Re: [PATCH v7 4/4] Bluetooth: btqca: inject command complete event during fw download

From: Balakrishna Godavarthi
Date: Wed Jan 16 2019 - 04:36:35 EST

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On 2019-01-15 06:50, Matthias Kaehlcke wrote:

On Mon, Jan 14, 2019 at 09:21:25PM +0530, Balakrishna Godavarthi wrote:

On 2019-01-12 04:42, Matthias Kaehlcke wrote:
> On Fri, Jan 11, 2019 at 07:53:43PM +0530, Balakrishna Godavarthi wrote:
> > Hi Matthias,
> >
> > On 2019-01-11 02:13, Matthias Kaehlcke wrote:
> > > Hi Balakrishna,
> > >
> > > On Thu, Jan 10, 2019 at 08:30:43PM +0530, Balakrishna Godavarthi wrote:
> > > > Hi Matthias,
> > > >
> > > > On 2019-01-03 03:45, Matthias Kaehlcke wrote:
> > > > > On Mon, Dec 31, 2018 at 11:34:46AM +0530, Balakrishna Godavarthi wrote:
> > > > > > Hi Marcel,
> > > > > >
> > > > > > On 2018-12-30 13:40, Marcel Holtmann wrote:
> > > > > > > Hi Balakrishna,
> > > > > > >
> > > > > > > > > > Latest qualcomm chips are not sending an command complete event for
> > > > > > > > > > every firmware packet sent to chip. They only respond with a vendor
> > > > > > > > > > specific event for the last firmware packet. This optimization will
> > > > > > > > > > decrease the BT ON time. Due to this we are seeing a timeout error
> > > > > > > > > > message logs on the console during firmware download. Now we are
> > > > > > > > > > injecting a command complete event once we receive an vendor
> > > > > > > > > > specific
> > > > > > > > > > event for the last RAM firmware packet.
> > > > > > > > > > Signed-off-by: Balakrishna Godavarthi <bgodavar@xxxxxxxxxxxxxx>
> > > > > > > > > > ---
> > > > > > > > > > drivers/bluetooth/btqca.c | 39
> > > > > > > > > > ++++++++++++++++++++++++++++++++++++++-
> > > > > > > > > > drivers/bluetooth/btqca.h | 3 +++
> > > > > > > > > > 2 files changed, 41 insertions(+), 1 deletion(-)
> > > > > > > > > > diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
> > > > > > > > > > index ec9e03a6b778..0b533f65f652 100644
> > > > > > > > > > --- a/drivers/bluetooth/btqca.c
> > > > > > > > > > +++ b/drivers/bluetooth/btqca.c
> > > > > > > > > > @@ -144,6 +144,7 @@ static void qca_tlv_check_data(struct
> > > > > > > > > > rome_config *config,
> > > > > > > > > > * In case VSE is skipped, only the last segment is acked.
> > > > > > > > > > */
> > > > > > > > > > config->dnld_mode = tlv_patch->download_mode;
> > > > > > > > > > + config->dnld_type = config->dnld_mode;
> > > > > > > > > > BT_DBG("Total Length : %d bytes",
> > > > > > > > > > le32_to_cpu(tlv_patch->total_size));
> > > > > > > > > > @@ -264,6 +265,31 @@ static int qca_tlv_send_segment(struct
> > > > > > > > > > hci_dev *hdev, int seg_size,
> > > > > > > > > > return err;
> > > > > > > > > > }
> > > > > > > > > > +static int qca_inject_cmd_complete_event(struct hci_dev *hdev)
> > > > > > > > > > +{
> > > > > > > > > > + struct hci_event_hdr *hdr;
> > > > > > > > > > + struct hci_ev_cmd_complete *evt;
> > > > > > > > > > + struct sk_buff *skb;
> > > > > > > > > > +
> > > > > > > > > > + skb = bt_skb_alloc(sizeof(*hdr) + sizeof(*evt) + 1, GFP_KERNEL);
> > > > > > > > > > + if (!skb)
> > > > > > > > > > + return -ENOMEM;
> > > > > > > > > > +
> > > > > > > > > > + hdr = skb_put(skb, sizeof(*hdr));
> > > > > > > > > > + hdr->evt = HCI_EV_CMD_COMPLETE;
> > > > > > > > > > + hdr->plen = sizeof(*evt) + 1;
> > > > > > > > > > +
> > > > > > > > > > + evt = skb_put(skb, sizeof(*evt));
> > > > > > > > > > + evt->ncmd = 1;
> > > > > > > > > > + evt->opcode = HCI_OP_NOP;
> > > > >
> > > > > After looking a bit more at it I realize HCI_OP_NOP is not a good
> > > > > value in this case:
> > > > >
> > > > > static void hci_cmd_complete_evt(...)
> > > > > {
> > > > > ...
> > > > >
> > > > > if (*opcode != HCI_OP_NOP)
> > > > > cancel_delayed_work(&hdev->cmd_timer);
> > > > >
> > > > > ...
> > > > > }
> > > > >
> > > > > https://elixir.bootlin.com/linux/v4.19/source/net/bluetooth/hci_event.c#L3351
> > > > >
> > > > > Cancelling the command timeout is precisely what we want. Not sure why
> > > > > the patch with HCI_OP_NOP makes the timeouts go away in most cases
> > > > > (but not e.g. when inserting an msleep(1000) after downloading the
> > > > > NVM.
> > > > >
> > > > > I suggest to pass the opcode of the command to be completed.
> > > > >
> > > > > > > > > > +
> > > > > > > > > > + skb_put_u8(skb, QCA_HCI_CC_SUCCESS);
> > > > > > > > > > +
> > > > > > > > > > + hci_skb_pkt_type(skb) = HCI_EVENT_PKT;
> > > > > > > > > > +
> > > > > > > > > > + return hci_recv_frame(hdev, skb);
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > static int qca_download_firmware(struct hci_dev *hdev,
> > > > > > > > > > struct rome_config *config)
> > > > > > > > > > {
> > > > > > > > > > @@ -297,11 +323,22 @@ static int
> > > > > > > > > > qca_download_firmware(struct hci_dev *hdev,
> > > > > > > > > > ret = qca_tlv_send_segment(hdev, segsize, segment,
> > > > > > > > > > config->dnld_mode);
> > > > > > > > > > if (ret)
> > > > > > > > > > - break;
> > > > > > > > > > + goto out;
> > > > > > > > > > segment += segsize;
> > > > > > > > > > }
> > > > > > > > > > + /* Latest qualcomm chipsets are not sending a command
> > > > > > > > > > complete event
> > > > > > > > > > + * for every fw packet sent. They only respond with a
> > > > > > > > > > vendor specific
> > > > > > > > > > + * event for the last packet. This optimization in the chip will
> > > > > > > > > > + * decrease the BT in initialization time. Here we will
> > > > > > > > > > inject a command
> > > > > > > > > > + * complete event to avoid a command timeout error message.
> > > > > > > > > > + */
> > > > > > > > > > + if ((config->dnld_type == ROME_SKIP_EVT_VSE_CC ||
> > > > > > > > > > + config->dnld_type == ROME_SKIP_EVT_VSE))
> > > > > > > > > > + return qca_inject_cmd_complete_event(hdev);
> > > > > > > > > > +
> > > > > > > > > have you actually considered using __hci_cmd_send in that case. It is
> > > > > > > > > allowed for vendor OGF to use that command. I see you actually do use
> > > > > > > > > it and now I am failing to understand what this is for.
> > > > > > > > [Bala]: thanks for reviewing the change.
> > > > > > > >
> > > > > > > > __hci_cmd_send() can be used only to send the command to the chip.
> > > > > > > > it will not wait for the response for the command sent.
> > > > > > > >
> > > > > > > > as you know that every vendor command sent to chip will respond with
> > > > > > > > vendor specific event and command complete event.
> > > > > > > > but in our case chip will only respond with vendor specific event
> > > > > > > > only. so we are injecting command complete event.
> > > > > > >
> > > > > > > and __hci_cmd_sync_ev is also not working for you? However since you
> > > > > > > are not waiting for the vendor event anyway and just injecting
> > > > > > > cmd_complete, I wonder whatâs the difference in just using
> > > > > > > __hci_cmd_send and not bothering to wait or inject at all. I am
> > > > > > > failing to see where this injection makes a difference.
> > > > > > >
> > > > > > > For me it is a big difference if we are injecting one event like in
> > > > > > > the case of Intel compared to injecting one for every command. It will
> > > > > > > show a wrong picture in btmon and that is a bad idea.
> > > > > > >
> > > > > > > Regards
> > > > > > >
> > > > > > > Marcel
> > > > > >
> > > > > > [Bala]: here is the use case, when ever we download the fw packets
> > > > > > i.e. RAM
> > > > > > image, for every command sent(i.e. fw packet) from
> > > > > > the host chip will respond with an vendor specific event and command
> > > > > > complete event.
> > > > > >
> > > > > > the above is taking more time to setup the BT device. then we came
> > > > > > up with
> > > > > > solution where we enable flags in fw file (i.e. RAM image header)
> > > > > > whether to wait for event to be received or sent the total packets
> > > > > > and wait
> > > > > > for the events for the last packet.
> > > > > >
> > > > > > So currently we are handling both the cases in the code. i.e wait
> > > > > > for event
> > > > > > for all packet or wait for an event for the last packet.
> > > > > >
> > > > > > but in the second case i.e. wait for event for the last packet sent,
> > > > > > we are
> > > > > > only receiving an vendor specific event from chip which holds the
> > > > > > status of
> > > > > > fw download.
> > > > > >
> > > > > > so as __hci_cmd_sync_ev() requires an command complete event. so we
> > > > > > are
> > > > > > injecting it after the vendor specific event received for the last
> > > > > > packet.
> > > > > >
> > > > > > This helps to overcome 0xfc00 timeout error logging on console.
> > > > >
> > > > > Some more details:
> > > > >
> > > > > The timeout error is actually from reading the 'SoC version', which
> > > > > uses the same command code as the firmware download
> > > > > (EDL_PATCH_CMD_OPCODE). Without reading the 'SoC version' it would be
> > > > > from the command to write the first firmware segment.
> > > > >
> > > > > If the download of a firmware binary takes >= 2s (HCI_CMD_TIMEOUT) the
> > > > > timeout would still occur. If necessary this could be mitigated by
> > > > > injecting some command complete events during the firmware download,
> > > > > though I expect Marcel wouldn't be overly happy with that, since it
> > > > > would affect btmon even more.
> > > > >
> > > > > Regards
> > > > >
> > > > > Matthias
> > > >
> > > > [Bala]: Basically every vendor specific command we sent to chip,
> > > > chip should respond with an vendor specific event followed by an
> > > > command
> > > > complete event
> > > > or some times it will only respond with an command complete event.
> > > > but in any case command complete event is mandatory to all the
> > > > command we
> > > > sent to the chip.
> > >
> > > Is this ("command complete event is mandatory to all the command we
> > > sent to the chip") a description of what the chip actually does, or
> > > what it should be doing according to the spec?
> > >
> > > As mentioned earlier, the timeout we see originates from reading the
> > > SoC version:
> > >
> > > diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
> > > index 0b533f65f652fc..1e484e61799571 100644
> > > --- a/drivers/bluetooth/btqca.c
> > > +++ b/drivers/bluetooth/btqca.c
> > > @@ -400,6 +400,10 @@ int qca_uart_setup(struct hci_dev *hdev, uint8_t
> > > baudrate,
> > > return err;
> > > }
> > >
> > > + printk("DBG: ZZZzzzzzzz\n");
> > > + msleep(2500);
> > > + printk("DBG: good morning!\n");
> > > +
> > > /* Download NVM configuration */
> > > config.type = TLV_TYPE_NVM;
> > > if (soc_type == QCA_WCN3990)
> > >
> > > When you boot with this patch you'll see something like this:
> > >
> > > [ 15.531365] DBG: reading SoC version
> > > [ 15.544963] DBG: ZZZzzzzzzz
> > > [ 17.590282] Bluetooth: hci0: command 0xfc00 tx timeout
> > > [ 18.099110] DBG: good morning!
> > >
> >
> > [Bala]: my previous analysis were wrong. thanks for pointing me to the
> > correct issue.
> > i am able to see timeout after version command.(used some
> > sleep)
> > here is the reason for it.
> >
> > 01 00 fc 01 19 (we send the command to chip to request
> > version)
> > 04 ff 0e 00 02 0a 00 00 00 01 00 01 02 14 02 01 40(chip will
> > respond
> > with the vendor specific event payload will be chip version)
> > 04 0e 04 01 00 00 00(command complete event)
> >
> > issue is with command complete event. ideally command
> > complete event
> > payload holds the command for which chip sends command complete event.
> >
> > breaking the command
> >
> > 04 : event packet (fixed)
> > 0e : command complete event(fixed)
> > 04 : size of the payload,
> >
> > 01 : no of commands in the payload
> > 00 : OCF (opocde lsb)
> > 00 : OGF (opcode msb)
> > 00 : status of command executed,
> >
> > payload is form byte 4 to byte 7. which hold the command i.e
> > opcode
> > form the above response opcode is 0x0000. ideally this should be
> > 0xfc00
> > because the command complete response from the chip is for the
> > command
> > 0xfc00.
> >
> > Checked with Chip firmware dev team for the reason, it was an
> > limitation or an bug in the chip ROM firmware
> > in the current chipset, which is fixed in the coming chipset.
> >
> > so we expect the command 0xfc00 but recevuies 0x00. so that is
> > the
> > reason we see an timeouts.
> > for all the vendor commands we receive 0x0000 in the command
> > complete
> > event.
>
> Thanks for your analysis.
>
> It is unfortunate (though not unexpected) that this is a problem in
> the ROM were we can't fix it, but at least the FW team is aware of it
> and fixed it for future hardware.
>
> > if comes a new question how are we not seeing an 0xfc00 when
> > we inject
> > an command complete event.
> > i experimented this patch, when i inject the command complete
> > event
> > from the soc version still i can see the command timeouts.
>
> I don't see command timeouts when injecting a command complete event
> after reading the SoC version. I suspect you still use patch which
> injects a command complete event with HCI_OP_NOP, which is precisely
> what the chip does ...
>
[Bala]: i am seeing command timeout after injecting cc event after read
version request.

> > The reason for no timeouts error, we are injecting an command
> > complete
> > after last packet sent out, so this injection helps
> > .bin file to speed out it download part, so as the bin is dumped
> > fastly we send an HCI RESET Comamnd where we recevie an command
> > complete
> > event
> > with non zero opcode which is cancelling the command timeout
> > timer.
> >
> > when we inject command complete event, in short we are
> > completing
> > setup process in less than 2 seconds(command timeout timer value),
> > so before 2 seconds we are sending an HCI RESET command whose
> > command
> > complete event opcode value is an non zero (which cancels the command
> > timeout timer)
>
> I agree that HCI_RESET cancels the command timeout timer if it is sent
> before the 2s timout expires, but I have doubts on the part about
> command complete events.
>
> In my observations there are no command timeouts if a command complete
> (with opcode != HCI_OP_NOP) is injected after the firmware download,
> even if a 3s sleep is added before sending the HCI_RESET.
>

[Bala]: add sleep before sending HCI reset, oxfc00 timeout observed.

Please double check your setup. Are you 100% sure you are not still
sending HCI_OP_NOP as opcode?

[Bala]: sorry i am injecting the HCI_OP_NOP, so that is the reason we have an timeouts.
yes if the opcode 0x42 injected, no timeouts are observed.

This is the diff I use for debugging on top of your patchset:

diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
index 0b533f65f652fc..5bb9e0ca7c348b 100644
--- a/drivers/bluetooth/btqca.c
+++ b/drivers/bluetooth/btqca.c
@@ -27,6 +27,8 @@

#define VERSION "0.1"

+static int qca_inject_cmd_complete_event(struct hci_dev *hdev);
+
int qca_read_soc_version(struct hci_dev *hdev, u32 *soc_version)
{
struct sk_buff *skb;
@@ -84,6 +86,11 @@ int qca_read_soc_version(struct hci_dev *hdev, u32
*soc_version)
if (*soc_version == 0)
err = -EILSEQ;

+ qca_inject_cmd_complete_event(hdev);
+ printk("DBG: ZZZzzzzzzz\n");
+ msleep(2500);
+ printk("DBG: good morning!\n");
+
out:
kfree_skb(skb);
if (err)
@@ -281,7 +288,7 @@ static int qca_inject_cmd_complete_event(struct
hci_dev *hdev)

evt = skb_put(skb, sizeof(*evt));
evt->ncmd = 1;
- evt->opcode = HCI_OP_NOP;
+ evt->opcode = 0x42;

skb_put_u8(skb, QCA_HCI_CC_SUCCESS);

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index f12555f23a49a0..c87ac1823439ab 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3348,8 +3348,11 @@ static void hci_cmd_complete_evt(struct hci_dev
*hdev, struct sk_buff *skb,
break;
}

- if (*opcode != HCI_OP_NOP)
+ if (*opcode != HCI_OP_NOP) {
+ printk("DBG: cancelling command timer (opcode = 0x%02x)\n",
+ *opcode);
cancel_delayed_work(&hdev->cmd_timer);
+ }

if (ev->ncmd && !test_bit(HCI_RESET, &hdev->flags))
atomic_set(&hdev->cmd_cnt, 1);

With that I see:

[ 18.725417] Bluetooth: hci0: setting up wcn3990
[ 18.860381] DBG: ZZZzzzzzzz
[ 18.863332] DBG: cancelling command timer (opcode = 0x42)
[ 21.427085] DBG: good morning!

The timer is clearly cancelled by the injected command (opcode 0x42)
and no timeout occurs. I wouldn't expect you to see anything vastly
different.

Cheers

Matthias

[Bala]: I think it would be better if we inject a command complete event after we
receive the version data. instead of injecting in between firmware download.
this change will be only for wcn3990.

--
Regards
Balakrishna.

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Next in thread: Matthias Kaehlcke: "Re: [PATCH v7 4/4] Bluetooth: btqca: inject command complete event during fw download"
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