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Date:   Wed, 4 Oct 2023 14:46:09 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Max Chou <max.chou@realtek.com>
Cc:     Bagas Sanjaya <bagasdotme@gmail.com>,
        Hilda Wu <hildawu@realtek.com>,
        "alex_lu@realsil.com.cn" <alex_lu@realsil.com.cn>,
        Luiz Augusto von Dentz <luiz.von.dentz@intel.com>,
        Marcel Holtmann <marcel@holtmann.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Juerg Haefliger <juerg.haefliger@canonical.com>,
        Linux Bluetooth <linux-bluetooth@vger.kernel.org>,
        Thorsten Leemhuis <linux@leemhuis.info>,
        Linux Regressions <regressions@lists.linux.dev>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Regression: devcoredump patch broke Realtek usb bluetooth adapter
Message-ID: <20231004114609.dca6ebtmx37fsx5l@box.shutemov.name>
References: <20231003182038.k57nirtt4sonvt7c@box.shutemov.name>
 <ZRyqIn0_qqEFBPdy@debian.me>
 <b2ef2f1c457a4cf7a246b2e8b8598a30@realtek.com>
 <20231004044947.vgegwvxxindkjo7g@box.shutemov.name>
 <7507ad6c8a964b179bf2b3318104a124@realtek.com>
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On Wed, Oct 04, 2023 at 07:28:45AM +0000, Max Chou wrote:
> Hi! Kirill,
> I guess the root cause is as below.
> ===
> static int btrtl_register_devcoredump_support(struct hci_dev *hdev)
> {
>         int err;
> 
>         err = hci_devcd_register(hdev, btrtl_coredump, btrtl_dmp_hdr, NULL);
> 
>         return err;
> }
> ===
> If CONFIG_DEV_COREDUMP is not enabled, it would return -EOPNOTSUPP for hci_devcd_register().
> Unfortunately, btrtl_register_devcoredump_support() will return it. 
> Finally, -EOPNOSTUPP will be returned for btrtl_setup_realtek().
> 
> Could you have the following workaround for the root cause checked?
> Please share dmesg as well. Thanks,

Yes. It works and I see 

[    3.640539] Bluetooth: hci0: RTL: btrtl_register_devcoredump_support(): err = -95

in dmesg. -EOPNOTSUPP indeed.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov