| Message ID | 20181220144639.15928-2-bgodavar@codeaurora.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | Bug fixes for Qualcomm BT chip wcn3990 | expand |
On Thu, Dec 20, 2018 at 08:16:35PM +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> > --- > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- > 1 file changed, 14 insertions(+), 24 deletions(-) > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c > index f036c8f98ea3..5a07c2370289 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; > + } > > - skb_put_u8(skb, cmd); > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; > - > - skb_queue_tail(&qca->txq, skb); > - hci_uart_tx_wakeup(hu); > + serdev_device_wait_until_sent(hu->serdev, 0); serdev_device_wait_until_sent() might only guarantee that the UART circular buffer is empty (see https://elixir.bootlin.com/linux/v4.19/source/drivers/tty/tty_ioctl.c#L225), not that the data has actually sent (e.g. it might be sitting in the UART FIFO). However with this: > /* Wait for 100 uS for SoC to settle down */ > usleep_range(100, 200); we should probably be fine, unless there's tons of data in the FIFO. You currently call serdev_device_write_flush() in qca_power_shutdown(), I wonder if it would make sense to call it in qca_send_power_pulse(), regardless of whether it's an on or off pulse. In any case we don't care if the chip receives any 'pending' data when we switch it on or off, right? Cheers Matthias
Hi Matthias, On 2018-12-22 07:29, Matthias Kaehlcke wrote: > On Thu, Dec 20, 2018 at 08:16:35PM +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> >> --- >> drivers/bluetooth/hci_qca.c | 38 >> ++++++++++++++----------------------- >> 1 file changed, 14 insertions(+), 24 deletions(-) >> >> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> index f036c8f98ea3..5a07c2370289 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; >> + } >> >> - skb_put_u8(skb, cmd); >> - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; >> - >> - skb_queue_tail(&qca->txq, skb); >> - hci_uart_tx_wakeup(hu); >> + serdev_device_wait_until_sent(hu->serdev, 0); > > serdev_device_wait_until_sent() might only guarantee that the UART > circular buffer is empty (see > https://elixir.bootlin.com/linux/v4.19/source/drivers/tty/tty_ioctl.c#L225), > not that the data has actually sent (e.g. it might be sitting in > the UART FIFO). However with this: > >> /* Wait for 100 uS for SoC to settle down */ >> usleep_range(100, 200); > > we should probably be fine, unless there's tons of data in the > FIFO. > > You currently call serdev_device_write_flush() in > qca_power_shutdown(), I wonder if it would make sense to call it in > qca_send_power_pulse(), regardless of whether it's an on or off [Bala]: during sending the ON pulse we will not have any data in the UART circular buffer as this is the first command to send and we are sending it as soon as we open the port. so i taught why should be flush the circular as it is already empty. > pulse. In any case we don't care if the chip receives any 'pending' > data when we switch it on or off, right? > [Bala]: during on we freshly open port and i see that flush() called while port opening. https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/serial_core.c#L207 > Cheers > > Matthias
On Wed, Dec 26, 2018 at 12:01:51PM +0530, Balakrishna Godavarthi wrote: > Hi Matthias, > > On 2018-12-22 07:29, Matthias Kaehlcke wrote: > > On Thu, Dec 20, 2018 at 08:16:35PM +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> > > > --- > > > drivers/bluetooth/hci_qca.c | 38 > > > ++++++++++++++----------------------- > > > 1 file changed, 14 insertions(+), 24 deletions(-) > > > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c > > > index f036c8f98ea3..5a07c2370289 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; > > > + } > > > > > > - skb_put_u8(skb, cmd); > > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; > > > - > > > - skb_queue_tail(&qca->txq, skb); > > > - hci_uart_tx_wakeup(hu); > > > + serdev_device_wait_until_sent(hu->serdev, 0); > > > > serdev_device_wait_until_sent() might only guarantee that the UART > > circular buffer is empty (see > > https://elixir.bootlin.com/linux/v4.19/source/drivers/tty/tty_ioctl.c#L225), > > not that the data has actually sent (e.g. it might be sitting in > > the UART FIFO). However with this: > > > > > /* Wait for 100 uS for SoC to settle down */ > > > usleep_range(100, 200); > > > > we should probably be fine, unless there's tons of data in the > > FIFO. > > > > You currently call serdev_device_write_flush() in > > qca_power_shutdown(), I wonder if it would make sense to call it in > > qca_send_power_pulse(), regardless of whether it's an on or off > > [Bala]: during sending the ON pulse we will not have any data in the > UART circular buffer as this is the first command to send and we are > sending it as soon as we open the port. > so i taught why should be flush the circular as it is already empty. > > pulse. In any case we don't care if the chip receives any 'pending' > > data when we switch it on or off, right? > > > > [Bala]: during on we freshly open port and i see that flush() called while > port opening. > > https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/serial_core.c#L207 I would argue that the serdev_device_write_flush() call in qca_power_shutdown() is related with/needed for sending the power off pulse, hence it should be part of qca_send_power_pulse(), unless it adds a significant overhead and we really want to call it only in the shutdown case. Flushing the buffer should be fairly lightweight and power pulses are only sent when the device is switched on or off, so the overhead should be negligible. You *could* restrict the flush to the power off pulse, assuming that the driver always re-opens the port in qca_wcn3990_init() (tests with this patch set suggest this might not be needed) and that serdev_device_open() flushes the buffer (which seems a sane assumption). Yet given the minimal overhead I'd suggest to not make assumptions about what happened previously in other code and avoid the clutter of a condition that doesn't add much value. Cheers Matthias
Hi Matthias, On 2018-12-27 03:51, Matthias Kaehlcke wrote: > On Wed, Dec 26, 2018 at 12:01:51PM +0530, Balakrishna Godavarthi wrote: >> Hi Matthias, >> >> On 2018-12-22 07:29, Matthias Kaehlcke wrote: >> > On Thu, Dec 20, 2018 at 08:16:35PM +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> >> > > --- >> > > drivers/bluetooth/hci_qca.c | 38 >> > > ++++++++++++++----------------------- >> > > 1 file changed, 14 insertions(+), 24 deletions(-) >> > > >> > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> > > index f036c8f98ea3..5a07c2370289 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; >> > > + } >> > > >> > > - skb_put_u8(skb, cmd); >> > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; >> > > - >> > > - skb_queue_tail(&qca->txq, skb); >> > > - hci_uart_tx_wakeup(hu); >> > > + serdev_device_wait_until_sent(hu->serdev, 0); >> > >> > serdev_device_wait_until_sent() might only guarantee that the UART >> > circular buffer is empty (see >> > https://elixir.bootlin.com/linux/v4.19/source/drivers/tty/tty_ioctl.c#L225), >> > not that the data has actually sent (e.g. it might be sitting in >> > the UART FIFO). However with this: >> > >> > > /* Wait for 100 uS for SoC to settle down */ >> > > usleep_range(100, 200); >> > >> > we should probably be fine, unless there's tons of data in the >> > FIFO. >> > >> > You currently call serdev_device_write_flush() in >> > qca_power_shutdown(), I wonder if it would make sense to call it in >> > qca_send_power_pulse(), regardless of whether it's an on or off >> >> [Bala]: during sending the ON pulse we will not have any data in the >> UART circular buffer as this is the first command to send and >> we are >> sending it as soon as we open the port. >> so i taught why should be flush the circular as it is already >> empty. > >> > pulse. In any case we don't care if the chip receives any 'pending' >> > data when we switch it on or off, right? >> > >> >> [Bala]: during on we freshly open port and i see that flush() called >> while >> port opening. >> >> https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/serial_core.c#L207 > > I would argue that the serdev_device_write_flush() call in > qca_power_shutdown() is related with/needed for sending the power off > pulse, hence it should be part of qca_send_power_pulse(), unless it > adds a significant overhead and we really want to call it only in the > shutdown case. > > Flushing the buffer should be fairly lightweight and power pulses are > only sent when the device is switched on or off, so the overhead > should be negligible. You *could* restrict the flush to the power off > pulse, assuming that the driver always re-opens the port in > qca_wcn3990_init() (tests with this patch set suggest this might not > be needed) and that serdev_device_open() flushes the buffer (which > seems a sane assumption). Yet given the minimal overhead I'd suggest > to not make assumptions about what happened previously in other code > and avoid the clutter of a condition that doesn't add much value. > [Bala]: will call the flush() while sending the power pulses irrespective of the pulse type. > Cheers > > Matthias
On Fri, Dec 21, 2018 at 05:59:47PM -0800, Matthias Kaehlcke wrote: > On Thu, Dec 20, 2018 at 08:16:35PM +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> > > --- > > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- > > 1 file changed, 14 insertions(+), 24 deletions(-) > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c > > index f036c8f98ea3..5a07c2370289 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; > > + } > > > > - skb_put_u8(skb, cmd); > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; > > - > > - skb_queue_tail(&qca->txq, skb); > > - hci_uart_tx_wakeup(hu); > > + serdev_device_wait_until_sent(hu->serdev, 0); Again, do you really want to wait indefinitely here? > serdev_device_wait_until_sent() might only guarantee that the UART > circular buffer is empty (see > https://elixir.bootlin.com/linux/v4.19/source/drivers/tty/tty_ioctl.c#L225), > not that the data has actually sent (e.g. it might be sitting in > the UART FIFO). For serial core, uart_wait_until_sent() makes sure also the UART FIFO is empty, although it may time out when using flow control (as then the FIFO may never empty, and flow control appears to be enabled here). Johan
Hi Johan, On 2019-01-09 20:08, Johan Hovold wrote: > On Fri, Dec 21, 2018 at 05:59:47PM -0800, Matthias Kaehlcke wrote: >> On Thu, Dec 20, 2018 at 08:16:35PM +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> >> > --- >> > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- >> > 1 file changed, 14 insertions(+), 24 deletions(-) >> > >> > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> > index f036c8f98ea3..5a07c2370289 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; >> > + } >> > >> > - skb_put_u8(skb, cmd); >> > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; >> > - >> > - skb_queue_tail(&qca->txq, skb); >> > - hci_uart_tx_wakeup(hu); >> > + serdev_device_wait_until_sent(hu->serdev, 0); > > Again, do you really want to wait indefinitely here? > [Bala]: these commands are mandatory to turn ON or OFF the chip. so blocking to the max time is required. these commands are sent during the BT chip ON & OFF. in the latest series, i have flushed the uart before sending this commands so the uart FIFO(as just opened the port before calling this function) or the circular buffer will be empty and also i am disabling the flow control too. https://patchwork.kernel.org/patch/10744435/ >> serdev_device_wait_until_sent() might only guarantee that the UART >> circular buffer is empty (see >> https://elixir.bootlin.com/linux/v4.19/source/drivers/tty/tty_ioctl.c#L225), >> not that the data has actually sent (e.g. it might be sitting in >> the UART FIFO). > > For serial core, uart_wait_until_sent() makes sure also the UART FIFO > is > empty, although it may time out when using flow control (as then the > FIFO may never empty, and flow control appears to be enabled here). > > Johan [Bala]: Pls refer the latest patch series https://patchwork.kernel.org/patch/10744435/ where i am flushing the circular buffer before calling the qca_send_power_pulse(). this how the flow 1. open serial port (gurantess that UART FIFO is empty) 2. flush the circular buffer 3. disable the flow control. 4. send the command byte. 5. wait for the circular buffer is empty. the above is one time process,
On Thu, Jan 10, 2019 at 08:18:37PM +0530, Balakrishna Godavarthi wrote: > Hi Johan, > > On 2019-01-09 20:08, Johan Hovold wrote: > > On Fri, Dec 21, 2018 at 05:59:47PM -0800, Matthias Kaehlcke wrote: > > > On Thu, Dec 20, 2018 at 08:16:35PM +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> > > > > --- > > > > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- > > > > 1 file changed, 14 insertions(+), 24 deletions(-) > > > > > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c > > > > index f036c8f98ea3..5a07c2370289 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; > > > > + } > > > > > > > > - skb_put_u8(skb, cmd); > > > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; > > > > - > > > > - skb_queue_tail(&qca->txq, skb); > > > > - hci_uart_tx_wakeup(hu); > > > > + serdev_device_wait_until_sent(hu->serdev, 0); > > > > Again, do you really want to wait indefinitely here? > > > [Bala]: these commands are mandatory to turn ON or OFF the chip. > so blocking to the max time is required. > these commands are sent during the BT chip ON & OFF. > in the latest series, i have flushed the uart before sending this > commands > so the uart FIFO(as just opened the port before calling this > function) or the circular > buffer will be empty and also i am disabling the flow control too. > https://patchwork.kernel.org/patch/10744435/ The commands may be mandatory for switching the chip on or off, but what is better if there is a problem with sending them (e.g. a buggy UART driver): 1. wait a reasonable time, report an error 2. wait forever ? If the single byte command couldn't be sent after a few milliseconds, it likely never will, waiting forever doesn't fix that. An error report at least provides some information about the problem and the driver is in a not-hanging state. Cheers Matthias
On 2019-01-11 06:25, Matthias Kaehlcke wrote: > On Thu, Jan 10, 2019 at 08:18:37PM +0530, Balakrishna Godavarthi wrote: >> Hi Johan, >> >> On 2019-01-09 20:08, Johan Hovold wrote: >> > On Fri, Dec 21, 2018 at 05:59:47PM -0800, Matthias Kaehlcke wrote: >> > > On Thu, Dec 20, 2018 at 08:16:35PM +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> >> > > > --- >> > > > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- >> > > > 1 file changed, 14 insertions(+), 24 deletions(-) >> > > > >> > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> > > > index f036c8f98ea3..5a07c2370289 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; >> > > > + } >> > > > >> > > > - skb_put_u8(skb, cmd); >> > > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; >> > > > - >> > > > - skb_queue_tail(&qca->txq, skb); >> > > > - hci_uart_tx_wakeup(hu); >> > > > + serdev_device_wait_until_sent(hu->serdev, 0); >> > >> > Again, do you really want to wait indefinitely here? >> > >> [Bala]: these commands are mandatory to turn ON or OFF the chip. >> so blocking to the max time is required. >> these commands are sent during the BT chip ON & OFF. >> in the latest series, i have flushed the uart before sending >> this >> commands >> so the uart FIFO(as just opened the port before calling this >> function) or the circular >> buffer will be empty and also i am disabling the flow control >> too. >> https://patchwork.kernel.org/patch/10744435/ > > The commands may be mandatory for switching the chip on or off, but > what is better if there is a problem with sending them (e.g. a buggy > UART driver): > > 1. wait a reasonable time, report an error > 2. wait forever > > ? > > If the single byte command couldn't be sent after a few milliseconds, > it likely never will, waiting forever doesn't fix that. An error > report at least provides some information about the problem and the > driver is in a not-hanging state. > > Cheers > > Matthias [Bala]: will update this with a bound TIMEOUT value. But wait_until_sent() is void return type how could we know that the data is sent out on the lines.
On Fri, Jan 11, 2019 at 08:02:00PM +0530, Balakrishna Godavarthi wrote: > On 2019-01-11 06:25, Matthias Kaehlcke wrote: > > On Thu, Jan 10, 2019 at 08:18:37PM +0530, Balakrishna Godavarthi wrote: > > > Hi Johan, > > > > > > On 2019-01-09 20:08, Johan Hovold wrote: > > > > On Fri, Dec 21, 2018 at 05:59:47PM -0800, Matthias Kaehlcke wrote: > > > > > On Thu, Dec 20, 2018 at 08:16:35PM +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> > > > > > > --- > > > > > > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- > > > > > > 1 file changed, 14 insertions(+), 24 deletions(-) > > > > > > > > > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c > > > > > > index f036c8f98ea3..5a07c2370289 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; > > > > > > + } > > > > > > > > > > > > - skb_put_u8(skb, cmd); > > > > > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; > > > > > > - > > > > > > - skb_queue_tail(&qca->txq, skb); > > > > > > - hci_uart_tx_wakeup(hu); > > > > > > + serdev_device_wait_until_sent(hu->serdev, 0); > > > > > > > > Again, do you really want to wait indefinitely here? > > > > > > > [Bala]: these commands are mandatory to turn ON or OFF the chip. > > > so blocking to the max time is required. > > > these commands are sent during the BT chip ON & OFF. > > > in the latest series, i have flushed the uart before sending > > > this > > > commands > > > so the uart FIFO(as just opened the port before calling this > > > function) or the circular > > > buffer will be empty and also i am disabling the flow > > > control too. > > > https://patchwork.kernel.org/patch/10744435/ > > > > The commands may be mandatory for switching the chip on or off, but > > what is better if there is a problem with sending them (e.g. a buggy > > UART driver): > > > > 1. wait a reasonable time, report an error > > 2. wait forever > > > > ? > > > > If the single byte command couldn't be sent after a few milliseconds, > > it likely never will, waiting forever doesn't fix that. An error > > report at least provides some information about the problem and the > > driver is in a not-hanging state. > > > > Cheers > > > > Matthias > > [Bala]: will update this with a bound TIMEOUT value. But wait_until_sent() > is void return > type how could we know that the data is sent out on the lines. Good point, I didn't check and expected it to return an error. If you feel really motivated and have maintainer support you could possibly change the API, however it seems this would be a somewhat larger change. I guess the next best thing to do is to proceed as if all data was sent and if there was a problem it will likely manifest through another error (especially for the ON pulse), which still seems better than a hanging driver. Cheers Matthias
Hi Matthias, On 2019-01-12 05:08, Matthias Kaehlcke wrote: > On Fri, Jan 11, 2019 at 08:02:00PM +0530, Balakrishna Godavarthi wrote: >> On 2019-01-11 06:25, Matthias Kaehlcke wrote: >> > On Thu, Jan 10, 2019 at 08:18:37PM +0530, Balakrishna Godavarthi wrote: >> > > Hi Johan, >> > > >> > > On 2019-01-09 20:08, Johan Hovold wrote: >> > > > On Fri, Dec 21, 2018 at 05:59:47PM -0800, Matthias Kaehlcke wrote: >> > > > > On Thu, Dec 20, 2018 at 08:16:35PM +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> >> > > > > > --- >> > > > > > drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- >> > > > > > 1 file changed, 14 insertions(+), 24 deletions(-) >> > > > > > >> > > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> > > > > > index f036c8f98ea3..5a07c2370289 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; >> > > > > > + } >> > > > > > >> > > > > > - skb_put_u8(skb, cmd); >> > > > > > - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; >> > > > > > - >> > > > > > - skb_queue_tail(&qca->txq, skb); >> > > > > > - hci_uart_tx_wakeup(hu); >> > > > > > + serdev_device_wait_until_sent(hu->serdev, 0); >> > > > >> > > > Again, do you really want to wait indefinitely here? >> > > > >> > > [Bala]: these commands are mandatory to turn ON or OFF the chip. >> > > so blocking to the max time is required. >> > > these commands are sent during the BT chip ON & OFF. >> > > in the latest series, i have flushed the uart before sending >> > > this >> > > commands >> > > so the uart FIFO(as just opened the port before calling this >> > > function) or the circular >> > > buffer will be empty and also i am disabling the flow >> > > control too. >> > > https://patchwork.kernel.org/patch/10744435/ >> > >> > The commands may be mandatory for switching the chip on or off, but >> > what is better if there is a problem with sending them (e.g. a buggy >> > UART driver): >> > >> > 1. wait a reasonable time, report an error >> > 2. wait forever >> > >> > ? >> > >> > If the single byte command couldn't be sent after a few milliseconds, >> > it likely never will, waiting forever doesn't fix that. An error >> > report at least provides some information about the problem and the >> > driver is in a not-hanging state. >> > >> > Cheers >> > >> > Matthias >> >> [Bala]: will update this with a bound TIMEOUT value. But >> wait_until_sent() >> is void return >> type how could we know that the data is sent out on the lines. > > Good point, I didn't check and expected it to return an error. If you > feel really motivated and have maintainer support you could possibly > change the API, however it seems this would be a somewhat larger > change. > > I guess the next best thing to do is to proceed as if all data was > sent and if there was a problem it will likely manifest through > another error (especially for the ON pulse), which still seems better > than a hanging driver. > > Cheers > > Matthias [Bala]: sure, will add the timeout to one second and if data didn't sent to the lines anyways we will get an version command timeouts errors.
diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c index f036c8f98ea3..5a07c2370289 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; + } - skb_put_u8(skb, cmd); - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; - - skb_queue_tail(&qca->txq, skb); - hci_uart_tx_wakeup(hu); + serdev_device_wait_until_sent(hu->serdev, 0); /* Wait for 100 uS for SoC to settle down */ usleep_range(100, 200); @@ -1116,7 +1111,6 @@ static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type) static int qca_wcn3990_init(struct hci_uart *hu) { - struct hci_dev *hdev = hu->hdev; struct qca_serdev *qcadev; int ret; @@ -1139,12 +1133,12 @@ static int qca_wcn3990_init(struct hci_uart *hu) /* Forcefully enable wcn3990 to enter in to boot mode. */ host_set_baudrate(hu, 2400); - ret = qca_send_power_pulse(hdev, QCA_WCN3990_POWEROFF_PULSE); + ret = qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE); if (ret) return ret; qca_set_speed(hu, QCA_INIT_SPEED); - ret = qca_send_power_pulse(hdev, QCA_WCN3990_POWERON_PULSE); + ret = qca_send_power_pulse(hu, QCA_WCN3990_POWERON_PULSE); if (ret) return ret; @@ -1274,13 +1268,9 @@ static const struct qca_vreg_data qca_soc_data = { static void qca_power_shutdown(struct hci_uart *hu) { - struct serdev_device *serdev = hu->serdev; - unsigned char cmd = QCA_WCN3990_POWEROFF_PULSE; - + serdev_device_write_flush(hu->serdev); host_set_baudrate(hu, 2400); - hci_uart_set_flow_control(hu, true); - serdev_device_write_buf(serdev, &cmd, sizeof(cmd)); - hci_uart_set_flow_control(hu, false); + qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE); qca_power_setup(hu, false); }
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> --- drivers/bluetooth/hci_qca.c | 38 ++++++++++++++----------------------- 1 file changed, 14 insertions(+), 24 deletions(-)