linux-kernel - Re: [PATCH v9 7/7] Bluetooth: hci_qca: Add support for Qualcomm Bluetooth chip wcn3990

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Message-ID: <20180710163909.GQ129942@google.com>
Date:   Tue, 10 Jul 2018 09:39:09 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Balakrishna Godavarthi <bgodavar@...eaurora.org>
Cc:     marcel@...tmann.org, johan.hedberg@...il.com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, thierry.escande@...aro.org,
        rtatiya@...eaurora.org, hemantg@...eaurora.org,
        linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>
Subject: Re: [PATCH v9 7/7] Bluetooth: hci_qca: Add support for Qualcomm
 Bluetooth chip wcn3990

Hi Bala,

On Tue, Jul 10, 2018 at 06:22:02PM +0530, Balakrishna Godavarthi wrote:
> Hi Matthias,
> 
> On 2018-07-07 03:51, Matthias Kaehlcke wrote:
> > On Thu, Jul 05, 2018 at 10:25:15PM +0530, Balakrishna Godavarthi wrote:
> > > +	 * sending vendor power on and off pulse to SoC.
> > > +	 */
> > 
> > The function is called qca_send_vendor_cmd(), the comment about power
> > on/off pulses seems misplaced here. Are there other 'vendor commands'
> > that require a different flow control behavior?
> > 
> > Perhaps the function should have a different name or we need another
> > wrapper.
> > 
> 
> [Bala]: this function is used to send single byte vendor commands. like
> power on and off pulse.
>         and all single byte vendor commands require an flow control off and
> on.
>         so might be function name change is required.
>         instead of qca_send_vendor_cmd(). i want to change function name to
> qca_send_pulse() as this will be generic.

'pulse' covers power on/off pulses, is it also applicable to other
single byte commands? How are these commands named in the QCA
documentation?

In any case the comment about 'vendor power on and off pulse' should
be updated to refer to 'vendor commands'/'pulses' or whatever
terminology we decide to use.

> > > +	hci_uart_set_flow_control(hu, true);
> > 
> > Should the changing of the flow control be limited to wcn3990? As of
> > now the function is only called for wcn3990, however this is not
> > stated as a requirement and might change in the future.
> > 
> > > +	skb_put_u8(skb, cmd);
> > > +	hci_skb_pkt_type(skb) = HCI_COMMAND_PKT;
> > > +
> > > +	skb_queue_tail(&qca->txq, skb);
> > > +	hci_uart_tx_wakeup(hu);
> > > +
> > > +	/* Wait for 100 uS for SoC to settle down */
> > > +	usleep_range(100, 200);
> > 
> > Is this needed for any 'vendor command' or directly related with the
> > power on/off pulses?
> > 
> 
> [Bala] : flow control  off/on is needed for power on and off pulses along
> with
>          command to set baudrate.. this is common across all the present
> chips and chips which are in development stages.
>          might be function name is confusing will update the function name.

The current name *might* be ok, depending on if we come up with
something better. If the QCA docs refer to them as 'vendor commands'
and there are no other multi-byte 'vendor commands' I'm fine with it.

Is the settling down of 100us specific to the power on/off pulses or
also applicable to other commands?

Thanks

Matthias