linux-kernel - Re: [PATCH v6 2/4] Bluetooth: btbcm: Support pcm configuration

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Date:   Tue, 19 Nov 2019 12:48:40 -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 v6 2/4] Bluetooth: btbcm: Support pcm configuration

On Mon, Nov 18, 2019 at 9:35 PM Marcel Holtmann <marcel@...tmann.org> wrote:
>
> Hi Abhishek,
>
> > Add BCM vendor specific command to configure PCM parameters. The new
> > vendor opcode allows us to set the sco routing, the pcm interface rate,
> > and a few other pcm specific options (frame sync, sync mode, and clock
> > mode). See broadcom-bluetooth.txt in Documentation for more information
> > about valid values for those settings.
> >
> > Here is an example trace where this opcode was used to configure
> > a BCM4354:
> >
> >        < HCI Command: Vendor (0x3f|0x001c) plen 5
> >                01 02 00 01 01
> >> HCI Event: Command Complete (0x0e) plen 4
> >        Vendor (0x3f|0x001c) ncmd 1
> >                Status: Success (0x00)
> >
> > We can read back the values as well with ocf 0x001d to confirm the
> > values that were set:
> >        $ hcitool cmd 0x3f 0x001d
> >        < HCI Command: ogf 0x3f, ocf 0x001d, plen 0
> >> HCI Event: 0x0e plen 9
> >        01 1D FC 00 01 02 00 01 01
> >
> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> > ---
> >
> > Changes in v6: None
> > Changes in v5: None
> > Changes in v4: None
> > Changes in v3: None
> > Changes in v2: None
> >
> > drivers/bluetooth/btbcm.c | 47 +++++++++++++++++++++++++++++++++++++++
> > drivers/bluetooth/btbcm.h | 16 +++++++++++++
> > 2 files changed, 63 insertions(+)
> >
> > diff --git a/drivers/bluetooth/btbcm.c b/drivers/bluetooth/btbcm.c
> > index 2d2e6d862068..df90841d29c5 100644
> > --- a/drivers/bluetooth/btbcm.c
> > +++ b/drivers/bluetooth/btbcm.c
> > @@ -105,6 +105,53 @@ int btbcm_set_bdaddr(struct hci_dev *hdev, const bdaddr_t *bdaddr)
> > }
> > EXPORT_SYMBOL_GPL(btbcm_set_bdaddr);
> >
> > +int btbcm_read_pcm_int_params(struct hci_dev *hdev,
> > +                           struct bcm_set_pcm_int_params *int_params)
> > +{
>
> the name should be _param and not _params since if I remember correctly that is how Broadcom specified it. Also just use param as variable name.

Technically, you are configuring multiple PCM params :)

>
> > +     struct sk_buff *skb;
> > +     int err = 0;
> > +
> > +     skb = __hci_cmd_sync(hdev, 0xfc1d, 5, int_params, HCI_INIT_TIMEOUT);
> > +     if (IS_ERR(skb)) {
> > +             err = PTR_ERR(skb);
> > +             bt_dev_err(hdev, "BCM: Read PCM int params failed (%d)", err);
> > +             return err;
> > +     }
> > +
> > +     if (!skb->data[0] && skb->len == sizeof(*int_params) + 1) {
> > +             memcpy(int_params, &skb->data[1], sizeof(*int_params));
> > +     } else {
> > +             bt_dev_err(hdev,
> > +                        "BCM: Read PCM int params failed (%d), Length (%d)",
> > +                        skb->data[0], skb->len);
> > +             err = -EINVAL;
> > +     }
> > +
> > +     kfree_skb(skb);
>
> I find these harder to read actually and it can be still fault at data[0] access.
>
>         if (skb->len != sizeof(*param) || skb->data[0]) {
>                 bt_dev_err(hdev, "BCM: Read SCO PCM int parameter failure");
>                 kfree_skb(skb);
>                 return -EIO;
>         }
>
>         memcpy(param, skb->data + 1, sizeof(*param));
>         kfree_skb(skb);
>         return 0;
> }
>

Sure. skb->len should be sizeof(*param) + 1 because there's an extra
byte for the status as well.

> > +
> > +     return err;
> > +}
> > +EXPORT_SYMBOL_GPL(btbcm_read_pcm_int_params);
> > +
> > +int btbcm_write_pcm_int_params(struct hci_dev *hdev,
> > +                            const struct bcm_set_pcm_int_params *int_params)
> > +{
> > +     struct sk_buff *skb;
> > +     int err;
> > +
> > +     /* Vendor ocf 0x001c sets the pcm parameters and 0x001d reads it */
>
> Scrap this comment.
>
> > +     skb = __hci_cmd_sync(hdev, 0xfc1c, 5, int_params, HCI_INIT_TIMEOUT);
> > +     if (IS_ERR(skb)) {
> > +             err = PTR_ERR(skb);
> > +             bt_dev_err(hdev, "BCM: Write PCM int params failed (%d)", err);
> > +             return err;
> > +     }
> > +     kfree_skb(skb);
> > +
> > +     return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(btbcm_write_pcm_int_params);
> > +
> > int btbcm_patchram(struct hci_dev *hdev, const struct firmware *fw)
> > {
>
> Otherwise this looks good.
>
> Regards
>
> Marcel
>

So generally, I've done a whole new patch series with every change.
Would you prefer to see singular updates on the same email thread or
should I keep doing new patch series?