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Date:   Mon, 18 Jun 2018 08:44:43 +0100
From:   Lee Jones <lee.jones@linaro.org>
To:     Neil Armstrong <narmstrong@baylibre.com>
Cc:     airlied@linux.ie, hans.verkuil@cisco.com, olof@lixom.net,
        seanpaul@google.com, sadolfsson@google.com, felixe@google.com,
        bleung@google.com, darekm@google.com, marcheu@chromium.org,
        fparent@baylibre.com, dri-devel@lists.freedesktop.org,
        linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, eballetbo@gmail.com,
        Stefan Adolfsson <sadolfsson@chromium.org>
Subject: Re: [PATCH v7 3/6] mfd: cros-ec: Increase maximum mkbp event size
Message-ID: <20180618074443.GK31141@dell>
References: <1527841154-24832-1-git-send-email-narmstrong@baylibre.com>
 <1527841154-24832-4-git-send-email-narmstrong@baylibre.com>
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On Fri, 01 Jun 2018, Neil Armstrong wrote:

> Having a 16 byte mkbp event size makes it possible to send CEC
> messages from the EC to the AP directly inside the mkbp event
> instead of first doing a notification and then a read.
> 
> Signed-off-by: Stefan Adolfsson <sadolfsson@chromium.org>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> Tested-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> ---
>  drivers/platform/chrome/cros_ec_proto.c | 40 +++++++++++++++++++++++++--------
>  include/linux/mfd/cros_ec.h             |  2 +-
>  include/linux/mfd/cros_ec_commands.h    | 19 ++++++++++++++++
>  3 files changed, 51 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> index e7bbdf9..c4f6c44 100644
> --- a/drivers/platform/chrome/cros_ec_proto.c
> +++ b/drivers/platform/chrome/cros_ec_proto.c
> @@ -504,10 +504,31 @@ int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
>  }
>  EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
>  
> +static int get_next_event_xfer(struct cros_ec_device *ec_dev,
> +			       struct cros_ec_command *msg,
> +			       int version, uint32_t size)
> +{
> +	int ret;
> +
> +	msg->version = version;
> +	msg->command = EC_CMD_GET_NEXT_EVENT;
> +	msg->insize = size;
> +	msg->outsize = 0;
> +
> +	ret = cros_ec_cmd_xfer(ec_dev, msg);
> +	if (ret > 0) {
> +		ec_dev->event_size = ret - 1;
> +		memcpy(&ec_dev->event_data, msg->data, ec_dev->event_size);
> +	}
> +
> +	return ret;
> +}
> +
>  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;
>  
>  	if (ec_dev->suspended) {
> @@ -515,18 +536,19 @@ static int get_next_event(struct cros_ec_device *ec_dev)
>  		return -EHOSTDOWN;
>  	}
>  
> -	msg->version = 0;
> -	msg->command = EC_CMD_GET_NEXT_EVENT;
> -	msg->insize = sizeof(ec_dev->event_data);
> -	msg->outsize = 0;
> +	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;
>  
> -	ret = cros_ec_cmd_xfer(ec_dev, msg);
> -	if (ret > 0) {
> -		ec_dev->event_size = ret - 1;
> -		memcpy(&ec_dev->event_data, msg->data,
> -		       sizeof(ec_dev->event_data));
> +		/* Fallback to version 0 for future send attempts */
> +		cmd_version = 0;
>  	}
>  
> +	ret = get_next_event_xfer(ec_dev, msg, cmd_version,
> +				  sizeof(struct ec_response_get_next_event));
> +
>  	return ret;
>  }
>  
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index f36125e..32caef3 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -147,7 +147,7 @@ struct cros_ec_device {
>  	bool mkbp_event_supported;
>  	struct blocking_notifier_head event_notifier;
>  
> -	struct ec_response_get_next_event event_data;
> +	struct ec_response_get_next_event_v1 event_data;
>  	int event_size;
>  	u32 host_event_wake_mask;
>  };
> diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
> index f2edd99..cc0768e 100644
> --- a/include/linux/mfd/cros_ec_commands.h
> +++ b/include/linux/mfd/cros_ec_commands.h
> @@ -2093,12 +2093,31 @@ union ec_response_get_next_data {
>  	uint32_t   sysrq;
>  } __packed;
>  
> +union ec_response_get_next_data_v1 {
> +	uint8_t   key_matrix[16];
> +
> +	/* Unaligned */

That's funny!

> +	uint32_t  host_event;
> +
> +	uint32_t   buttons;
> +	uint32_t   switches;
> +	uint32_t   sysrq;
> +	uint32_t   cec_events;
> +	uint8_t    cec_message[16];

Since there are some whitespace alignment issues in here.

> +} __packed;

How come these guys have kerneldoc headers?

>  struct ec_response_get_next_event {
>  	uint8_t event_type;
>  	/* Followed by event data if any */
>  	union ec_response_get_next_data data;
>  } __packed;
>  
> +struct ec_response_get_next_event_v1 {
> +	uint8_t event_type;
> +	/* Followed by event data if any */
> +	union ec_response_get_next_data_v1 data;
> +} __packed;
> +
>  /* Bit indices for buttons and switches.*/
>  /* Buttons */
>  #define EC_MKBP_POWER_BUTTON	0

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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