Re: [PATCH] wifi: rtw89: retry efuse physical map dump on transient failure

[Christian Hewitt <christianshewitt@gmail.com>]

> On 16 Mar 2026, at 9:32 am, Ping-Ke Shih <pkshih@realtek.com> wrote:
> 
> Christian Hewitt <christianshewitt@gmail.com> wrote:
>> On Radxa Rock 5B with a RTL8852BE combo WiFi/BT card, the efuse
>> physical map dump intermittently fails with -EBUSY during probe.
>> The failure occurs in rtw89_dump_physical_efuse_map_ddv() where
>> read_poll_timeout_atomic() times out waiting for the B_AX_EF_RDY
>> bit after 1 second.
>> 
>> The root cause is a timing race during boot: the WiFi driver's
>> chip initialization (firmware download via PCIe) overlaps with the
>> Bluetooth firmware download to the same combo chip over USB. This
>> can leave the efuse controller temporarily unavailable when the
>> WiFi driver attempts to read the efuse map.
>> 
>> Add a retry loop (up to 3 attempts with 500ms delays) around the
>> physical efuse map dump in rtw89_parse_efuse_map_ax(). The firmware
>> download path already retries up to 5 times, but the efuse read
>> that follows has no retry logic, making it the weak link in the
>> probe sequence.
> 
> I'd prefer adding a wrapper to retry 5 times without delay as bottom
> changes for reference. If you want to limit retry only for
> 'dav == false' case, it is also fine to me.
> 
>> 
>> Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
> 
> [...]
> 
>> 
>> drivers/net/wireless/realtek/rtw89/efuse.c | 13 ++++++++++++-
>> 1 file changed, 12 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/net/wireless/realtek/rtw89/efuse.c
>> b/drivers/net/wireless/realtek/rtw89/efuse.c
>> index a2757a88d55d..d506f04ffd6c 100644
>> --- a/drivers/net/wireless/realtek/rtw89/efuse.c
>> +++ b/drivers/net/wireless/realtek/rtw89/efuse.c
>> @@ -270,6 +270,7 @@ int rtw89_parse_efuse_map_ax(struct rtw89_dev *rtwdev)
>>        u8 *log_map = NULL;
>>        u8 *dav_phy_map = NULL;
>>        u8 *dav_log_map = NULL;
>> +       int retry;
>>        int ret;
>> 
>>        if (rtw89_read16(rtwdev, R_AX_SYS_WL_EFUSE_CTRL) & B_AX_AUTOLOAD_SUS)
>> @@ -289,7 +290,17 @@ int rtw89_parse_efuse_map_ax(struct rtw89_dev *rtwdev)
>>                goto out_free;
>>        }
>> 
>> -       ret = rtw89_dump_physical_efuse_map(rtwdev, phy_map, 0, phy_size,
>> false);
>> +       for (retry = 0; retry < 3; retry++) {
>> +               if (retry) {
>> +                       rtw89_warn(rtwdev, "efuse dump failed, retrying
>> (%d)\n",
>> +                                  retry);
>> +                       fsleep(500000);
>> +               }
>> +               ret = rtw89_dump_physical_efuse_map(rtwdev, phy_map, 0,
>> +                                                   phy_size, false);
>> +               if (!ret)
>> +                       break;
>> +       }
>>        if (ret) {
>>                rtw89_warn(rtwdev, "failed to dump efuse physical map\n");
>>                goto out_free;
>> --
>> 2.43.0
> 
> How about retrying 5 times without fsleep(500000)?
> 
> diff --git a/drivers/net/wireless/realtek/rtw89/efuse.c b/drivers/net/wireless/realtek/rtw89/efuse.c
> index a2757a88d55d..89d4b1b865f8 100644
> --- a/drivers/net/wireless/realtek/rtw89/efuse.c
> +++ b/drivers/net/wireless/realtek/rtw89/efuse.c
> @@ -185,8 +185,8 @@ static int rtw89_dump_physical_efuse_map_dav(struct rtw89_dev *rtwdev, u8 *map,
>        return 0;
> }
> 
> -static int rtw89_dump_physical_efuse_map(struct rtw89_dev *rtwdev, u8 *map,
> -                                        u32 dump_addr, u32 dump_size, bool dav)
> +static int __rtw89_dump_physical_efuse_map(struct rtw89_dev *rtwdev, u8 *map,
> +                                          u32 dump_addr, u32 dump_size, bool dav)
> {
>        int ret;
> 
> @@ -208,6 +208,25 @@ static int rtw89_dump_physical_efuse_map(struct rtw89_dev *rtwdev, u8 *map,
>        return 0;
> }
> 
> +static int rtw89_dump_physical_efuse_map(struct rtw89_dev *rtwdev, u8 *map,
> +                                        u32 dump_addr, u32 dump_size, bool dav)
> +{
> +       int retry;
> +       int ret;
> +
> +       for (retry = 0; retry < 5; retry++) {
> +               ret = __rtw89_dump_physical_efuse_map(rtwdev, map, dump_addr,
> +                                                     dump_size, dav);
> +               if (!ret)
> +                       return 0;
> +
> +               rtw89_warn(rtwdev, "efuse dump (dav=%d) failed, retrying (%d)\n",
> +                          dav, retry);
> +       }
> +
> +       return ret;
> +}
> +
> #define invalid_efuse_header(hdr1, hdr2) \
>        ((hdr1) == 0xff || (hdr2) == 0xff)
> #define invalid_efuse_content(word_en, i) \

I’ve run some boot tests and this also resolves my efuse map use-case, e.g.

ROCK5B:~ # dmesg | grep rtw89
[    6.506375] rtw89_8852be 0002:21:00.0: loaded firmware rtw89/rtw8852b_fw-1.bin
[    6.506539] rtw89_8852be 0002:21:00.0: enabling device (0000 -> 0003)
[    6.516069] rtw89_8852be 0002:21:00.0: Firmware version 0.29.29.15 (6fb3ec41), cmd version 0, type 5
[    6.516083] rtw89_8852be 0002:21:00.0: Firmware version 0.29.29.15 (6fb3ec41), cmd version 0, type 3
[   10.153731] rtw89_8852be 0002:21:00.0: efuse dump (dav=0) failed, retrying (0)
[   10.405347] rtw89_8852be 0002:21:00.0: chip info CID: 0, CV: 1, AID: 0, ACV: 1, RFE: 1
[   10.408311] rtw89_8852be 0002:21:00.0: rfkill hardware state changed to enable

So far I haven’t observed more than 1x retry being required, and there are no
issues with loading the BT module.

Would you like me to send a v2 using your revised version? - or?

Christian