[PATCH v2 3/3] Revert "usb: gadget: f_uac2/u_audio: add feedback endpoint support"

Ferry Toth
2021-08-26T19:15:21Z

This reverts commit 24f779dac8f3efb9629adc0e486914d93dc45517.

The commit is part of a series with commit
24f779dac8f3efb9629adc0e486914d93dc45517 causing a BUG on dwc3
hardware, at least on Intel Merrifield platform when configured
through configfs:
BUG: kernel NULL pointer dereference, address: 0000000000000008
...
RIP: 0010:dwc3_gadget_del_and_unmap_request+0x19/0xe0
...
Call Trace:
dwc3_remove_requests.constprop.0+0x12f/0x170
__dwc3_gadget_ep_disable+0x7a/0x160
dwc3_gadget_ep_disable+0x3d/0xd0
usb_ep_disable+0x1c/0x70
u_audio_stop_capture+0x79/0x120 [u_audio]
afunc_set_alt+0x73/0x80 [usb_f_uac2]
composite_setup+0x224/0x1b90 [libcomposite]

Pavel's suggestion to add
`echo "adaptive" > functions/uac2.usb0/c_sync` to the configfs script
resolves the issue.
Thinh suggests "the crash is probably because of f_uac2 prematurely
freeing feedback request before its completion. usb_ep_dequeue() is
asynchronous. dwc2() may treat it as a synchronous call so you didn't
get a crash."

Revert as this is a regression and the kernel shouldn't crash depending
on configuration parameters.

Signed-off-by: Ferry Toth <ftoth@exalondelft.nl>
---
drivers/usb/gadget/function/f_uac2.c | 49 +----------
drivers/usb/gadget/function/u_audio.c | 119 +-------------------------
drivers/usb/gadget/function/u_audio.h | 3 -
3 files changed, 3 insertions(+), 168 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 5d63244ba319..7aa4c8bc5a1a 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -240,7 +240,7 @@ static struct usb_interface_descriptor std_as_out_if1_desc = {
.bDescriptorType = USB_DT_INTERFACE,

.bAlternateSetting = 1,
- .bNumEndpoints = 2,
+ .bNumEndpoints = 1,
.bInterfaceClass = USB_CLASS_AUDIO,
.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
.bInterfaceProtocol = UAC_VERSION_2,
@@ -317,37 +317,6 @@ static struct uac2_iso_endpoint_descriptor as_iso_out_desc = {
.wLockDelay = 0,
};

-/* STD AS ISO IN Feedback Endpoint */
-static struct usb_endpoint_descriptor fs_epin_fback_desc = {
- .bLength = USB_DT_ENDPOINT_SIZE,
- .bDescriptorType = USB_DT_ENDPOINT,
-
- .bEndpointAddress = USB_DIR_IN,
- .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_USAGE_FEEDBACK,
- .wMaxPacketSize = cpu_to_le16(3),
- .bInterval = 1,
-};
-
-static struct usb_endpoint_descriptor hs_epin_fback_desc = {
- .bLength = USB_DT_ENDPOINT_SIZE,
- .bDescriptorType = USB_DT_ENDPOINT,
-
- .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_USAGE_FEEDBACK,
- .wMaxPacketSize = cpu_to_le16(4),
- .bInterval = 4,
-};
-
-static struct usb_endpoint_descriptor ss_epin_fback_desc = {
- .bLength = USB_DT_ENDPOINT_SIZE,
- .bDescriptorType = USB_DT_ENDPOINT,
-
- .bEndpointAddress = USB_DIR_IN,
- .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_USAGE_FEEDBACK,
- .wMaxPacketSize = cpu_to_le16(4),
- .bInterval = 4,
-};
-
-
/* Audio Streaming IN Interface - Alt0 */
static struct usb_interface_descriptor std_as_in_if0_desc = {
.bLength = sizeof std_as_in_if0_desc,
@@ -462,7 +431,6 @@ static struct usb_descriptor_header *fs_audio_desc[] = {
(struct usb_descriptor_header *)&as_out_fmt1_desc,
(struct usb_descriptor_header *)&fs_epout_desc,
(struct usb_descriptor_header *)&as_iso_out_desc,
- (struct usb_descriptor_header *)&fs_epin_fback_desc,

(struct usb_descriptor_header *)&std_as_in_if0_desc,
(struct usb_descriptor_header *)&std_as_in_if1_desc,
@@ -493,7 +461,6 @@ static struct usb_descriptor_header *hs_audio_desc[] = {
(struct usb_descriptor_header *)&as_out_fmt1_desc,
(struct usb_descriptor_header *)&hs_epout_desc,
(struct usb_descriptor_header *)&as_iso_out_desc,
- (struct usb_descriptor_header *)&hs_epin_fback_desc,

(struct usb_descriptor_header *)&std_as_in_if0_desc,
(struct usb_descriptor_header *)&std_as_in_if1_desc,
@@ -525,7 +492,6 @@ static struct usb_descriptor_header *ss_audio_desc[] = {
(struct usb_descriptor_header *)&ss_epout_desc,
(struct usb_descriptor_header *)&ss_epout_desc_comp,
(struct usb_descriptor_header *)&as_iso_out_desc,
- (struct usb_descriptor_header *)&ss_epin_fback_desc,

(struct usb_descriptor_header *)&std_as_in_if0_desc,
(struct usb_descriptor_header *)&std_as_in_if1_desc,
@@ -602,26 +568,22 @@ static void setup_headers(struct f_uac2_opts *opts,
struct usb_ss_ep_comp_descriptor *epin_desc_comp = NULL;
struct usb_endpoint_descriptor *epout_desc;
struct usb_endpoint_descriptor *epin_desc;
- struct usb_endpoint_descriptor *epin_fback_desc;
int i;

switch (speed) {
case USB_SPEED_FULL:
epout_desc = &fs_epout_desc;
epin_desc = &fs_epin_desc;
- epin_fback_desc = &fs_epin_fback_desc;
break;
case USB_SPEED_HIGH:
epout_desc = &hs_epout_desc;
epin_desc = &hs_epin_desc;
- epin_fback_desc = &hs_epin_fback_desc;
break;
default:
epout_desc = &ss_epout_desc;
epin_desc = &ss_epin_desc;
epout_desc_comp = &ss_epout_desc_comp;
epin_desc_comp = &ss_epin_desc_comp;
- epin_fback_desc = &ss_epin_fback_desc;
}

i = 0;
@@ -649,7 +611,6 @@ static void setup_headers(struct f_uac2_opts *opts,
headers[i++] = USBDHDR(epout_desc_comp);

headers[i++] = USBDHDR(&as_iso_out_desc);
- headers[i++] = USBDHDR(epin_fback_desc);
}
if (EPIN_EN(opts)) {
headers[i++] = USBDHDR(&std_as_in_if0_desc);
@@ -883,12 +844,6 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
return -ENODEV;
}
- agdev->in_ep_fback = usb_ep_autoconfig(gadget,
- &fs_epin_fback_desc);
- if (!agdev->in_ep_fback) {
- dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
- return -ENODEV;
- }
}

if (EPIN_EN(uac2_opts)) {
@@ -912,10 +867,8 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
le16_to_cpu(ss_epout_desc.wMaxPacketSize));

hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
- hs_epin_fback_desc.bEndpointAddress = fs_epin_fback_desc.bEndpointAddress;
hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
ss_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
- ss_epin_fback_desc.bEndpointAddress = fs_epin_fback_desc.bEndpointAddress;
ss_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;

setup_descriptor(uac2_opts);
diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index f637ebec80b0..5fbceee897a3 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -38,10 +38,6 @@ struct uac_rtd_params {
unsigned int max_psize; /* MaxPacketSize of endpoint */

struct usb_request **reqs;
-
- struct usb_request *req_fback; /* Feedback endpoint request */
- unsigned int ffback; /* Real frequency reported by feedback endpoint */
- bool fb_ep_enabled; /* if the ep is enabled */
};

struct snd_uac_chip {
@@ -74,32 +70,6 @@ static const struct snd_pcm_hardware uac_pcm_hardware = {
.periods_min = MIN_PERIODS,
};

-static void u_audio_set_fback_frequency(enum usb_device_speed speed,
- unsigned int freq, void *buf)
-{
- u32 ff = 0;
-
- if (speed == USB_SPEED_FULL) {
- /*
- * Full-speed feedback endpoints report frequency
- * in samples/microframe
- * Format is encoded in Q10.10 left-justified in the 24 bits,
- * so that it has a Q10.14 format.
- */
- ff = DIV_ROUND_UP((freq << 14), 1000);
- } else {
- /*
- * High-speed feedback endpoints report frequency
- * in samples/microframe.
- * Format is encoded in Q12.13 fitted into four bytes so that
- * the binary point is located between the second and the third
- * byte fromat (that is Q16.16)
- */
- ff = DIV_ROUND_UP((freq << 13), 1000);
- }
- *(__le32 *)buf = cpu_to_le32(ff);
-}
-
static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
{
unsigned int pending;
@@ -203,34 +173,6 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
dev_err(uac->card->dev, "%d Error!\n", __LINE__);
}

-static void u_audio_iso_fback_complete(struct usb_ep *ep,
- struct usb_request *req)
-{
- struct uac_rtd_params *prm = req->context;
- struct snd_uac_chip *uac = prm->uac;
- struct g_audio *audio_dev = uac->audio_dev;
- int status = req->status;
- unsigned long flags;
-
- /* i/f shutting down */
- if (!prm->fb_ep_enabled || req->status == -ESHUTDOWN)
- return;
-
- /*
- * We can't really do much about bad xfers.
- * Afterall, the ISOCH xfers could fail legitimately.
- */
- if (status)
- pr_debug("%s: iso_complete status(%d) %d/%d\n",
- __func__, status, req->actual, req->length);
-
- u_audio_set_fback_frequency(audio_dev->gadget->speed,
- prm->ffback, req->buf);
-
- if (usb_ep_queue(ep, req, GFP_ATOMIC))
- dev_err(uac->card->dev, "%d Error!\n", __LINE__);
-}
-
static int uac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
@@ -393,33 +335,14 @@ static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
dev_err(uac->card->dev, "%s:%d Error!\n", __func__, __LINE__);
}

-static inline void free_ep_fback(struct uac_rtd_params *prm, struct usb_ep *ep)
-{
- struct snd_uac_chip *uac = prm->uac;
-
- if (!prm->fb_ep_enabled)
- return;
-
- prm->fb_ep_enabled = false;
-
- if (prm->req_fback) {
- usb_ep_dequeue(ep, prm->req_fback);
- kfree(prm->req_fback->buf);
- usb_ep_free_request(ep, prm->req_fback);
- prm->req_fback = NULL;
- }
-
- if (usb_ep_disable(ep))
- dev_err(uac->card->dev, "%s:%d Error!\n", __func__, __LINE__);
-}

int u_audio_start_capture(struct g_audio *audio_dev)
{
struct snd_uac_chip *uac = audio_dev->uac;
struct usb_gadget *gadget = audio_dev->gadget;
struct device *dev = &gadget->dev;
- struct usb_request *req, *req_fback;
- struct usb_ep *ep, *ep_fback;
+ struct usb_request *req;
+ struct usb_ep *ep;
struct uac_rtd_params *prm;
struct uac_params *params = &audio_dev->params;
int req_len, i;
@@ -451,42 +374,6 @@ int u_audio_start_capture(struct g_audio *audio_dev)
dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
}

- ep_fback = audio_dev->in_ep_fback;
- if (!ep_fback)
- return 0;
-
- /* Setup feedback endpoint */
- config_ep_by_speed(gadget, &audio_dev->func, ep_fback);
- prm->fb_ep_enabled = true;
- usb_ep_enable(ep_fback);
- req_len = ep_fback->maxpacket;
-
- req_fback = usb_ep_alloc_request(ep_fback, GFP_ATOMIC);
- if (req_fback == NULL)
- return -ENOMEM;
-
- prm->req_fback = req_fback;
- req_fback->zero = 0;
- req_fback->context = prm;
- req_fback->length = req_len;
- req_fback->complete = u_audio_iso_fback_complete;
-
- req_fback->buf = kzalloc(req_len, GFP_ATOMIC);
- if (!req_fback->buf)
- return -ENOMEM;
-
- /*
- * Configure the feedback endpoint's reported frequency.
- * Always start with original frequency since its deviation can't
- * be meauserd at start of playback
- */
- prm->ffback = params->c_srate;
- u_audio_set_fback_frequency(audio_dev->gadget->speed,
- prm->ffback, req_fback->buf);
-
- if (usb_ep_queue(ep_fback, req_fback, GFP_ATOMIC))
- dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
-
return 0;
}
EXPORT_SYMBOL_GPL(u_audio_start_capture);
@@ -495,8 +382,6 @@ void u_audio_stop_capture(struct g_audio *audio_dev)
{
struct snd_uac_chip *uac = audio_dev->uac;

- if (audio_dev->in_ep_fback)
- free_ep_fback(&uac->c_prm, audio_dev->in_ep_fback);
free_ep(&uac->c_prm, audio_dev->out_ep);
}
EXPORT_SYMBOL_GPL(u_audio_stop_capture);
diff --git a/drivers/usb/gadget/function/u_audio.h b/drivers/usb/gadget/function/u_audio.h
index 53e6baf55cbf..5ea6b86f1fda 100644
--- a/drivers/usb/gadget/function/u_audio.h
+++ b/drivers/usb/gadget/function/u_audio.h
@@ -30,10 +30,7 @@ struct g_audio {
struct usb_gadget *gadget;

struct usb_ep *in_ep;
-
struct usb_ep *out_ep;
- /* feedback IN endpoint corresponding to out_ep */
- struct usb_ep *in_ep_fback;

/* Max packet size for all in_ep possible speeds */
unsigned int in_ep_maxpsize;
--
2.30.2