linux-kernel - Re: [PATCH 1/3] Bluetooth: hci_qca: Only remove TX clock vote after TX is completed

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Message-ID: <534a51662c623a512780e20162138469@codeaurora.org>
Date:   Sat, 06 Jun 2020 18:23:13 +0530
From:   bgodavar@...eaurora.org
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        linux-bluetooth@...r.kernel.org,
        Rocky Liao <rjliao@...eaurora.org>,
        Zijun Hu <zijuhu@...eaurora.org>, linux-kernel@...r.kernel.org,
        Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        Claire Chang <tientzu@...omium.org>
Subject: Re: [PATCH 1/3] Bluetooth: hci_qca: Only remove TX clock vote after
 TX is completed

Hi Matthias,

On 2020-06-06 00:16, Matthias Kaehlcke wrote:
> qca_suspend() removes the vote for the UART TX clock after
> writing an IBS sleep request to the serial buffer. This is
> not a good idea since there is no guarantee that the request
> has been sent at this point. Instead remove the vote after
> successfully entering IBS sleep. This also fixes the issue
> of the vote being removed in case of an aborted suspend due
> to a failure of entering IBS sleep.
> 
> Fixes: 41d5b25fed0a0 ("Bluetooth: hci_qca: add PM support")
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
> 
>  drivers/bluetooth/hci_qca.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index ece9f91cc3deb..b1d82d32892e9 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -2083,8 +2083,6 @@ static int __maybe_unused qca_suspend(struct 
> device *dev)
> 
>  		qca->tx_ibs_state = HCI_IBS_TX_ASLEEP;
>  		qca->ibs_sent_slps++;
> -
> -		qca_wq_serial_tx_clock_vote_off(&qca->ws_tx_vote_off);
>  		break;
> 
>  	case HCI_IBS_TX_ASLEEP:
> @@ -2112,8 +2110,10 @@ static int __maybe_unused qca_suspend(struct 
> device *dev)
>  			qca->rx_ibs_state == HCI_IBS_RX_ASLEEP,
>  			msecs_to_jiffies(IBS_BTSOC_TX_IDLE_TIMEOUT_MS));
> 
> -	if (ret > 0)
> +	if (ret > 0) {
> +		qca_wq_serial_tx_clock_vote_off(&qca->ws_tx_vote_off);
[Bala]: qca_wq_serial_tx_clock_vote_off votes for Tx clock off, when 
both Tx clock and Rx clock voted to off.
then only actual call to clock off is called.
https://elixir.bootlin.com/linux/latest/source/drivers/bluetooth/hci_qca.c#L312
I would recommend to vote Tx clock off after sending SLEEP BYTE from 
HOST TO BT SOC.

>  		return 0;
> +	}
> 
>  	if (ret == 0)
>  		ret = -ETIMEDOUT;