Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <533b62f7-a6c2-b360-13e0-b873a1a54251@broadcom.com>
Date:   Mon, 14 Aug 2023 09:28:02 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0)
 Gecko/20100101 Thunderbird/102.13.0
Subject: Re: [PATCH] serial: 8250_bcm7271: improve bcm7271 8250 port
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-serial@vger.kernel.org, opendmb@gmail.com,
        Al Cooper <alcooperx@gmail.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@broadcom.com>,
        Jiri Slaby <jirislaby@kernel.org>,
        =?UTF-8?Q?Ilpo_J=c3=a4rvinen?= <ilpo.jarvinen@linux.intel.com>,
        John Ogness <john.ogness@linutronix.de>,
        Jiaqing Zhao <jiaqing.zhao@linux.intel.com>,
        "open list:TTY LAYER" <linux-kernel@vger.kernel.org>
References: <1691792050-25042-1-git-send-email-justin.chen@broadcom.com>
 <2023081221-truth-footsie-b5ab@gregkh>
 <CALSSxFZyQCCupuXC7=z3yoO7xhVY3Grw_zFsdWKrE+txk9-S1Q@mail.gmail.com>
 <ZNpEe+nmXGAkEbAb@smile.fi.intel.com>
From:   Justin Chen <justin.chen@broadcom.com>
In-Reply-To: <ZNpEe+nmXGAkEbAb@smile.fi.intel.com>
Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256;
        boundary="000000000000181e9e0602e48cc8"
Precedence: bulk

--000000000000181e9e0602e48cc8
Content-Language: en-US
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit


On 8/14/23 8:12 AM, Andy Shevchenko wrote:
> On Sat, Aug 12, 2023 at 09:24:21PM -0700, Justin Chen wrote:
>> On Sat, Aug 12, 2023 at 3:50 AM Greg Kroah-Hartman
>> <gregkh@linuxfoundation.org> wrote:
>>> On Fri, Aug 11, 2023 at 03:14:01PM -0700, Justin Chen wrote:
> 
>>>> +     [PORT_BCM7271] = {
>>>> +             .name           = "bcm7271_uart",
> 
> This is badly named port type.
> 

Would "Brcmstb 7271 UART" suffice?

>>>> +             .fifo_size      = 32,
>>>> +             .tx_loadsz      = 32,
>>>> +             .fcr            = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_01,
>>>> +             .rxtrig_bytes   = {1, 8, 16, 30},
>>>> +             .flags          = UART_CAP_FIFO | UART_CAP_AFE
>>>> +     },
>>>>   };
> 
> This is almost a dup of PORT_ALTR_16550_F32. Use it if you wish.
> You can always rename it if it feels the right thing to do.
> 

There is some other PORT_ALTR logic that I would like to avoid. I would 
also like to avoid future changes to PORT_ALTR that wouldn't be 
applicable to us.

> But why 8 and not 16 is the default rxtrig?
> 

We were seeing some latency issues on our chips where 16 would cause 
overflows. Trying to kill 2 birds with one stone. If creating another 
port type is avoidable then alternatively I can change the default in 
userspace.

Thanks,
Justin

--000000000000181e9e0602e48cc8
Content-Type: application/pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
Content-Description: S/MIME Cryptographic Signature
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--000000000000181e9e0602e48cc8--