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

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Message-ID: <02aa65e7-e967-055b-2af3-2e9b6ef77935@nvidia.com>
Date:   Tue, 19 Sep 2017 14:44:36 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Brian Norris <briannorris@...omium.org>,
        Olof Johansson <olof@...om.net>,
        Benson Leung <bleung@...omium.org>
CC:     Lee Jones <lee.jones@...aro.org>, <linux-kernel@...r.kernel.org>,
        "Doug Anderson" <dianders@...omium.org>,
        Brian Norris <computersforpeace@...il.com>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Shawn Nematbakhsh <shawnn@...omium.org>,
        Gwendal Grignou <gwendal@...omium.org>,
        Enric Balletbo <enric.balletbo@...labora.co.uk>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v3] platform/chrome: Use proper protocol transfer function

Hi Brian,

On 08/09/17 21:50, Brian Norris wrote:
> From: Shawn Nematbakhsh <shawnn@...omium.org>
> 
> 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@...omium.org>
> Signed-off-by: Brian Norris <briannorris@...omium.org>
> Reviewed-by: Javier Martinez Canillas <javier@....samsung.com>
> ---
> 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;
>  
> +	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.

Cheers
Jon

[0]
https://nvtb.github.io//linux-next/test_next-20170919/20170918213034/boot/tegra124-nyan-big/tegra124-nyan-big/tegra_defconfig_log.txt


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