-frame) for both
IN and OUT when unset.
Changes since v2:
- Corrected commit message
drivers/usb/gadget/function/f_hid.c | 119 ++++++++++++++++++++--------
drivers/usb/gadget/function/u_hid.h | 2 +
2 files changed, 90 insertions(+), 31 deletions(-)
diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index 740311c4fa24..3c4212929812 100644
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -62,6 +62,9 @@ struct f_hidg {
unsigned short report_desc_length;
char *report_desc;
unsigned short report_length;
+ unsigned char interval;
+ bool interval_user_set;
+
/*
* use_out_ep - if true, the OUT Endpoint (interrupt out method)
* will be used to receive reports from the host
@@ -156,10 +159,7 @@ static struct usb_endpoint_descriptor hidg_ss_in_ep_desc = {
.bEndpointAddress = USB_DIR_IN,
.bmAttributes = USB_ENDPOINT_XFER_INT,
/*.wMaxPacketSize = DYNAMIC */
- .bInterval = 4, /* FIXME: Add this field in the
- * HID gadget configuration?
- * (struct hidg_func_descriptor)
- */
+ /*.bInterval = DYNAMIC */
};
static struct usb_ss_ep_comp_descriptor hidg_ss_in_comp_desc = {
@@ -177,10 +177,7 @@ static struct usb_endpoint_descriptor hidg_ss_out_ep_desc = {
.bEndpointAddress = USB_DIR_OUT,
.bmAttributes = USB_ENDPOINT_XFER_INT,
/*.wMaxPacketSize = DYNAMIC */
- .bInterval = 4, /* FIXME: Add this field in the
- * HID gadget configuration?
- * (struct hidg_func_descriptor)
- */
+ /*.bInterval = DYNAMIC */
};
static struct usb_ss_ep_comp_descriptor hidg_ss_out_comp_desc = {
@@ -218,10 +215,7 @@ static struct usb_endpoint_descriptor hidg_hs_in_ep_desc = {
.bEndpointAddress = USB_DIR_IN,
.bmAttributes = USB_ENDPOINT_XFER_INT,
/*.wMaxPacketSize = DYNAMIC */
- .bInterval = 4, /* FIXME: Add this field in the
- * HID gadget configuration?
- * (struct hidg_func_descriptor)
- */
+ /* .bInterval = DYNAMIC */
};
static struct usb_endpoint_descriptor hidg_hs_out_ep_desc = {
@@ -230,10 +224,7 @@ static struct usb_endpoint_descriptor hidg_hs_out_ep_desc = {
.bEndpointAddress = USB_DIR_OUT,
.bmAttributes = USB_ENDPOINT_XFER_INT,
/*.wMaxPacketSize = DYNAMIC */
- .bInterval = 4, /* FIXME: Add this field in the
- * HID gadget configuration?
- * (struct hidg_func_descriptor)
- */
+ /*.bInterval = DYNAMIC */
};
static struct usb_descriptor_header *hidg_hs_descriptors_intout[] = {
@@ -259,10 +250,7 @@ static struct usb_endpoint_descriptor hidg_fs_in_ep_desc = {
.bEndpointAddress = USB_DIR_IN,
.bmAttributes = USB_ENDPOINT_XFER_INT,
/*.wMaxPacketSize = DYNAMIC */
- .bInterval = 10, /* FIXME: Add this field in the
- * HID gadget configuration?
- * (struct hidg_func_descriptor)
- */
+ /*.bInterval = DYNAMIC */
};
static struct usb_endpoint_descriptor hidg_fs_out_ep_desc = {
@@ -271,10 +259,7 @@ static struct usb_endpoint_descriptor hidg_fs_out_ep_desc = {
.bEndpointAddress = USB_DIR_OUT,
.bmAttributes = USB_ENDPOINT_XFER_INT,
/*.wMaxPacketSize = DYNAMIC */
- .bInterval = 10, /* FIXME: Add this field in the
- * HID gadget configuration?
- * (struct hidg_func_descriptor)
- */
+ /*.bInterval = DYNAMIC */
};
static struct usb_descriptor_header *hidg_fs_descriptors_intout[] = {
@@ -1202,6 +1187,16 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
hidg_hs_in_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length);
hidg_fs_in_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length);
hidg_ss_out_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length);
+
+ /* IN endpoints: FS default=10ms, HS default=4µ-frame; user override if set */
+ if (!hidg->interval_user_set) {
+ hidg_fs_in_ep_desc.bInterval = 10;
+ hidg_hs_in_ep_desc.bInterval = 4;
+ } else {
+ hidg_fs_in_ep_desc.bInterval = hidg->interval;
+ hidg_hs_in_ep_desc.bInterval = hidg->interval;
+ }
+
hidg_ss_out_comp_desc.wBytesPerInterval =
cpu_to_le16(hidg->report_length);
hidg_hs_out_ep_desc.wMaxPacketSize = cpu_to_le16(hidg->report_length);
@@ -1224,19 +1219,27 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
hidg_ss_out_ep_desc.bEndpointAddress =
hidg_fs_out_ep_desc.bEndpointAddress;
- if (hidg->use_out_ep)
+ if (hidg->use_out_ep) {
+ /* OUT endpoints: same defaults (FS=10, HS=4) unless user set */
+ if (!hidg->interval_user_set) {
+ hidg_fs_out_ep_desc.bInterval = 10;
+ hidg_hs_out_ep_desc.bInterval = 4;
+ } else {
+ hidg_fs_out_ep_desc.bInterval = hidg->interval;
+ hidg_hs_out_ep_desc.bInterval = hidg->interval;
+ }
status = usb_assign_descriptors(f,
- hidg_fs_descriptors_intout,
- hidg_hs_descriptors_intout,
- hidg_ss_descriptors_intout,
- hidg_ss_descriptors_intout);
- else
+ hidg_fs_descriptors_intout,
+ hidg_hs_descriptors_intout,
+ hidg_ss_descriptors_intout,
+ hidg_ss_descriptors_intout);
+ } else {
status = usb_assign_descriptors(f,
hidg_fs_descriptors_ssreport,
hidg_hs_descriptors_ssreport,
hidg_ss_descriptors_ssreport,
hidg_ss_descriptors_ssreport);
-
+ }
if (status)
goto fail;
@@ -1408,6 +1411,53 @@ static ssize_t f_hid_opts_report_desc_store(struct config_item *item,
CONFIGFS_ATTR(f_hid_opts_, report_desc);
+static ssize_t f_hid_opts_interval_show(struct config_item *item, char *page)
+{
+ struct f_hid_opts *opts = to_f_hid_opts(item);
+ int result;
+
+ mutex_lock(&opts->lock);
+ result = sprintf(page, "%d\n", opts->interval);
+ mutex_unlock(&opts->lock);
+
+ return result;
+}
+
+static ssize_t f_hid_opts_interval_store(struct config_item *item,
+ const char *page, size_t len)
+{
+ struct f_hid_opts *opts = to_f_hid_opts(item);
+ int ret;
+ unsigned int tmp;
+
+ mutex_lock(&opts->lock);
+ if (opts->refcnt) {
+ ret = -EBUSY;
+ goto end;
+ }
+
+ /* parse into a wider type first */
+ ret = kstrtouint(page, 0, &tmp);
+ if (ret)
+ goto end;
+
+ /* range-check against unsigned char max */
+ if (tmp > 255) {
+ ret = -EINVAL;
+ goto end;
+ }
+
+ opts->interval = (unsigned char)tmp;
+ opts->interval_user_set = true;
+ ret = len;
+
+end:
+ mutex_unlock(&opts->lock);
+ return ret;
+}
+
+CONFIGFS_ATTR(f_hid_opts_, interval);
+
static ssize_t f_hid_opts_dev_show(struct config_item *item, char *page)
{
struct f_hid_opts *opts = to_f_hid_opts(item);
@@ -1422,6 +1472,7 @@ static struct configfs_attribute *hid_attrs[] = {
&f_hid_opts_attr_protocol,
&f_hid_opts_attr_no_out_endpoint,
&f_hid_opts_attr_report_length,
+ &f_hid_opts_attr_interval,
&f_hid_opts_attr_report_desc,
&f_hid_opts_attr_dev,
NULL,
@@ -1468,6 +1519,10 @@ static struct usb_function_instance *hidg_alloc_inst(void)
if (!opts)
return ERR_PTR(-ENOMEM);
mutex_init(&opts->lock);
+
+ opts->interval = 4;
+ opts->interval_user_set = false;
+
opts->func_inst.free_func_inst = hidg_free_inst;
ret = &opts->func_inst;
@@ -1546,6 +1601,8 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi)
hidg->bInterfaceProtocol = opts->protocol;
hidg->report_length = opts->report_length;
hidg->report_desc_length = opts->report_desc_length;
+ hidg->interval = opts->interval;
+ hidg->interval_user_set = opts->interval_user_set;
if (opts->report_desc) {
hidg->report_desc = kmemdup(opts->report_desc,
opts->report_desc_length,
diff --git a/drivers/usb/gadget/function/u_hid.h b/drivers/usb/gadget/function/u_hid.h
index 84bb70292855..a9ed9720caee 100644
--- a/drivers/usb/gadget/function/u_hid.h
+++ b/drivers/usb/gadget/function/u_hid.h
@@ -25,6 +25,8 @@ struct f_hid_opts {
unsigned short report_desc_length;
unsigned char *report_desc;
bool report_desc_alloc;
+ unsigned char interval;
+ bool interval_user_set;
/*
* Protect the data form concurrent access by read/write
--
2.49.0
