Re: [PATCH v3] platform/chrome: Use proper protocol transfer function

From: Jon Hunter
Date: Tue Sep 19 2017 - 12:42:33 EST




On 19/09/17 15:09, Shawn N wrote:
> On Tue, Sep 19, 2017 at 6:44 AM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:
>>
>> Hi Brian,
>>
>> On 08/09/17 21:50, Brian Norris wrote:
>>> From: Shawn Nematbakhsh <shawnn@xxxxxxxxxxxx>
>>>
>>> pkt_xfer should be used for protocol v3, and cmd_xfer otherwise. We had
>>> one instance of these functions correct, but not the second, fall-back
>>> case. We use the fall-back only when the first command returns an
>>> IN_PROGRESS status, which is only used on some EC firmwares where we
>>> don't want to constantly poll the bus, but instead back off and
>>> sleep/retry for a little while.
>>>
>>> Fixes: 2c7589af3c4d ("mfd: cros_ec: add proto v3 skeleton")
>>> Signed-off-by: Shawn Nematbakhsh <shawnn@xxxxxxxxxxxx>
>>> Signed-off-by: Brian Norris <briannorris@xxxxxxxxxxxx>
>>> Reviewed-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
>>> ---
>>> v3:
>>> * Added Javier's reviewed tag
>>> * It's been > 8 months since [1], so why not? And hey, Benson's officially in
>>> MAINTAINERS now! Too bad no one told me.
>>>
>>> [1] https://patchwork.kernel.org/patch/9450633/
>>>
>>>
>>> v2:
>>> * Add Benson in 'To:'
>>> * make subject prefix more obvious
>>>
>>> drivers/platform/chrome/cros_ec_proto.c | 8 +++++---
>>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
>>> index 8dfa7fcb1248..e7bbdf947bbc 100644
>>> --- a/drivers/platform/chrome/cros_ec_proto.c
>>> +++ b/drivers/platform/chrome/cros_ec_proto.c
>>> @@ -60,12 +60,14 @@ static int send_command(struct cros_ec_device *ec_dev,
>>> struct cros_ec_command *msg)
>>> {
>>> int ret;
>>> + int (*xfer_fxn)(struct cros_ec_device *ec, struct cros_ec_command *msg);
>>>
>>> if (ec_dev->proto_version > 2)
>>> - ret = ec_dev->pkt_xfer(ec_dev, msg);
>>> + xfer_fxn = ec_dev->pkt_xfer;
>>> else
>>> - ret = ec_dev->cmd_xfer(ec_dev, msg);
>>> + xfer_fxn = ec_dev->cmd_xfer;u
>>>
>>> + ret = (*xfer_fxn)(ec_dev, msg);
>>> if (msg->result == EC_RES_IN_PROGRESS) {
>>> int i;
>>> struct cros_ec_command *status_msg;
>>> @@ -88,7 +90,7 @@ static int send_command(struct cros_ec_device *ec_dev,
>>> for (i = 0; i < EC_COMMAND_RETRIES; i++) {
>>> usleep_range(10000, 11000);
>>>
>>> - ret = ec_dev->cmd_xfer(ec_dev, status_msg);
>>> + ret = (*xfer_fxn)(ec_dev, status_msg);
>>> if (ret < 0)
>>> break;
>>>
>>
>> Tegra124 Nyan-Big is currently crashing during boot with -next [0] and
>> bisect is pointing to this commit. Reverting the above on top of -next
>> does allow the board to boot successfully. Looks like this board is
>> proto_version 3 but I have not looked into this any further. Let me know
>> if you have any thoughts.
>
>
> Thanks for the bug report, I'll look into this today.
>
>> [ 1.502497] kernel BUG at drivers/platform/chrome/cros_ec_proto.c:34!
>> 34 BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
>
> So, ec_dev->proto_version > 3? That doesn't seem right.

You mean != 3, but yes. Looks like an initialisation problem, because if I
add the following WARNING ...

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index e7bbdf947bbc..ad3b3a1e8d54 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -31,6 +31,7 @@ static int prepare_packet(struct cros_ec_device *ec_dev,
int i;
u8 csum = 0;

+ WARN(ec_dev->proto_version != EC_HOST_REQUEST_VERSION, "%d != %d", ec_dev->proto_version, EC_HOST_REQUEST_VERSION);
BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
BUG_ON(msg->outsize + sizeof(*request) > ec_dev->dout_size);

... then I see ...

[ 1.502495] WARNING: CPU: 0 PID: 1 at drivers/platform/chrome/cros_ec_proto.c:35 cros_ec_prepare_tx+0x190/0x1a8
[ 1.512566] 65535 != 3

Any chance this is being called before the version is initialised?

Cheers
Jon

--
nvpublic