From: Balakrishna Godavarthi <bgodavar@codeaurora.org>
To: Johan Hovold <johan@kernel.org>
Cc: marcel@holtmann.org, johan.hedberg@gmail.com, mka@chromium.org,
linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org,
Johan Hovold <jhovold@gmail.com>
Subject: Re: [PATCH v4 1/5] Bluetooth: hci_qca: use wait_until_sent() for power pulses
Date: Tue, 18 Dec 2018 16:25:30 +0530 [thread overview]
Message-ID: <854e80111cbcb8a23a9e1e486328eb8f@codeaurora.org> (raw)
In-Reply-To: <20181218091306.GA10562@localhost>
Hi Johan,
On 2018-12-18 14:43, Johan Hovold wrote:
> On Mon, Dec 17, 2018 at 07:43:26PM +0530, Balakrishna Godavarthi wrote:
>> wcn3990 requires a power pulse to turn ON/OFF along with
>> regulators. Sometimes we are observing the power pulses are sent
>> out with some time delay, due to queuing these commands. This is
>> causing synchronization issues with chip, which intern delay the
>> chip setup or may end up with communication issues.
>>
>> Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
>> ---
>> v4:
>> * used serdev_device_write_buf() instead of serdev_device_write()
>>
>> v3:
>> * no change.
>> v2:
>> * Updated function qca_send_power_pulse()
>> * addressed reviewer comments.
>>
>> v1:
>> * initial patch
>>
>> ---
>> drivers/bluetooth/hci_qca.c | 37
>> +++++++++++++------------------------
>> 1 file changed, 13 insertions(+), 24 deletions(-)
>>
>> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
>> index f036c8f98ea3..d8bc77c8c9b9 100644
>> --- a/drivers/bluetooth/hci_qca.c
>> +++ b/drivers/bluetooth/hci_qca.c
>> @@ -1013,11 +1013,9 @@ static inline void host_set_baudrate(struct
>> hci_uart *hu, unsigned int speed)
>> hci_uart_set_baudrate(hu, speed);
>> }
>>
>> -static int qca_send_power_pulse(struct hci_dev *hdev, u8 cmd)
>> +static int qca_send_power_pulse(struct hci_uart *hu, u8 cmd)
>> {
>> - struct hci_uart *hu = hci_get_drvdata(hdev);
>> - struct qca_data *qca = hu->priv;
>> - struct sk_buff *skb;
>> + int ret;
>>
>> /* These power pulses are single byte command which are sent
>> * at required baudrate to wcn3990. On wcn3990, we have an external
>> @@ -1029,19 +1027,16 @@ static int qca_send_power_pulse(struct hci_dev
>> *hdev, u8 cmd)
>> * save power. Disabling hardware flow control is mandatory while
>> * sending power pulses to SoC.
>> */
>> - bt_dev_dbg(hdev, "sending power pulse %02x to SoC", cmd);
>> -
>> - skb = bt_skb_alloc(sizeof(cmd), GFP_KERNEL);
>> - if (!skb)
>> - return -ENOMEM;
>> -
>> + bt_dev_dbg(hu->hdev, "sending power pulse %02x to SoC", cmd);
>> hci_uart_set_flow_control(hu, true);
>> + ret = serdev_device_write_buf(hu->serdev, &cmd, sizeof(cmd));
>> + if (ret < 0) {
>> + bt_dev_err(hu->hdev, "failed to send power pulse %02x to SoC",
>> + cmd);
>> + return ret;
>> + }
>
> As I mentioned earlier, serdev_device_write_buf() can buffer less than
> sizeof(cmd) bytes if the tty driver's write buffer is full (and return
> the number of bytes buffered).
>
> How you want to deal with that is up to you and the bluetooth
> maintainers, but I think you want to at least log it even if you choose
> to ignore it.
>
> Johan
[Bala]: thanks for reminding me for buffer size.
we use the qca_send_power_pulse() where we use
serdev_write_buf() to send
a single byte commands to the chip during power ON or power OFF
i.e. as soon as we open port or before close.
during power on:
ideally open port can guarantee me to the have tty buffer empty
as we didn't queued any data.
let us assume that if the buffer is full(),
serdev_device_write_buf() will return -1 (as buffer is full)
anyways i have check for return status to log the write_buf
failure.
during power off:
yes here we may face an issue as already we have some data
queued in the buffer. i.e. due to previous transactions.
I think we can achieve this by calling
serdev_device_write_flush() and then calling serdev_device_write_buf().
--
Regards
Balakrishna.
next prev parent reply other threads:[~2018-12-18 10:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-17 14:13 [PATCH v4 0/5] Bug fixes for Qualcomm BT chip wcn3990 Balakrishna Godavarthi
2018-12-17 14:13 ` [PATCH v4 1/5] Bluetooth: hci_qca: use wait_until_sent() for power pulses Balakrishna Godavarthi
2018-12-18 9:13 ` Johan Hovold
2018-12-18 10:55 ` Balakrishna Godavarthi [this message]
2018-12-17 14:13 ` [PATCH v4 2/5] Bluetooth: hci_qca: Deassert RTS while baudrate change command Balakrishna Godavarthi
2018-12-17 14:13 ` [PATCH v4 3/5] Bluetooth: hci_qca: Fix frame reassembly errors for wcn3990 Balakrishna Godavarthi
2018-12-17 14:13 ` [PATCH v4 4/5] Bluetooth: hci_qca: Disable IBS state machine and flush Tx buffer Balakrishna Godavarthi
2018-12-17 14:13 ` [PATCH v4 5/5] Bluetooth: btqca: inject command complete event during fw download Balakrishna Godavarthi
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