netdev - Re: [PATCH v2 06/14] net: wwan: t7xx: Add AT and MBIM WWAN ports

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Message-ID: <a9f1237c-78d5-d64e-6980-a7c7c5f6f5f9@linux.intel.com>
Date:   Tue, 30 Nov 2021 22:14:55 -0800
From:   "Martinez, Ricardo" <ricardo.martinez@...ux.intel.com>
To:     Sergey Ryazanov <ryazanov.s.a@...il.com>
Cc:     netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        Johannes Berg <johannes@...solutions.net>,
        Loic Poulain <loic.poulain@...aro.org>,
        M Chetan Kumar <m.chetan.kumar@...el.com>,
        chandrashekar.devegowda@...el.com,
        Intel Corporation <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,
        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 v2 06/14] net: wwan: t7xx: Add AT and MBIM WWAN ports


On 11/9/2021 4:06 AM, Sergey Ryazanov wrote:
> On Mon, Nov 1, 2021 at 6:57 AM Ricardo Martinez wrote:
>> ...
>>   static struct t7xx_port md_ccci_ports[] = {
>> +       {CCCI_UART2_TX, CCCI_UART2_RX, DATA_AT_CMD_Q, DATA_AT_CMD_Q, 0xff,
>> +        0xff, ID_CLDMA1, PORT_F_RX_CHAR_NODE, &wwan_sub_port_ops, 0, "ttyC0", WWAN_PORT_AT},
>> +       {CCCI_MBIM_TX, CCCI_MBIM_RX, 2, 2, 0, 0, ID_CLDMA1,
>> +        PORT_F_RX_CHAR_NODE, &wwan_sub_port_ops, 10, "ttyCMBIM0", WWAN_PORT_MBIM},
>> ...
>> +               if (count + CCCI_H_ELEN > txq_mtu &&
>> +                   (port_ccci->tx_ch == CCCI_MBIM_TX ||
>> +                    (port_ccci->tx_ch >= CCCI_DSS0_TX && port_ccci->tx_ch <= CCCI_DSS7_TX)))
>> +                       multi_packet = DIV_ROUND_UP(count, txq_mtu - CCCI_H_ELEN);
> I am just wondering, the chip does support MBIM message fragmentation,
> but does not support AT commands stream (CCCI_UART2_TX) fragmentation.
> Is that the correct conclusion from the code above?
Yes, that is correct.
>
> BTW, you could factor out data fragmentation support to a dedicated
> function to improve code readability. Something like this:
>
> static inline bool port_is_multipacket_capable(... *port)
> {
>          return port->tx_ch == CCCI_MBIM_TX ||
>                 (port->tx_ch >= CCCI_DSS0_TX && port->tx_ch <= CCCI_DSS7_TX);
> }
>
> So condition become something like that:
>
>          if (count + CCCI_H_ELEN > txq_mtu &&
>              port_is_multipacket_capable(port))
>                  multi_packet = DIV_ROUND_UP(count, txq_mtu - CCCI_H_ELEN);

Ricardo