Messages in this thread | | | Date | Tue, 11 Dec 2018 21:12:34 +0530 | From | Balakrishna Godavarthi <> | Subject | Re: [PATCH v3 1/4] Bluetooth: hci_qca: use wait_until_sent() for power pulses |
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Hi Johan,
On 2018-12-06 16:10, Balakrishna Godavarthi wrote: > Hi Johan, > > On 2018-12-05 11:55, Johan Hovold wrote: >> On Fri, Nov 30, 2018 at 08:32:44PM +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> >>> --- >>> v3: >>> * no change. >>> v2: >>> * Updated function qca_send_power_pulse() >>> * addressed reviewer comments. >> >> Please make sure to include reviewers on CC when resending, and as >> someone else already mentioned, be a bit more specific about what >> changes you actually made in response to the review feedback you >> received. >> > > [Bala]: sure will add and provide more info in version change history. > >>> 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..f5dd323c1967 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(hu->serdev, &cmd, sizeof(cmd), 0); >> >> You're still using 0 as a timeout here which is broken, as I already >> told you. >> > > [Bala]: got the change now will update to timeout to non zero value. > >> From 4.21 this will result in an indefinite timeout, but currently >> implies not to wait for a full write buffer to drain at all. >> >> As I also mentioned, you need to to make sure to call >> serdev_device_write_wakeup() in the write_wakup() path if you are >> going >> to use serdev_device_write() at all. >> > > [Bala]: this where i am confused. > calling serdev_device_write is calling an wakeup internally. > below is the flow > > ttyport_write_buf: > * calling serdev_device_write() will call write_buf() in > this call we are enabling bit "TTY_DO_WRITE_WAKEUP" and calling > write() > i.e. uart_write() where we call in start_tx. this will > go to the vendor specific write where in isr we call > uart_write_wakeup() > > https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/qcom_geni_serial.c#L756 > > > uart_write_wakeup()->ttyport_write_wakeup()->serdev_controller_write_wakeup()->hci_uart_write_wakeup()->hci_uart_tx_wakeup() > > the above is flow when serdev_device_write() is called, it is > indirectly calling serdev_write_wakeup(). > > Why actual we need to call an serdev_write_wakeup() is this > wakeup related to the UART port or for the BT chip. > >> Johan
Can you help me to understand, whether my understating is correct wrt serdev_wakeup().
-- Regards Balakrishna.
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