linux-kernel - Re: [PATCH v1 3/4] Bluetooth: hci_qca: clear HCI_QUIRK_RESET_ON

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Date:   Wed, 14 Nov 2018 12:20:39 +0530
From:   Balakrishna Godavarthi <bgodavar@...eaurora.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        open list <linux-kernel@...r.kernel.org>,
        linux-bluetooth@...r.kernel.org, hemantg@...eaurora.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v1 3/4] Bluetooth: hci_qca: clear HCI_QUIRK_RESET_ON_CLOSE
 flag

Hi Matthias,

On 2018-11-14 07:44, Matthias Kaehlcke wrote:
> On Tue, Nov 06, 2018 at 06:44:07PM +0530, Balakrishna Godavarthi wrote:
>> Hi Marcel,
>> 
>> On 2018-11-06 18:32, Marcel Holtmann wrote:
>> > Hi Balakrishna,
>> >
>> > > > > During hci down we are sending reset command to chip, which
>> > > > > is not required for wcn3990, as hdev->shutdown() will turn off the
>> > > > > regulators.
>> > > > > Signed-off-by: Balakrishna Godavarthi <bgodavar@...eaurora.org>
>> > > > > ---
>> > > > > drivers/bluetooth/hci_qca.c | 1 +
>> > > > > 1 file changed, 1 insertion(+)
>> > > > > diff --git a/drivers/bluetooth/hci_qca.c
>> > > > > b/drivers/bluetooth/hci_qca.c
>> > > > > index 8301663f0004..97b57e0f4725 100644
>> > > > > --- a/drivers/bluetooth/hci_qca.c
>> > > > > +++ b/drivers/bluetooth/hci_qca.c
>> > > > > @@ -1190,6 +1190,7 @@ static int qca_setup(struct hci_uart *hu)
>> > > > > 		 */
>> > > > > 		set_bit(HCI_QUIRK_NON_PERSISTENT_SETUP, &hdev->quirks);
>> > > > > 		set_bit(HCI_QUIRK_USE_BDADDR_PROPERTY, &hdev->quirks);
>> > > > > +		clear_bit(HCI_QUIRK_RESET_ON_CLOSE, &hdev->quirks);
> 
> This patch doesn't apply cleanly against bluetooth-next, looks like
> you have the unrelated "Bluetooth: hci_qca: Set
> HCI_QUIRK_USE_BDADDR_PROPERTY for wcn3990"
> (https://lore.kernel.org/patchwork/patch/1004372/) in your tree.
> 
[Bala]: this patch is on top of 
https://lore.kernel.org/patchwork/patch/1004372/.
         will remove the dependency and update the patch.

>> > > > > 		hu->hdev->shutdown = qca_power_off;
>> > > > > 		ret = qca_wcn3990_init(hu);
>> > > > > 		if (ret)
>> > > > I am pretty certain that you didn’t want this quirk:
>> > > >        /* When this quirk is set, the HCI Reset command is send when
>> > > >         * closing the transport instead of when opening it.
>> > > > This quirk is for Bluetooth 1.0b devices where the HCI_Reset behavior
>> > > > was not clear or for devices that actually misbehave with the initial
>> > > > HCI_Reset.
>> > > > In addition, you commit message is totally misleading. That is not
>> > > > what is happening with this quirk.
>> > > > Regards
>> > > > Marcel
>> > >
>> > > My intention was reset command is not required when we do an hci down.
>> > > this is because of hdev->shutdown will turn off the regulators.
>> > > It is like turning off the chip. sending reset command after turning
>> > > off the chip is not required.
>> > >
>> > > I understand the usage of the quirk, will update the commit text.
>> >
>> > you are papering over the issue. Actually
>> > hci_serdev.c:hci_uart_register_device() is the culprit with the legacy
>> > code copied over from hci_ldisc.c:hci_uart_register_dev(). I think
>> > there is no point doing all this legacy line discipline quirk handling
>> > until it is really needed. The serdev drivers are all for recent
>> > hardware.
>> >
>> > That said, having moved over to a btuart.c approach and killed the
>> > whole hci_serdev.c thing would have been a lot better here. You will
>> > keep running in weird situations where 18 year old code keeps
>> > surprising you.
>> 
>> [Bala]: even i feel the same. they are lot such kind of HACK's we need 
>> to do
>> with current arch.
>>         when can we expect btuart.c merged to bt-next. i think having 
>> btuart
>> will helps us to have the control of
>>         vendor porto's call's like in btusb.c
> 
> btuart was initially part of the 'add support for Bluetooth on MT7622
> SoC' series (https://lore.kernel.org/patchwork/patch/960806/), but was
> dropped with v6
> (https://lore.kernel.org/patchwork/project/lkml/list/?series=360046)
> upon Marcel's request: 'Frankly I prefer to keep the btuart.c driver
> for drivers that really just use H:4 as transport protocol. If the
> protocol is only H:4 alike and has extra headers, then it should be a
> separate driver.' 
> (https://lore.kernel.org/patchwork/patch/960806/#1148426).
> 
> Cheers
> 
> Matthias

[Bala]: currently our main moto is to make this driver to be stable for 
both rome and wcn3990.
         we will look into working on btuart.c type driver for future 
qualcomm BT devices.

-- 
Regards
Balakrishna.