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Date:   Wed, 13 Mar 2019 17:43:14 +0800
From:   rjliao@codeaurora.org
To:     Matthias Kaehlcke <mka@chromium.org>
Cc:     Balakrishna Godavarthi <bgodavar@codeaurora.org>,
        marcel@holtmann.org, johan.hedberg@gmail.com,
        linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
        hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH v1] Bluetooth: hci_qca: Enable the ldisc for ROME for x86
 platforms.
In-Reply-To: <20190312155241.GB200579@google.com>
References: <20190307101722.25871-1-bgodavar@codeaurora.org>
 <20190307204224.GD138592@google.com>
 <6e0abe10b3ed44053e92ad6a21c75d93@codeaurora.org>
 <20190308185232.GB69116@google.com>
 <1042d21dde881e886541d32b8f0dff63@codeaurora.org>
 <20190312155241.GB200579@google.com>
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在 2019-03-12 23:52，Matthias Kaehlcke 写道：
> Hi Rocky,
> 
> On Tue, Mar 12, 2019 at 05:01:59PM +0800, rjliao@codeaurora.org wrote:
>> 在 2019-03-09 02:52，Matthias Kaehlcke 写道：
>> > On Fri, Mar 08, 2019 at 10:43:14AM +0530, Balakrishna Godavarthi wrote:
>> > > Hi Matthias,
>> > >
>> > > On 2019-03-08 02:12, Matthias Kaehlcke wrote:
>> > > > Hi Balakrishna,
>> > > >
>> > > > On Thu, Mar 07, 2019 at 03:47:22PM +0530, Balakrishna Godavarthi wrote:
>> > > > > When using btattach to setup Rome over ldisc we observed a crash
>> > > > > in qca_setup as it will try to access the serdev which is not
>> > > > > available in the ldisc proto. This patch will fix the crash by
>> > > > > support both the ldisc and serdev way in the qca hci_uart driver.
>> > > > >
>> > > > > Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
>> > > >
>> > > > Oh, I wasn't aware of the instantiation through ldisc and was actually
>> > > > considering to *remove* some of the seemingly unnecessary serdev
>> > > > checks.
>> > > >
>> > > > > ---
>> > > > >  drivers/bluetooth/hci_qca.c | 47
>> > > > > ++++++++++++++++++++++---------------
>> > > > >  1 file changed, 28 insertions(+), 19 deletions(-)
>> > > > >
>> > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
>> > > > > index 237aea34b69f..0a5c98d46864 100644
>> > > > > --- a/drivers/bluetooth/hci_qca.c
>> > > > > +++ b/drivers/bluetooth/hci_qca.c
>> > > > > @@ -963,7 +963,7 @@ static int qca_set_baudrate(struct hci_dev
>> > > > > *hdev, uint8_t baudrate)
>> > > > >  {
>> > > > >  	struct hci_uart *hu = hci_get_drvdata(hdev);
>> > > > >  	struct qca_data *qca = hu->priv;
>> > > > > -	struct qca_serdev *qcadev;
>> > > > > +	struct qca_serdev *qcadev = NULL;
>> > > >
>> > > > In many cases the only field that is accessed is qcadev->btsoc_type. I
>> > > > think something like 'qca_get_soc_type(struct hci_dev *hdev / struct
>> > > > hci_uart *hu)' would make things more readable.
>> > > >
>> > > [Bala]: sure will update this in other patch once this change is
>> > > landed as
>> > > this has to
>> > >         go in priority as we have crash coming.
>> >
>> > That's not how things should work, especially for fairly trivial
>> > changes. It requires reviewers to first spent time to review the patch
>> > that adds clutter and later spend more time to review the one that
>> > removes it. It's also easier to get a clean patch merged in the first
>> > place, rather than a noisy one.
>> >
>> > Anyway, here is my take at it:
>> > https://lore.kernel.org/patchwork/patch/1049014/
>> >
>> > Please help with testing for ROME, unless you disagree with the
>> > approach.
>> >
>> > Thanks
>> >
>> > Matthias
>> 
>> Hi Matthias,
>> 
>> I will test your patch and update to you, and you are correct that 
>> AR3002 is
>> not part of Rome family, you should use QCA_ROME as the default return 
>> of
>> qca_soc_type.
> 
> Thanks for the confirmation!
> 
>> Could you also loop me in
>> https://lore.kernel.org/patchwork/patch/1049014/?
> 
> This patch has been superseded by a newer version:
> 
> https://lore.kernel.org/patchwork/patch/1049696/
> 
> It already landed in bluetooth-next.
> 
> Testing with Rome and ldisc would still be appreciated, since I don't
> have such a configuration.
> 
> Thanks
> 
> Matthias

Hi Matthias,

I verified your change and found there is another deference to serdev in 
the qca_set_baudrate() function while running the ldisc proto, it will 
cause a crash and need to add a check as below. Could you help to add 
this change?

<       serdev_device_wait_until_sent(hu->serdev,
<                       msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS));
---
>       if (hu->serdev)
>               serdev_device_wait_until_sent(hu->serdev,
>                               msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS));