From: "K, Kiran" <kiran.k@intel.com>
To: Oliver Neukum <oneukum@suse.com>, Marcel Holtmann <marcel@holtmann.org>
Cc: "linux-bluetooth@vger.kernel.org"
<linux-bluetooth@vger.kernel.org>,
"Srivatsa, Ravishankar" <ravishankar.srivatsa@intel.com>,
"Devegowda, Chandrashekar" <chandrashekar.devegowda@intel.com>,
"Tumkur Narayan, Chethan" <chethan.tumkur.narayan@intel.com>
Subject: RE: question regarding ordering in btintel_pcie_send_sync()
Date: Thu, 16 May 2024 13:28:58 +0000 [thread overview]
Message-ID: <PH0PR11MB7585901BCD41AC665844FF73F5ED2@PH0PR11MB7585.namprd11.prod.outlook.com> (raw)
In-Reply-To: <2ec916ce-c7b9-40f5-bb08-d1d2ba564456@suse.com>
Hi Oliver,
>-----Original Message-----
>From: Oliver Neukum <oneukum@suse.com>
>Sent: Thursday, May 16, 2024 11:28 AM
>To: K, Kiran <kiran.k@intel.com>; Marcel Holtmann <marcel@holtmann.org>
>Cc: linux-bluetooth@vger.kernel.org
>Subject: question regarding ordering in btintel_pcie_send_sync()
>
>Hi,
>
>I was looking at the code. I do not have documentation for the device, but it
>looks relatively ordinary. Hence this piece of code caught my eye:
>
>
> /* Set the doorbell to notify the device */
> btintel_pcie_set_tx_db(data, tfd_index);
>
>Requesting an interrupt. However, are you sure the IO can be processed and
>trigger an interrupt only after the PCI write, which this triggers?
>
This wait is for reception of packet at the device side. Bluetooth controller can raise the interrupt with different causes. Here driver waits for interrupt BTINTEL_*_CAUSE_0 which indicates that TX has been completed. Device raises BTINTEL_*_CAUSE_1 interrupt when TX packet has been processed and there is some data in RX queue to be read by driver.
> /* Wait for the complete interrupt - URBD0 */
> ret = wait_event_timeout(data->tx_wait_q, data->tx_wait_done,
> msecs_to_jiffies(BTINTEL_PCIE_TX_WAIT_TIMEOUT_MS));
>
> Regards
> Oliver
Thanks,
Kiran
prev parent reply other threads:[~2024-05-16 13:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-16 5:57 question regarding ordering in btintel_pcie_send_sync() Oliver Neukum
2024-05-16 13:28 ` K, Kiran [this message]
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