netdev - Re: [PATCH net-next v3 05/12] net: wwan: t7xx: Add AT and MBIM WWAN ports

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Message-ID: <66e09242-ee3e-f714-a9b9-d3ee80ef6596@linux.intel.com>
Date:   Thu, 16 Dec 2021 14:25:47 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Ricardo Martinez <ricardo.martinez@...ux.intel.com>
cc:     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,
        andriy.shevchenko@...ux.intel.com, dinesh.sharma@...el.com,
        eliot.lee@...el.com, mika.westerberg@...ux.intel.com,
        moises.veleta@...el.com, pierre-louis.bossart@...el.com,
        muralidharan.sethuraman@...el.com, Soumya.Prakash.Mishra@...el.com,
        sreehari.kancharla@...el.com, suresh.nagaraj@...el.com
Subject: Re: [PATCH net-next v3 05/12] net: wwan: t7xx: Add AT and MBIM WWAN
 ports

On Mon, 6 Dec 2021, Ricardo Martinez wrote:

> From: Chandrashekar Devegowda <chandrashekar.devegowda@...el.com>
> 
> Adds AT and MBIM ports to the port proxy infrastructure.
> The initialization method is responsible for creating the corresponding
> ports using the WWAN framework infrastructure. The implemented WWAN port
> operations are start, stop, and TX.
> 
> 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>

> +static int t7xx_port_ctrl_tx(struct wwan_port *port, struct sk_buff *skb)
> +{
> +	struct t7xx_port *port_private = wwan_port_get_drvdata(port);
> +	size_t actual_count = 0, alloc_size = 0, txq_mtu = 0;
> +	struct t7xx_port_static *port_static;
> +	int i, multi_packet = 1, ret = 0;
> +	struct sk_buff *skb_ccci = NULL;
> +	struct t7xx_fsm_ctl *ctl;
> +	enum md_state md_state;
> +	unsigned int count;
> +	bool port_multi;
> +
> +	count = skb->len;
> +	if (!count)
> +		return -EINVAL;
> +
> +	port_static = port_private->port_static;
> +	ctl = port_private->t7xx_dev->md->fsm_ctl;
> +	md_state = t7xx_fsm_get_md_state(ctl);
> +	if (md_state == MD_STATE_WAITING_FOR_HS1 || md_state == MD_STATE_WAITING_FOR_HS2) {
> +		dev_warn(port_private->dev, "Cannot write to %s port when md_state=%d\n",
> +			 port_static->name, md_state);
> +		return -ENODEV;
> +	}
> +
> +	txq_mtu = CLDMA_TXQ_MTU;
> +
> +	if (port_private->flags & PORT_F_USER_HEADER) {
> +		if (port_private->flags & PORT_F_USER_HEADER && count > txq_mtu) {
> +			dev_err(port_private->dev, "Packet %u larger than MTU on %s port\n",
> +				count, port_static->name);
> +			return -ENOMEM;
> +		}
> +
> +		alloc_size = min_t(size_t, txq_mtu, count);
> +		actual_count = alloc_size;
> +	} else {
> +		alloc_size = min_t(size_t, txq_mtu, count + CCCI_H_ELEN);
> +		actual_count = alloc_size - CCCI_H_ELEN;
> +		port_multi = t7xx_port_wwan_multipkt_capable(port_static);
> +		if ((count + CCCI_H_ELEN > txq_mtu) && port_multi)
> +			multi_packet = DIV_ROUND_UP(count, txq_mtu - CCCI_H_ELEN);
> +	}
> +
> +	for (i = 0; i < multi_packet; i++) {
> +		struct ccci_header *ccci_h = NULL;
> +
> +		if (multi_packet > 1 && multi_packet == i + 1) {
> +			actual_count = count % (txq_mtu - CCCI_H_ELEN);
> +			alloc_size = actual_count + CCCI_H_ELEN;
> +		}
> +
> +		skb_ccci = __dev_alloc_skb(alloc_size, GFP_KERNEL);
> +		if (!skb_ccci)
> +			return -ENOMEM;
> +
> +		ccci_h = skb_put(skb_ccci, CCCI_H_LEN);
> +		ccci_h->packet_header = 0;
> +		ccci_h->packet_len = cpu_to_le32(actual_count + CCCI_H_LEN);
> +		ccci_h->status &= cpu_to_le32(~HDR_FLD_CHN);
> +		ccci_h->status |= cpu_to_le32(FIELD_PREP(HDR_FLD_CHN, port_static->tx_ch));
> +		ccci_h->ex_msg = 0;
> +
> +		memcpy(skb_put(skb_ccci, actual_count), skb->data + i * (txq_mtu - CCCI_H_ELEN),
> +		       actual_count);
> +
> +		t7xx_port_proxy_set_seq_num(port_private, ccci_h);
> +
> +		ret = t7xx_port_send_skb_to_md(port_private, skb_ccci, true);
> +		if (ret)
> +			goto err_free_skb;
> +
> +		port_private->seq_nums[MTK_TX]++;
> +
> +		if (multi_packet == 1)
> +			return actual_count;
> +		else if (multi_packet == i + 1)
> +			return count;
> +	}

I'd recommend renaming variables to make it clearer what they count:
- count -> bytes
- actual_count -> actual_bytes
- multi_packet -> packets


-- 
 i.