Date:   Wed, 13 Apr 2022 16:00:42 -0700
From:   "Martinez, Ricardo" <ricardo.martinez@...ux.intel.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     Netdev <netdev@...r.kernel.org>, linux-wireless@...r.kernel.org,
        kuba@...nel.org, davem@...emloft.net, johannes@...solutions.net,
        ryazanov.s.a@...il.com, loic.poulain@...aro.org,
        m.chetan.kumar@...el.com, chandrashekar.devegowda@...el.com,
        linuxwwan@...el.com, chiranjeevi.rapolu@...ux.intel.com,
        haijun.liu@...iatek.com, amir.hanania@...el.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        dinesh.sharma@...el.com, eliot.lee@...el.com,
        moises.veleta@...el.com, pierre-louis.bossart@...el.com,
        muralidharan.sethuraman@...el.com, Soumya.Prakash.Mishra@...el.com,
        sreehari.kancharla@...el.com, madhusmita.sahu@...el.com
Subject: Re: [PATCH net-next v6 05/13] net: wwan: t7xx: Add control port


On 4/12/2022 5:04 AM, Ilpo Järvinen wrote:
> On Thu, 7 Apr 2022, Ricardo Martinez wrote:
>
>> From: Haijun Liu <haijun.liu@...iatek.com>
>>
>> Control Port implements driver control messages such as modem-host
>> handshaking, controls port enumeration, and handles exception messages.
>>
>> The handshaking process between the driver and the modem happens during
>> the init sequence. The process involves the exchange of a list of
>> supported runtime features to make sure that modem and host are ready
>> to provide proper feature lists including port enumeration. Further
>> features can be enabled and controlled in this handshaking process.
>>
>> Signed-off-by: Haijun Liu <haijun.liu@...iatek.com>
>> Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@...el.com>
>> Co-developed-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
>> Signed-off-by: Ricardo Martinez <ricardo.martinez@...ux.intel.com>
>>
>> >From a WWAN framework perspective:
>> Reviewed-by: Loic Poulain <loic.poulain@...aro.org>
>>
>> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
>> +static int t7xx_prepare_device_rt_data(struct t7xx_sys_info *core, struct device *dev,
>> +				       void *data)
>> +{
>> +	struct feature_query *md_feature = data;
>> +	struct mtk_runtime_feature *rt_feature;
>> +	unsigned int i, rt_data_len = 0;
>> +	struct sk_buff *skb;
>> +
>> +	/* Parse MD runtime data query */
>> +	if (le32_to_cpu(md_feature->head_pattern) != MD_FEATURE_QUERY_ID ||
>> +	    le32_to_cpu(md_feature->tail_pattern) != MD_FEATURE_QUERY_ID) {
>> +		dev_err(dev, "Invalid feature pattern: head 0x%x, tail 0x%x\n",
>> +			le32_to_cpu(md_feature->head_pattern),
>> +			le32_to_cpu(md_feature->tail_pattern));
>> +		return -EINVAL;
>> +	}
>> +
>> +	for (i = 0; i < FEATURE_COUNT; i++) {
>> +		if (FIELD_GET(FEATURE_MSK, md_feature->feature_set[i]) !=
>> +		    MTK_FEATURE_MUST_BE_SUPPORTED)
>> +			rt_data_len += sizeof(*rt_feature);
>> +	}
>> +
>> +	skb = t7xx_ctrl_alloc_skb(rt_data_len);
>> +	if (!skb)
>> +		return -ENOMEM;
>> +
>> +	rt_feature  = skb_put(skb, rt_data_len);
>> +	memset(rt_feature, 0, rt_data_len);
>> +
>> +	/* Fill runtime feature */
>> +	for (i = 0; i < FEATURE_COUNT; i++) {
>> +		u8 md_feature_mask = FIELD_GET(FEATURE_MSK, md_feature->feature_set[i]);
>> +
>> +		if (md_feature_mask == MTK_FEATURE_MUST_BE_SUPPORTED)
>> +			continue;
>> +
>> +		rt_feature->feature_id = i;
>> +		if (md_feature_mask == MTK_FEATURE_DOES_NOT_EXIST)
>> +			rt_feature->support_info = md_feature->feature_set[i];
>> +
>> +		rt_feature++;
>> +	}
>> +
>> +	/* Send HS3 message to device */
>> +	t7xx_port_send_ctl_skb(core->ctl_port, skb, CTL_ID_HS3_MSG, 0);
>> +	return 0;
>> +}
>> +
>> +static int t7xx_parse_host_rt_data(struct t7xx_fsm_ctl *ctl, struct t7xx_sys_info *core,
>> +				   struct device *dev, void *data, int data_length)
>> +{
>> +	enum mtk_feature_support_type ft_spt_st, ft_spt_cfg;
>> +	struct mtk_runtime_feature *rt_feature;
>> +	int i, offset;
>> +
>> +	offset = sizeof(struct feature_query);
>> +	for (i = 0; i < FEATURE_COUNT && offset < data_length; i++) {
>> +		rt_feature = data + offset;
>> +		offset += sizeof(*rt_feature) + le32_to_cpu(rt_feature->data_len);
>> +
>> +		ft_spt_cfg = FIELD_GET(FEATURE_MSK, core->feature_set[i]);
>> +		if (ft_spt_cfg != MTK_FEATURE_MUST_BE_SUPPORTED)
>> +			continue;
> Do MTK_FEATURE_MUST_BE_SUPPORTED appear in the host rt_features
> (unlike in the device rt_features)?
>
Yes, in the first step of the handshake protocol, the host creates its
rt_feature list with the proper support label and sends the list to the device.
t7xx_parse_host_rt_data() is part of the handshake step 2, the host received the
response from the device and now it will verify that the host rt_features
labeled as MTK_FEATURE_MUST_BE_SUPPORTED are also supported in the device rt_features.

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