linux-kernel - Re: [PATCH v4 3/4] Bluetooth: hci

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Date:   Wed, 13 Nov 2019 22:03:41 -0800
From:   Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
To:     Marcel Holtmann <marcel@...tmann.org>
Cc:     Johan Hedberg <johan.hedberg@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        linux-bluetooth@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/4] Bluetooth: hci_bcm: Support pcm params in dts

On Wed, Nov 13, 2019 at 9:29 PM Marcel Holtmann <marcel@...tmann.org> wrote:
>
> Hi Abhishek,
>
> >>> BCM chips may require configuration of PCM to operate correctly and
> >>> there is a vendor specific HCI command to do this. Add support in the
> >>> hci_bcm driver to parse this from devicetree and configure the chip.
> >>>
> >>> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> >>> ---
> >>>
> >>> Changes in v4: None
> >>> Changes in v3: None
> >>> Changes in v2: None
> >>>
> >>> drivers/bluetooth/hci_bcm.c | 32 ++++++++++++++++++++++++++++++++
> >>> 1 file changed, 32 insertions(+)
> >>>
> >>> diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
> >>> index 6134bff58748..4ee0b45be7e2 100644
> >>> --- a/drivers/bluetooth/hci_bcm.c
> >>> +++ b/drivers/bluetooth/hci_bcm.c
> >>> @@ -88,6 +88,8 @@ struct bcm_device_data {
> >>> *    used to disable flow control during runtime suspend and system sleep
> >>> * @is_suspended: whether flow control is currently disabled
> >>> * @disallow_set_baudrate: don't allow set_baudrate
> >>> + * @has_pcm_params: whether PCM parameters need to be configured
> >>> + * @pcm_params: PCM and routing parameters
> >>> */
> >>> struct bcm_device {
> >>>      /* Must be the first member, hci_serdev.c expects this. */
> >>> @@ -122,6 +124,9 @@ struct bcm_device {
> >>>      bool                    is_suspended;
> >>> #endif
> >>>      bool                    disallow_set_baudrate;
> >>> +
> >>> +     bool                            has_pcm_params;
> >>> +     struct bcm_set_pcm_int_params   pcm_params;
> >>> };
> >>>
> >>> /* generic bcm uart resources */
> >>> @@ -596,6 +601,16 @@ static int bcm_setup(struct hci_uart *hu)
> >>>                      host_set_baudrate(hu, speed);
> >>>      }
> >>>
> >>> +     /* PCM parameters if any*/
> >>> +     if (bcm->dev && bcm->dev->has_pcm_params) {
> >>> +             err = btbcm_set_pcm_int_params(hu->hdev, &bcm->dev->pcm_params);
> >>> +
> >>> +             if (err) {
> >>> +                     bt_dev_info(hu->hdev, "BCM: Set pcm params failed (%d)",
> >>> +                                 err);
> >>> +             }
> >>> +     }
> >>> +
> >>> finalize:
> >>>      release_firmware(fw);
> >>>
> >>> @@ -1132,7 +1147,24 @@ static int bcm_acpi_probe(struct bcm_device *dev)
> >>>
> >>> static int bcm_of_probe(struct bcm_device *bdev)
> >>> {
> >>> +     int err;
> >>> +
> >>>      device_property_read_u32(bdev->dev, "max-speed", &bdev->oper_speed);
> >>> +
> >>> +     err = device_property_read_u8(bdev->dev, "brcm,bt-sco-routing",
> >>> +                                   &bdev->pcm_params.routing);
> >>> +     if (!err)
> >>> +             bdev->has_pcm_params = true;
> >>
> >> I think in case of HCI as routing path, these should be using the default or zero values as defined by Broadcom.
> >
> > I'm not sure what these default values should be. Wouldn't it be
> > reasonable to expect the user/developer to set the various brcm
> > parameters in device tree?
> > If unset, it's just 0.
>
> if that works with the hardware I am fine with that. The other option is to actually first read the current values. And then only change the ones that are supplied by the DT.

I don't know of a read pcm params command (this would be nice to have).

I think it might be prudent to default the frame_mode and clock_mode
to master (0x1). I'll test how the hardware responds to 0x0 and update
the default to 0x1 if things fail badly.

>
> Regards
>
> Marcel
>