Re: [PATCH 3/3] Bluetooth: btrtl: Skip initialization if firmware is already loaded

[Daniel Drake <drake@endlessm.com>]

On Thu, Jan 24, 2019 at 11:23 PM Kai-Heng Feng
<kai.heng.feng@canonical.com> wrote:
> Realtek bluetooth may not work after reboot:
> [   12.446130] Bluetooth: hci0: RTL: rtl: unknown IC info, lmp subver a99e, hci rev 826c, hci ver 0008
>
> The power is not cut during system reboot, so the firmware is kept in
> Bluetooth controller.
>
> Realtek bluetooth doesn't have the ability to check firmware loading
> status. but the version queried by HCI_OP_READ_LOCAL_VERSION will be
> different if firmware is already loaded. Realtek's own fork, rtk_btusb
> also use this method to detect the loading status.
>
> So let's assume the firmware is already loaded when we can't find
> matching IC info.

This logic was already present in the driver - but it looks like this
regressed at this point:

commit 26503ad25de8c7c93a2037f919c2e49a62cf65f1
Author: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date:   Thu Aug 2 16:57:13 2018 +0200

    Bluetooth: btrtl: split the device initialization into smaller parts

After your patch it is effectively there in two places now, since it
is also in btrtl_download_firmware() (although not really effective
after the above commit). I wonder if that can be cleaned up to avoid
duplication.

Regarding the other patches that move away from the style of returning
either a useful value or an error, is this purely a stylistic thing or
is it needed for your 3rd patch? I don't have strong feelings either
way but I have the impression that the currently implemented approach
is a common style within kernel code and I don't see benefit in
splitting off a separate out parameter.

Daniel


> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201921
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>  drivers/bluetooth/btrtl.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/bluetooth/btrtl.c b/drivers/bluetooth/btrtl.c
> index c36f500d8313..e2f89d57dd14 100644
> --- a/drivers/bluetooth/btrtl.c
> +++ b/drivers/bluetooth/btrtl.c
> @@ -546,9 +546,10 @@ int btrtl_initialize(struct hci_dev *hdev,
>                                             hdev->bus);
>
>         if (!btrtl_dev->ic_info) {
> -               rtl_dev_err(hdev, "rtl: unknown IC info, lmp subver %04x, hci rev %04x, hci ver %04x",
> -                           lmp_subver, hci_rev, hci_ver);
> -               return -EINVAL;
> +               rtl_dev_info(hdev, "rtl: unknown IC info, lmp subver %04x, hci rev %04x, hci ver %04x",
> +                            lmp_subver, hci_rev, hci_ver);
> +               rtl_dev_info(hdev, "rtl: firmware may be already loaded, or it's an unsupported IC.");
> +               return 0;
>         }
>
>         if (btrtl_dev->ic_info->has_rom_version) {
> @@ -621,7 +622,8 @@ int btrtl_setup_realtek(struct hci_dev *hdev)
>         if (ret)
>                 return ret;
>
> -       ret = btrtl_download_firmware(hdev, &btrtl_dev);
> +       if (btrtl_dev.ic_info)
> +               ret = btrtl_download_firmware(hdev, &btrtl_dev);
>
>         return ret;
>  }
> --
> 2.17.1
>