diff mbox series

[v2] bluetooth: add quirk using packet size 60

Message ID 20241118085757.3678244-1-hildawu@realtek.com (mailing list archive)
State New
Headers show
Series [v2] bluetooth: add quirk using packet size 60 | expand

Checks

Context Check Description
tedd_an/pre-ci_am success Success
tedd_an/SubjectPrefix fail "Bluetooth: " prefix is not specified in the subject
tedd_an/BuildKernel success BuildKernel PASS
tedd_an/CheckAllWarning success CheckAllWarning PASS
tedd_an/CheckSparse success CheckSparse PASS
tedd_an/BuildKernel32 success BuildKernel32 PASS
tedd_an/TestRunnerSetup success TestRunnerSetup PASS
tedd_an/TestRunner_l2cap-tester success TestRunner PASS
tedd_an/TestRunner_iso-tester fail TestRunner_iso-tester: WARNING: possible circular locking dependency detected
tedd_an/TestRunner_bnep-tester success TestRunner PASS
tedd_an/TestRunner_mgmt-tester fail TestRunner_mgmt-tester: Total: 492, Passed: 487 (99.0%), Failed: 1, Not Run: 4
tedd_an/TestRunner_rfcomm-tester success TestRunner PASS
tedd_an/TestRunner_sco-tester success TestRunner PASS
tedd_an/TestRunner_ioctl-tester success TestRunner PASS
tedd_an/TestRunner_mesh-tester success TestRunner PASS
tedd_an/TestRunner_smp-tester success TestRunner PASS
tedd_an/TestRunner_userchan-tester success TestRunner PASS

Commit Message

Hilda Wu Nov. 18, 2024, 8:57 a.m. UTC
The RTL8852BE-VT supports USB alternate setting 6.
However, its descriptor does not report this capability to the host.
Therefore, a quirk is needed to bypass the RTL8852BE-VT's descriptor
and allow it to use USB ALT 6 directly.

The btmon log below shows the case that WBS with the USB alternate
setting 6.

> ACL Data RX: Handle 2 flags 0x02 dlen 18       #5338 [hci0] 91.977373
      Channel: 70 len 14 [PSM 3 mode Basic (0x00)] {chan 3}
      RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
         Address: 0x09 cr 0 dlci 0x02
         Control: 0xff poll/final 1
         Length: 9
         FCS: 0x5c
         Credits: 4
        41 54 2b 42 43 53 3d 32 0d 5c                    AT+BCS=2.\    >
< ACL Data TX: Handle 2 flags 0x00 dlen 15       #5339 [hci0] 91.978294
      Channel: 64 len 11 [PSM 3 mode Basic (0x00)] {chan 3}
      RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
         Address: 0x0b cr 1 dlci 0x02
         Control: 0xff poll/final 1
         Length: 6
         FCS: 0x86
         Credits: 1
        0d 0a 4f 4b 0d 0a 86                             ..OK...       >
< HCI Command: Enhanced.. (0x01|0x003d) plen 59  #5340 [hci0] 91.978326
        Handle: 2
        Transmit bandwidth: 8000
        Receive bandwidth: 8000
        Max latency: 13
        Packet type: 0x0380
          3-EV3 may not be used
          2-EV5 may not be used
          3-EV5 may not be used
        Retransmission effort: Optimize for link quality (0x02)
> HCI Event: Command Status (0x0f) plen 4        #5341 [hci0] 91.981723
      Enhanced Setup Synchronous Connection (0x01|0x003d) ncmd 2
        Status: Success (0x00)
> HCI Event: Number of Complete.. (0x13) plen 5  #5342 [hci0] 91.982705
        Num handles: 1
        Handle: 2
        Count: 1
> HCI Event: Synchronous Conne.. (0x2c) plen 17  #5343 [hci0] 92.015758
        Status: Success (0x00)
        Handle: 3
        Address: 78:A7:EB:4C:53:4D (OUI 78-A7-EB)
        Link type: eSCO (0x02)
        Transmission interval: 0x0c
        Retransmission window: 0x04
        RX packet length: 60
        TX packet length: 60
        Air mode: Transparent (0x03)
@ MGMT Open: bt_main_th.. (privileged) version 1.22  {0x0003} 92.016366
@ MGMT Command: Unknown (0x0101) plen 11             {0x0003} 92.016374
        00 00 78 a7 eb 4c 53 4d 00 01 02                 ..x..LSM...   >
@ MGMT Close: bt_main_thread                         {0x0003} 92.016409
< ACL Data TX: Handle 2 flags 0x00 dlen 22       #5344 [hci0] 92.017651
      Channel: 64 len 18 [PSM 3 mode Basic (0x00)] {chan 3}
      RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
         Address: 0x0b cr 1 dlci 0x02
         Control: 0xef poll/final 0
         Length: 14
         FCS: 0x9a
        0d 0a 2b 43 49 45 56 3a 20 32 2c 32 0d 0a 9a     ..+CIEV: 2,2..>
...
> SCO Data RX: Handle 3 flags 0x00 dlen 60       #5349 [hci0] 92.037778
< SCO Data TX: Handle 3 flags 0x00 dlen 60       #5350 [hci0] 92.038218
> HCI Event: Max Slots Change (0x1b) plen 3      #5351 [hci0] 92.040758
        Handle: 2
        Max slots: 1
> HCI Event: Number of Complete.. (0x13) plen 5  #5352 [hci0] 92.041760
        Num handles: 1
        Handle: 2
        Count: 1
> HCI Event: Number of Complete.. (0x13) plen 5  #5353 [hci0] 92.044784
        Num handles: 1
        Handle: 2
        Count: 1
> SCO Data RX: Handle 3 flags 0x00 dlen 60       #5354 [hci0] 92.047706
< SCO Data TX: Handle 3 flags 0x00 dlen 60       #5355 [hci0] 92.048226
> SCO Data RX: Handle 3 flags 0x00 dlen 60       #5356 [hci0] 92.057706
< SCO Data TX: Handle 3 flags 0x00 dlen 60       #5357 [hci0] 92.058179
...
> SCO Data RX: Handle 3 flags 0x00 dlen 60       #5362 [hci0] 92.067775
> SCO Data RX: Handle 3 flags 0x00 dlen 60       #5363 [hci0] 92.067780
< SCO Data TX: Handle 3 flags 0x00 dlen 60       #5364 [hci0] 92.068288
< SCO Data TX: Handle 3 flags 0x00 dlen 60       #5365 [hci0] 92.068322
> SCO Data RX: Handle 3 flags 0x00 dlen 60       #5366 [hci0] 92.077733
< SCO Data TX: Handle 3 flags 0x00 dlen 60       #5367 [hci0] 92.078263

Signed-off-by: Alex Lu <alex_lu@realsil.com.cn>
Signed-off-by: Hilda Wu <hildawu@realtek.com>

---
Change:
v2: Use btusb_find_altsetting replace duplicating logic, add tested log.
---
---
 drivers/bluetooth/btrtl.c |  3 ++
 drivers/bluetooth/btrtl.h |  1 +
 drivers/bluetooth/btusb.c | 82 +++++++++++++++++++++++++++++----------
 3 files changed, 66 insertions(+), 20 deletions(-)

Comments

bluez.test.bot@gmail.com Nov. 18, 2024, 9:34 a.m. UTC | #1
This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=910549

---Test result---

Test Summary:
CheckPatch                    PENDING   0.37 seconds
GitLint                       PENDING   0.30 seconds
SubjectPrefix                 FAIL      0.41 seconds
BuildKernel                   PASS      25.02 seconds
CheckAllWarning               PASS      27.21 seconds
CheckSparse                   PASS      30.28 seconds
BuildKernel32                 PASS      24.40 seconds
TestRunnerSetup               PASS      433.30 seconds
TestRunner_l2cap-tester       PASS      20.02 seconds
TestRunner_iso-tester         FAIL      31.38 seconds
TestRunner_bnep-tester        PASS      5.53 seconds
TestRunner_mgmt-tester        FAIL      121.15 seconds
TestRunner_rfcomm-tester      PASS      7.71 seconds
TestRunner_sco-tester         PASS      11.32 seconds
TestRunner_ioctl-tester       PASS      8.00 seconds
TestRunner_mesh-tester        PASS      5.91 seconds
TestRunner_smp-tester         PASS      6.97 seconds
TestRunner_userchan-tester    PASS      4.92 seconds
IncrementalBuild              PENDING   0.90 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: SubjectPrefix - FAIL
Desc: Check subject contains "Bluetooth" prefix
Output:
"Bluetooth: " prefix is not specified in the subject
##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
Total: 124, Passed: 120 (96.8%), Failed: 0, Not Run: 4
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 492, Passed: 487 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
LL Privacy - Start Discovery 2 (Disable RL)          Failed       0.191 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth
Pauli Virtanen Nov. 18, 2024, 5:01 p.m. UTC | #2
Hi,

ma, 2024-11-18 kello 16:57 +0800, Hilda Wu kirjoitti:
> The RTL8852BE-VT supports USB alternate setting 6.
> However, its descriptor does not report this capability to the host.
> Therefore, a quirk is needed to bypass the RTL8852BE-VT's descriptor
> and allow it to use USB ALT 6 directly.
> 
> The btmon log below shows the case that WBS with the USB alternate
> setting 6.
> 
> > ACL Data RX: Handle 2 flags 0x02 dlen 18       #5338 [hci0] 91.977373
>       Channel: 70 len 14 [PSM 3 mode Basic (0x00)] {chan 3}
>       RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
>          Address: 0x09 cr 0 dlci 0x02
>          Control: 0xff poll/final 1
>          Length: 9
>          FCS: 0x5c
>          Credits: 4
>         41 54 2b 42 43 53 3d 32 0d 5c                    AT+BCS=2.\    >
> < ACL Data TX: Handle 2 flags 0x00 dlen 15       #5339 [hci0] 91.978294
>       Channel: 64 len 11 [PSM 3 mode Basic (0x00)] {chan 3}
>       RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
>          Address: 0x0b cr 1 dlci 0x02
>          Control: 0xff poll/final 1
>          Length: 6
>          FCS: 0x86
>          Credits: 1
>         0d 0a 4f 4b 0d 0a 86                             ..OK...       >
> < HCI Command: Enhanced.. (0x01|0x003d) plen 59  #5340 [hci0] 91.978326
>         Handle: 2
>         Transmit bandwidth: 8000
>         Receive bandwidth: 8000
>         Max latency: 13
>         Packet type: 0x0380
>           3-EV3 may not be used
>           2-EV5 may not be used
>           3-EV5 may not be used
>         Retransmission effort: Optimize for link quality (0x02)
> > HCI Event: Command Status (0x0f) plen 4        #5341 [hci0] 91.981723
>       Enhanced Setup Synchronous Connection (0x01|0x003d) ncmd 2
>         Status: Success (0x00)
> > HCI Event: Number of Complete.. (0x13) plen 5  #5342 [hci0] 91.982705
>         Num handles: 1
>         Handle: 2
>         Count: 1
> > HCI Event: Synchronous Conne.. (0x2c) plen 17  #5343 [hci0] 92.015758
>         Status: Success (0x00)
>         Handle: 3
>         Address: 78:A7:EB:4C:53:4D (OUI 78-A7-EB)
>         Link type: eSCO (0x02)
>         Transmission interval: 0x0c
>         Retransmission window: 0x04
>         RX packet length: 60
>         TX packet length: 60
>         Air mode: Transparent (0x03)
> @ MGMT Open: bt_main_th.. (privileged) version 1.22  {0x0003} 92.016366
> @ MGMT Command: Unknown (0x0101) plen 11             {0x0003} 92.016374
>         00 00 78 a7 eb 4c 53 4d 00 01 02                 ..x..LSM...   >
> @ MGMT Close: bt_main_thread                         {0x0003} 92.016409
> < ACL Data TX: Handle 2 flags 0x00 dlen 22       #5344 [hci0] 92.017651
>       Channel: 64 len 18 [PSM 3 mode Basic (0x00)] {chan 3}
>       RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
>          Address: 0x0b cr 1 dlci 0x02
>          Control: 0xef poll/final 0
>          Length: 14
>          FCS: 0x9a
>         0d 0a 2b 43 49 45 56 3a 20 32 2c 32 0d 0a 9a     ..+CIEV: 2,2..>
> ...
> > SCO Data RX: Handle 3 flags 0x00 dlen 60       #5349 [hci0] 92.037778
> < SCO Data TX: Handle 3 flags 0x00 dlen 60       #5350 [hci0] 92.038218
> > HCI Event: Max Slots Change (0x1b) plen 3      #5351 [hci0] 92.040758
>         Handle: 2
>         Max slots: 1
> > HCI Event: Number of Complete.. (0x13) plen 5  #5352 [hci0] 92.041760
>         Num handles: 1
>         Handle: 2
>         Count: 1
> > HCI Event: Number of Complete.. (0x13) plen 5  #5353 [hci0] 92.044784
>         Num handles: 1
>         Handle: 2
>         Count: 1
> > SCO Data RX: Handle 3 flags 0x00 dlen 60       #5354 [hci0] 92.047706
> < SCO Data TX: Handle 3 flags 0x00 dlen 60       #5355 [hci0] 92.048226
> > SCO Data RX: Handle 3 flags 0x00 dlen 60       #5356 [hci0] 92.057706
> < SCO Data TX: Handle 3 flags 0x00 dlen 60       #5357 [hci0] 92.058179
> ...
> > SCO Data RX: Handle 3 flags 0x00 dlen 60       #5362 [hci0] 92.067775
> > SCO Data RX: Handle 3 flags 0x00 dlen 60       #5363 [hci0] 92.067780
> < SCO Data TX: Handle 3 flags 0x00 dlen 60       #5364 [hci0] 92.068288
> < SCO Data TX: Handle 3 flags 0x00 dlen 60       #5365 [hci0] 92.068322
> > SCO Data RX: Handle 3 flags 0x00 dlen 60       #5366 [hci0] 92.077733
> < SCO Data TX: Handle 3 flags 0x00 dlen 60       #5367 [hci0] 92.078263
> 
> Signed-off-by: Alex Lu <alex_lu@realsil.com.cn>
> Signed-off-by: Hilda Wu <hildawu@realtek.com>
> 
> ---
> Change:
> v2: Use btusb_find_altsetting replace duplicating logic, add tested log.
> ---
> ---
>  drivers/bluetooth/btrtl.c |  3 ++
>  drivers/bluetooth/btrtl.h |  1 +
>  drivers/bluetooth/btusb.c | 82 +++++++++++++++++++++++++++++----------
>  3 files changed, 66 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/bluetooth/btrtl.c b/drivers/bluetooth/btrtl.c
> index 83025f457ca0..7efd733f9e84 100644
> --- a/drivers/bluetooth/btrtl.c
> +++ b/drivers/bluetooth/btrtl.c
> @@ -1312,6 +1312,9 @@ void btrtl_set_quirks(struct hci_dev *hdev, struct btrtl_device_info *btrtl_dev)
>  		    btrtl_dev->project_id == CHIP_ID_8852C)
>  			set_bit(HCI_QUIRK_USE_MSFT_EXT_ADDRESS_FILTER, &hdev->quirks);
>  
> +		if (btrtl_dev->project_id == CHIP_ID_8852BT)
> +			btrealtek_set_flag(hdev, REALTEK_ALT6_FORCE);
> +
>  		hci_set_aosp_capable(hdev);
>  		break;
>  	default:
> diff --git a/drivers/bluetooth/btrtl.h b/drivers/bluetooth/btrtl.h
> index a2d9d34f9fb0..ffec2fca88ec 100644
> --- a/drivers/bluetooth/btrtl.h
> +++ b/drivers/bluetooth/btrtl.h
> @@ -105,6 +105,7 @@ struct rtl_vendor_cmd {
>  
>  enum {
>  	REALTEK_ALT6_CONTINUOUS_TX_CHIP,
> +	REALTEK_ALT6_FORCE,
>  
>  	__REALTEK_NUM_FLAGS,
>  };
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 279fe6c115fa..0a2107baf18a 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -814,6 +814,7 @@ struct qca_dump_info {
>  #define BTUSB_USE_ALT3_FOR_WBS	15
>  #define BTUSB_ALT6_CONTINUOUS_TX	16
>  #define BTUSB_HW_SSR_ACTIVE	17
> +#define BTUSB_ISOC_ALT_CHANGED	18
>  
>  struct btusb_data {
>  	struct hci_dev       *hdev;
> @@ -866,6 +867,7 @@ struct btusb_data {
>  	unsigned int air_mode;
>  	bool usb_alt6_packet_flow;
>  	int isoc_altsetting;
> +	u16 isoc_mps;
>  	int suspend_count;
>  
>  	int (*recv_event)(struct hci_dev *hdev, struct sk_buff *skb);
> @@ -2140,16 +2142,58 @@ static void btusb_notify(struct hci_dev *hdev, unsigned int evt)
>  	}
>  }
>  
> +static struct usb_host_interface *btusb_find_altsetting(struct btusb_data *data,
> +							int alt)
> +{
> +	struct usb_interface *intf = data->isoc;
> +	int i;
> +
> +	BT_DBG("Looking for Alt no :%d", alt);
> +
> +	if (!intf)
> +		return NULL;
> +
> +	for (i = 0; i < intf->num_altsetting; i++) {
> +		if (intf->altsetting[i].desc.bAlternateSetting == alt)
> +			return &intf->altsetting[i];
> +	}
> +
> +	return NULL;
> +}
> +
>  static inline int __set_isoc_interface(struct hci_dev *hdev, int altsetting)
>  {
>  	struct btusb_data *data = hci_get_drvdata(hdev);
>  	struct usb_interface *intf = data->isoc;
>  	struct usb_endpoint_descriptor *ep_desc;
> +	struct usb_host_interface *alt;
>  	int i, err;
>  
>  	if (!data->isoc)
>  		return -ENODEV;
>  
> +	/* For some Realtek chips, they actually have the altsetting 6, but its
> +	 * altsetting descriptor is not exposed. We can activate altsetting 6 by
> +	 * replacing the altsetting 5.
> +	 */
> +	if (altsetting == 6 && !btusb_find_altsetting(data, 6) &&
> +	    btrealtek_test_flag(hdev, REALTEK_ALT6_FORCE)) {

The btrealtek_*_flag() access priv data without checking that the
driver is RTL, probably return garbage/crash for other drivers.

AFAIK they can be used only when it is guaranteed the driver is RTL,
which is not the case here.

> +		alt = btusb_find_altsetting(data, 5);
> +		if (alt) {
> +			data->isoc_mps = 49;
> +			for (i = 0; i < alt->desc.bNumEndpoints; i++) {
> +				ep_desc = &alt->endpoint[i].desc;
> +				if (!usb_endpoint_xfer_isoc(ep_desc))
> +					continue;
> +				data->isoc_mps =
> +					le16_to_cpu(ep_desc->wMaxPacketSize);
> +				ep_desc->wMaxPacketSize = cpu_to_le16(63);
> +			}
> +			alt->desc.bAlternateSetting = 6;
> +			set_bit(BTUSB_ISOC_ALT_CHANGED, &data->flags);
> +		}
> +	}
> +
>  	err = usb_set_interface(data->udev, data->isoc_ifnum, altsetting);
>  	if (err < 0) {
>  		bt_dev_err(hdev, "setting interface failed (%d)", -err);
> @@ -2161,6 +2205,22 @@ static inline int __set_isoc_interface(struct hci_dev *hdev, int altsetting)
>  	data->isoc_tx_ep = NULL;
>  	data->isoc_rx_ep = NULL;
>  
> +	/* Recover alt 5 desc if alt 0 is set. */
> +	if (!altsetting && test_bit(BTUSB_ISOC_ALT_CHANGED, &data->flags)) {
> +		alt = btusb_find_altsetting(data, 6);
> +		if (alt) {
> +			for (i = 0; i < alt->desc.bNumEndpoints; i++) {
> +				ep_desc = &alt->endpoint[i].desc;
> +				if (!usb_endpoint_xfer_isoc(ep_desc))
> +					continue;
> +				ep_desc->wMaxPacketSize =
> +					cpu_to_le16(data->isoc_mps);
> +			}
> +			alt->desc.bAlternateSetting = 5;
> +			clear_bit(BTUSB_ISOC_ALT_CHANGED, &data->flags);
> +		}
> +	}
> +
>  	for (i = 0; i < intf->cur_altsetting->desc.bNumEndpoints; i++) {
>  		ep_desc = &intf->cur_altsetting->endpoint[i].desc;
>  
> @@ -2223,25 +2283,6 @@ static int btusb_switch_alt_setting(struct hci_dev *hdev, int new_alts)
>  	return 0;
>  }
>  
> -static struct usb_host_interface *btusb_find_altsetting(struct btusb_data *data,
> -							int alt)
> -{
> -	struct usb_interface *intf = data->isoc;
> -	int i;
> -
> -	BT_DBG("Looking for Alt no :%d", alt);
> -
> -	if (!intf)
> -		return NULL;
> -
> -	for (i = 0; i < intf->num_altsetting; i++) {
> -		if (intf->altsetting[i].desc.bAlternateSetting == alt)
> -			return &intf->altsetting[i];
> -	}
> -
> -	return NULL;
> -}
> -
>  static void btusb_work(struct work_struct *work)
>  {
>  	struct btusb_data *data = container_of(work, struct btusb_data, work);
> @@ -2279,7 +2320,8 @@ static void btusb_work(struct work_struct *work)
>  			 * MTU >= 3 (packets) * 25 (size) - 3 (headers) = 72
>  			 * see also Core spec 5, vol 4, B 2.1.1 & Table 2.1.
>  			 */
> -			if (btusb_find_altsetting(data, 6))
> +			if (btusb_find_altsetting(data, 6) ||
> +			    btrealtek_test_flag(hdev, REALTEK_ALT6_FORCE))

Same issue here.

>  				new_alts = 6;
>  			else if (btusb_find_altsetting(data, 3) &&
>  				 hdev->sco_mtu >= 72 &&
diff mbox series

Patch

diff --git a/drivers/bluetooth/btrtl.c b/drivers/bluetooth/btrtl.c
index 83025f457ca0..7efd733f9e84 100644
--- a/drivers/bluetooth/btrtl.c
+++ b/drivers/bluetooth/btrtl.c
@@ -1312,6 +1312,9 @@  void btrtl_set_quirks(struct hci_dev *hdev, struct btrtl_device_info *btrtl_dev)
 		    btrtl_dev->project_id == CHIP_ID_8852C)
 			set_bit(HCI_QUIRK_USE_MSFT_EXT_ADDRESS_FILTER, &hdev->quirks);
 
+		if (btrtl_dev->project_id == CHIP_ID_8852BT)
+			btrealtek_set_flag(hdev, REALTEK_ALT6_FORCE);
+
 		hci_set_aosp_capable(hdev);
 		break;
 	default:
diff --git a/drivers/bluetooth/btrtl.h b/drivers/bluetooth/btrtl.h
index a2d9d34f9fb0..ffec2fca88ec 100644
--- a/drivers/bluetooth/btrtl.h
+++ b/drivers/bluetooth/btrtl.h
@@ -105,6 +105,7 @@  struct rtl_vendor_cmd {
 
 enum {
 	REALTEK_ALT6_CONTINUOUS_TX_CHIP,
+	REALTEK_ALT6_FORCE,
 
 	__REALTEK_NUM_FLAGS,
 };
diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 279fe6c115fa..0a2107baf18a 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -814,6 +814,7 @@  struct qca_dump_info {
 #define BTUSB_USE_ALT3_FOR_WBS	15
 #define BTUSB_ALT6_CONTINUOUS_TX	16
 #define BTUSB_HW_SSR_ACTIVE	17
+#define BTUSB_ISOC_ALT_CHANGED	18
 
 struct btusb_data {
 	struct hci_dev       *hdev;
@@ -866,6 +867,7 @@  struct btusb_data {
 	unsigned int air_mode;
 	bool usb_alt6_packet_flow;
 	int isoc_altsetting;
+	u16 isoc_mps;
 	int suspend_count;
 
 	int (*recv_event)(struct hci_dev *hdev, struct sk_buff *skb);
@@ -2140,16 +2142,58 @@  static void btusb_notify(struct hci_dev *hdev, unsigned int evt)
 	}
 }
 
+static struct usb_host_interface *btusb_find_altsetting(struct btusb_data *data,
+							int alt)
+{
+	struct usb_interface *intf = data->isoc;
+	int i;
+
+	BT_DBG("Looking for Alt no :%d", alt);
+
+	if (!intf)
+		return NULL;
+
+	for (i = 0; i < intf->num_altsetting; i++) {
+		if (intf->altsetting[i].desc.bAlternateSetting == alt)
+			return &intf->altsetting[i];
+	}
+
+	return NULL;
+}
+
 static inline int __set_isoc_interface(struct hci_dev *hdev, int altsetting)
 {
 	struct btusb_data *data = hci_get_drvdata(hdev);
 	struct usb_interface *intf = data->isoc;
 	struct usb_endpoint_descriptor *ep_desc;
+	struct usb_host_interface *alt;
 	int i, err;
 
 	if (!data->isoc)
 		return -ENODEV;
 
+	/* For some Realtek chips, they actually have the altsetting 6, but its
+	 * altsetting descriptor is not exposed. We can activate altsetting 6 by
+	 * replacing the altsetting 5.
+	 */
+	if (altsetting == 6 && !btusb_find_altsetting(data, 6) &&
+	    btrealtek_test_flag(hdev, REALTEK_ALT6_FORCE)) {
+		alt = btusb_find_altsetting(data, 5);
+		if (alt) {
+			data->isoc_mps = 49;
+			for (i = 0; i < alt->desc.bNumEndpoints; i++) {
+				ep_desc = &alt->endpoint[i].desc;
+				if (!usb_endpoint_xfer_isoc(ep_desc))
+					continue;
+				data->isoc_mps =
+					le16_to_cpu(ep_desc->wMaxPacketSize);
+				ep_desc->wMaxPacketSize = cpu_to_le16(63);
+			}
+			alt->desc.bAlternateSetting = 6;
+			set_bit(BTUSB_ISOC_ALT_CHANGED, &data->flags);
+		}
+	}
+
 	err = usb_set_interface(data->udev, data->isoc_ifnum, altsetting);
 	if (err < 0) {
 		bt_dev_err(hdev, "setting interface failed (%d)", -err);
@@ -2161,6 +2205,22 @@  static inline int __set_isoc_interface(struct hci_dev *hdev, int altsetting)
 	data->isoc_tx_ep = NULL;
 	data->isoc_rx_ep = NULL;
 
+	/* Recover alt 5 desc if alt 0 is set. */
+	if (!altsetting && test_bit(BTUSB_ISOC_ALT_CHANGED, &data->flags)) {
+		alt = btusb_find_altsetting(data, 6);
+		if (alt) {
+			for (i = 0; i < alt->desc.bNumEndpoints; i++) {
+				ep_desc = &alt->endpoint[i].desc;
+				if (!usb_endpoint_xfer_isoc(ep_desc))
+					continue;
+				ep_desc->wMaxPacketSize =
+					cpu_to_le16(data->isoc_mps);
+			}
+			alt->desc.bAlternateSetting = 5;
+			clear_bit(BTUSB_ISOC_ALT_CHANGED, &data->flags);
+		}
+	}
+
 	for (i = 0; i < intf->cur_altsetting->desc.bNumEndpoints; i++) {
 		ep_desc = &intf->cur_altsetting->endpoint[i].desc;
 
@@ -2223,25 +2283,6 @@  static int btusb_switch_alt_setting(struct hci_dev *hdev, int new_alts)
 	return 0;
 }
 
-static struct usb_host_interface *btusb_find_altsetting(struct btusb_data *data,
-							int alt)
-{
-	struct usb_interface *intf = data->isoc;
-	int i;
-
-	BT_DBG("Looking for Alt no :%d", alt);
-
-	if (!intf)
-		return NULL;
-
-	for (i = 0; i < intf->num_altsetting; i++) {
-		if (intf->altsetting[i].desc.bAlternateSetting == alt)
-			return &intf->altsetting[i];
-	}
-
-	return NULL;
-}
-
 static void btusb_work(struct work_struct *work)
 {
 	struct btusb_data *data = container_of(work, struct btusb_data, work);
@@ -2279,7 +2320,8 @@  static void btusb_work(struct work_struct *work)
 			 * MTU >= 3 (packets) * 25 (size) - 3 (headers) = 72
 			 * see also Core spec 5, vol 4, B 2.1.1 & Table 2.1.
 			 */
-			if (btusb_find_altsetting(data, 6))
+			if (btusb_find_altsetting(data, 6) ||
+			    btrealtek_test_flag(hdev, REALTEK_ALT6_FORCE))
 				new_alts = 6;
 			else if (btusb_find_altsetting(data, 3) &&
 				 hdev->sco_mtu >= 72 &&