Date:   Wed, 13 Mar 2019 16:56:18 -0700
From:   Matthias Kaehlcke <mka@chromium.org>
To:     rjliao@codeaurora.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.
Message-ID: <20190313235618.GA112750@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>
 <a99bdc7679c9220a913dfa3e149757fa@codeaurora.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <a99bdc7679c9220a913dfa3e149757fa@codeaurora.org>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

On Wed, Mar 13, 2019 at 05:43:14PM +0800, rjliao@codeaurora.org wrote:
> 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));

argh, I shouldn't have missed this, thanks for testing!

Here is a fix:

https://lore.kernel.org/patchwork/patch/1050594/