linux-kernel - Re: [PATCH 2/3] Bluetooth: hci_qca: Skip serdev wait when no transfer is pending

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Message-ID: <CANFp7mU1BOg1huNRQS8fAnXd1aGo9aZGDb-D+Mq6O9uVAaYXjQ@mail.gmail.com>
Date:   Fri, 5 Jun 2020 13:45:48 -0700
From:   Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Bluez mailing list <linux-bluetooth@...r.kernel.org>,
        Rocky Liao <rjliao@...eaurora.org>,
        Zijun Hu <zijuhu@...eaurora.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Balakrishna Godavarthi <bgodavar@...eaurora.org>,
        Claire Chang <tientzu@...omium.org>
Subject: Re: [PATCH 2/3] Bluetooth: hci_qca: Skip serdev wait when no transfer
 is pending

Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>

On Fri, Jun 5, 2020 at 11:46 AM Matthias Kaehlcke <mka@...omium.org> wrote:
>
> qca_suspend() calls serdev_device_wait_until_sent() regardless of
> whether a transfer is pending. While it does no active harm since
> the function should return immediately it makes the code more
> confusing. Add a flag to track whether a transfer is pending and
> only call serdev_device_wait_until_sent() is needed.
>
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>
>  drivers/bluetooth/hci_qca.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index b1d82d32892e9..90ffd8ca1fb0d 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -2050,6 +2050,7 @@ static int __maybe_unused qca_suspend(struct device *dev)
>         struct hci_uart *hu = &qcadev->serdev_hu;
>         struct qca_data *qca = hu->priv;
>         unsigned long flags;
> +       bool tx_pending = false;
>         int ret = 0;
>         u8 cmd;
>
> @@ -2083,6 +2084,7 @@ static int __maybe_unused qca_suspend(struct device *dev)
>
>                 qca->tx_ibs_state = HCI_IBS_TX_ASLEEP;
>                 qca->ibs_sent_slps++;
> +               tx_pending = true;
>                 break;
>
>         case HCI_IBS_TX_ASLEEP:
> @@ -2099,8 +2101,10 @@ static int __maybe_unused qca_suspend(struct device *dev)
>         if (ret < 0)
>                 goto error;
>
> -       serdev_device_wait_until_sent(hu->serdev,
> -                                     msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS));
> +       if (tx_pending) {
> +               serdev_device_wait_until_sent(hu->serdev,
> +                                             msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS));
> +       }
>
>         /* Wait for HCI_IBS_SLEEP_IND sent by device to indicate its Tx is going
>          * to sleep, so that the packet does not wake the system later.
> --
> 2.27.0.278.ge193c7cf3a9-goog
>