Messages in this thread | | | From | Gwendal Grignou <> | Date | Tue, 3 Dec 2019 11:20:21 -0800 | Subject | Re: [PATCH v4] mfd / platform: cros_ec: Query EC protocol version if EC transitions between RO/RW |
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On Tue, Nov 26, 2019 at 1:56 AM Enric Balletbo i Serra <enric.balletbo@collabora.com> wrote: > > Hi Yicheng, > > I looked at this patch deeply and I have a question. > > On 25/11/19 23:15, Yicheng Li wrote: > > RO and RW of EC may have different EC protocol version. If EC transitions > > between RO and RW, but AP does not reboot (this is true for fingerprint > > microcontroller / cros_fp, but not true for main ec / cros_ec), the AP > > still uses the protocol version queried before transition, which can > > cause problems. In the case of fingerprint microcontroller, this causes > > AP to send the wrong version of EC_CMD_GET_NEXT_EVENT to RO in the > > interrupt handler, which in turn prevents RO to clear the interrupt > > line to AP, in an infinite loop. > > > > Once an EC_HOST_EVENT_INTERFACE_READY is received, we know that there > > might have been a transition between RO and RW, so re-query the protocol. > > > > Signed-off-by: Yicheng Li <yichengli@chromium.org> > > --- > > drivers/platform/chrome/cros_ec.c | 24 +++++++++++++++++++++ > > include/linux/platform_data/cros_ec_proto.h | 3 +++ > > 2 files changed, 27 insertions(+) > > > > diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c > > index 9b2d07422e17..38ec1fb409a5 100644 > > --- a/drivers/platform/chrome/cros_ec.c > > +++ b/drivers/platform/chrome/cros_ec.c > > @@ -104,6 +104,23 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event) > > return ret; > > } > > > > +static int cros_ec_ready_event(struct notifier_block *nb, > > + unsigned long queued_during_suspend, void *_notify) > > +{ > > + struct cros_ec_device *ec_dev = container_of(nb, struct cros_ec_device, > > + notifier_ready); > > + u32 host_event = cros_ec_get_host_event(ec_dev); > > + > > + if (host_event & EC_HOST_EVENT_MASK(EC_HOST_EVENT_INTERFACE_READY)) { > > + mutex_lock(&ec_dev->lock); > > + cros_ec_query_all(ec_dev); > > I am wondering if instead of calling cros_ec_query_all we can just set the proto > version to unknown: > > ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN > > and let the cros_ec_cmd_xfer function do its magic.
This has actually been used in cros_ec_query_all itself, when the EC is not responding: when cros_ec_cmd_xfer is called, cros_ec_query_all() is called again. This is used when cros_ec_query_all() is called cros_ec_register(), but this is not working properly anymore, because the irq and device driver will not be registered anymore. See in cros_ec_register when cros_ec_query_all is called and set _UNKNOWN, ret is not 0 and cros_ec_register() will bail. I will work on it later. (crbug.com/1030373 for reference).
For our case at hand, we can not wait for a command coming from user space to unlock us. Internal commands could use send_command directly, if a new interrupt comes up for instance). Let's put all the check code from cros_ec_cmd_xfer() in send_command() and indeed reset the proto_version.
Gwendal.
> > Should that work? > > Thanks, > Enric > > > + mutex_unlock(&ec_dev->lock); > > + return NOTIFY_OK; > > + } > > + > > + return NOTIFY_DONE; > > +} > > + > > /** > > * cros_ec_register() - Register a new ChromeOS EC, using the provided info. > > * @ec_dev: Device to register. > > @@ -201,6 +218,13 @@ int cros_ec_register(struct cros_ec_device *ec_dev) > > dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec", > > err); > > > > + /* Register the notifier for EC_HOST_EVENT_INTERFACE_READY event. */ > > + ec_dev->notifier_ready.notifier_call = cros_ec_ready_event; > > + err = blocking_notifier_chain_register(&ec_dev->event_notifier, > > + &ec_dev->notifier_ready); > > + if (err) > > + return err; > > + > > dev_info(dev, "Chrome EC device registered\n"); > > > > return 0; > > diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h > > index 0d4e4aaed37a..a1c545c464e7 100644 > > --- a/include/linux/platform_data/cros_ec_proto.h > > +++ b/include/linux/platform_data/cros_ec_proto.h > > @@ -121,6 +121,8 @@ struct cros_ec_command { > > * @event_data: Raw payload transferred with the MKBP event. > > * @event_size: Size in bytes of the event data. > > * @host_event_wake_mask: Mask of host events that cause wake from suspend. > > + * @notifier_ready: The notifier_block to let the kernel re-query EC > > + * communication protocol when the EC sends EC_HOST_EVENT_INTERFACE_READY. > > * @ec: The platform_device used by the mfd driver to interface with the > > * main EC. > > * @pd: The platform_device used by the mfd driver to interface with the > > @@ -161,6 +163,7 @@ struct cros_ec_device { > > int event_size; > > u32 host_event_wake_mask; > > u32 last_resume_result; > > + struct notifier_block notifier_ready; > > > > /* The platform devices used by the mfd driver */ > > struct platform_device *ec; > >
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