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SubjectRe: [PATCH] mfd: cros_ec: Add support for MKBP more event flags
On Fri, Dec 7, 2018 at 2:22 PM Brian Norris <briannorris@chromium.org> wrote:
>
> Hi Enrico,
>
> On Thu, Nov 29, 2018 at 11:55:48AM -0800, egranata@google.com wrote:
> > From: Enrico Granata <egranata@chromium.org>
> >
> > The ChromeOS EC has support for signaling to the host that
> > a single IRQ can serve multiple MKBP events.
> >
> > Doing this serves an optimization purpose, as it minimizes the
> > number of round-trips into the interrupt handling machinery, and
> > it proves beneficial to sensor timestamping as it keeps the desired
> > synchronization of event times between the two processors.
> >
> > This patch adds kernel support for this EC feature, allowing the
> > ec_irq to loop until all events have been served.
>
> Might be worth being more explicit in this commit message to say that
> you're adding support for EC_CMD_GET_NEXT_EVENT version 2?
>
> > Signed-off-by: Enrico Granata <egranata@chromium.org>
>
> Mostly looks fine; thanks for sending. I have a few small notes (and
> some of that is not necessarily something resolve in this patch), but
> with at least the cros_ec.h comment fixup, feel free to add my:
>
> Reviewed-by: Brian Norris <briannorris@chromium.org>
>
> > ---
> > drivers/mfd/cros_ec.c | 20 +++++++++++++--
> > drivers/platform/chrome/cros_ec_proto.c | 33 +++++++++++--------------
> > include/linux/mfd/cros_ec.h | 3 ++-
> > include/linux/mfd/cros_ec_commands.h | 15 +++++++++++
> > 4 files changed, 50 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> > index fe6f83766144f..17903a378aa1a 100644
> > --- a/drivers/mfd/cros_ec.c
> > +++ b/drivers/mfd/cros_ec.c
> > @@ -51,13 +51,16 @@ static const struct mfd_cell ec_pd_cell = {
> > .pdata_size = sizeof(pd_p),
> > };
> >
> > -static irqreturn_t ec_irq_thread(int irq, void *data)
> > +static bool ec_handle_event(struct cros_ec_device *ec_dev)
> > {
> > - struct cros_ec_device *ec_dev = data;
> > bool wake_event = true;
> > int ret;
> > + bool ec_has_more_events = false;
> >
> > ret = cros_ec_get_next_event(ec_dev, &wake_event);
> > + if (ret > 0)
> > + ec_has_more_events =
> > + ec_dev->event_data.event_type & EC_MKBP_HAS_MORE_EVENTS;
> >
> > /*
> > * Signal only if wake host events or any interrupt if
> > @@ -70,6 +73,19 @@ static irqreturn_t ec_irq_thread(int irq, void *data)
> > if (ret > 0)
> > blocking_notifier_call_chain(&ec_dev->event_notifier,
> > 0, ec_dev);
> > +
> > + return ec_has_more_events;
> > +}
> > +
> > +static irqreturn_t ec_irq_thread(int irq, void *data)
> > +{
> > + struct cros_ec_device *ec_dev = data;
> > + bool ec_has_more_events;
> > +
> > + do {
> > + ec_has_more_events = ec_handle_event(ec_dev);
> > + } while (ec_has_more_events);
> > +
> > return IRQ_HANDLED;
> > }
> >
> > diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> > index b6fd4838f60f3..bb126d95b2fd4 100644
> > --- a/drivers/platform/chrome/cros_ec_proto.c
> > +++ b/drivers/platform/chrome/cros_ec_proto.c
> > @@ -420,10 +420,14 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev)
> > ret = cros_ec_get_host_command_version_mask(ec_dev,
> > EC_CMD_GET_NEXT_EVENT,
> > &ver_mask);
>
> It's not exactly new here (although you're using 'ver_mask' in new
> ways), but cros_ec_get_host_command_version_mask() doesn't look 100%
> right. It doesn't look at msg->result, and instead just assumes that if
> we got some data back (send_command() > 0), then it must have been a
> success. I don't think that's really guaranteed in general, although it
> might be for the specific case of EC_CMD_GET_CMD_VERSIONS.
It is guaranteed: if msg->result is not EC_RES_SUCCESS, then ret can
not be greater than 0. At best it will be 0, or a negative number if
we can already qualify the error in the errno space (see
cros_ec_pkt_xfer_i2c() for instance).

Gwendal.
>
> IOW, to be definitely sure we're not looking at a garbage result in
> 'ver_mask', we should probably fixup
> cros_ec_get_host_command_version_mask().
>
> > - if (ret < 0 || ver_mask == 0)
> > + if (ret < 0 || ver_mask == 0) {
> > ec_dev->mkbp_event_supported = 0;
> > - else
> > - ec_dev->mkbp_event_supported = 1;
> > + dev_info(ec_dev->dev, "MKBP not supported\n");
> > + } else {
> > + ec_dev->mkbp_event_supported = fls(ver_mask);
> > + dev_info(ec_dev->dev, "MKBP support version %u\n",
> > + ec_dev->mkbp_event_supported - 1);
> > + }
> >
> > /*
> > * Get host event wake mask, assume all events are wake events
> > @@ -530,28 +534,19 @@ static int get_next_event(struct cros_ec_device *ec_dev)
> > {
> > u8 buffer[sizeof(struct cros_ec_command) + sizeof(ec_dev->event_data)];
> > struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
> > - static int cmd_version = 1;
> > - int ret;
> > + const int cmd_version = ec_dev->mkbp_event_supported - 1;
> >
> > if (ec_dev->suspended) {
> > dev_dbg(ec_dev->dev, "Device suspended.\n");
> > return -EHOSTDOWN;
> > }
> >
> > - if (cmd_version == 1) {
> > - ret = get_next_event_xfer(ec_dev, msg, cmd_version,
> > - sizeof(struct ec_response_get_next_event_v1));
> > - if (ret < 0 || msg->result != EC_RES_INVALID_VERSION)
> > - return ret;
> > -
> > - /* Fallback to version 0 for future send attempts */
> > - cmd_version = 0;
> > - }
> > -
> > - ret = get_next_event_xfer(ec_dev, msg, cmd_version,
> > + if (cmd_version == 0)
> > + return get_next_event_xfer(ec_dev, msg, 0,
> > sizeof(struct ec_response_get_next_event));
> >
> > - return ret;
> > + return get_next_event_xfer(ec_dev, msg, cmd_version,
> > + sizeof(struct ec_response_get_next_event_v1));
> > }
> >
> > static int get_keyboard_state_event(struct cros_ec_device *ec_dev)
> > @@ -607,11 +602,13 @@ EXPORT_SYMBOL(cros_ec_get_next_event);
> >
> > u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev)
> > {
> > + u32 event_type =
> > + ec_dev->event_data.event_type & EC_MKBP_EVENT_TYPE_MASK;
> > u32 host_event;
> >
> > BUG_ON(!ec_dev->mkbp_event_supported);
> >
> > - if (ec_dev->event_data.event_type != EC_MKBP_EVENT_HOST_EVENT)
> > + if (event_type != EC_MKBP_EVENT_HOST_EVENT)
> > return 0;
> >
> > if (ec_dev->event_size != sizeof(host_event)) {
> > diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> > index e44e3ec8a9c7d..eb771ceeaeed1 100644
> > --- a/include/linux/mfd/cros_ec.h
> > +++ b/include/linux/mfd/cros_ec.h
> > @@ -152,7 +152,8 @@ struct cros_ec_device {
> > int (*pkt_xfer)(struct cros_ec_device *ec,
> > struct cros_ec_command *msg);
> > struct mutex lock;
> > - bool mkbp_event_supported;
> > + /* 0 == not supported, otherwise it supports version x - 1 */
>
> This comment belongs in the kerneldoc, which is above the struct
> definition. You're invalidating the existing comment:
>
> * @mkbp_event_supported: True if this EC supports the MKBP event protocol.
>
> Brian
>
>
> > + u8 mkbp_event_supported;
> > struct blocking_notifier_head event_notifier;
> >
> > struct ec_response_get_next_event_v1 event_data;
>
> ...

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