linux-kernel - Re: [PATCH v9 2/2] tty/serial: Add Spreadtrum sc9836-uart driver support

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Message-ID: <CAAfSe-v4FGpHL3N3utiDwcoc7qus1XZZszuXBqB6LeE1frAfeA@mail.gmail.com>
Date:	Wed, 28 Jan 2015 16:46:33 +0800
From:	Lyra Zhang <zhang.lyra@...il.com>
To:	Baruch Siach <baruch@...s.co.il>
Cc:	Chunyan Zhang <chunyan.zhang@...eadtrum.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	Mark Rutland <mark.rutland@....com>,
	"gnomes@...rguk.ukuu.org.uk" <gnomes@...rguk.ukuu.org.uk>,
	Heiko Stübner <heiko@...ech.de>,
	"andrew@...n.ch" <andrew@...n.ch>,
	"jslaby@...e.cz" <jslaby@...e.cz>,
	"lanqing.liu@...eadtrum.com" <lanqing.liu@...eadtrum.com>,
	Arnd Bergmann <arnd@...db.de>,
	"zhizhou.zhang" <zhizhou.zhang@...eadtrum.com>,
	"geng.ren@...eadtrum.com" <geng.ren@...eadtrum.com>,
	"antonynpavlov@...il.com" <antonynpavlov@...il.com>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Orson Zhai <orsonzhai@...il.com>,
	"florian.vaussard@...l.ch" <florian.vaussard@...l.ch>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	Pawel Moll <pawel.moll@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	Hayato Suzuki <hytszk@...il.com>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	Wei Qiao (乔伟) <wei.qiao@...eadtrum.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Peter Hurley <peter@...leysoftware.com>,
	"linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Kumar Gala <galak@...eaurora.org>,
	Shawn Guo <shawn.guo@...aro.org>
Subject: Re: [PATCH v9 2/2] tty/serial: Add Spreadtrum sc9836-uart driver support

Hi, Baruch

I'm sorry that I didn't receive your previous email.
and my explanations are below.

On Wed, Jan 28, 2015 at 2:12 PM, Baruch Siach <baruch@...s.co.il> wrote:
> Hi Chunyan Zhang,
>
> On Wed, Jan 28, 2015 at 10:47:41AM +0800, Chunyan Zhang wrote:
> [...]
>> +static inline void sprd_rx(struct uart_port *port)
>> +{
>> +     struct tty_port *tty = &port->state->port;
>> +     unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
>> +
>> +     while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
>> +             lsr = serial_in(port, SPRD_LSR);
>> +             ch = serial_in(port, SPRD_RXD);
>> +             flag = TTY_NORMAL;
>> +             port->icount.rx++;
>> +
>> +             if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
>> +                     SPRD_LSR_FE | SPRD_LSR_OE))
>> +                     if (handle_lsr_errors(port, &lsr, &flag))
>> +                             continue;
>> +             if (uart_handle_sysrq_char(port, ch))
>> +                     continue;
>
> My comment[1] on a previous version of this patch still stands.
> uart_handle_sysrq_char is a NOP when SUPPORT_SYSRQ is not defined.
>

yes, there are two definitions in serial_core.h, and it returns 0 when
SUPPORT_SYSRQ is not defined.
so, I think my code behavior does not hurt, right?

>> +
>> +             uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
>> +     }
>> +
>> +     tty_flip_buffer_push(tty);
>> +}
>
> [...]
>
>> +static void sprd_console_write(struct console *co, const char *s,
>> +                                   unsigned int count)
>> +{
>> +     struct uart_port *port = &sprd_port[co->index]->port;
>> +     int locked = 1;
>> +     unsigned long flags;
>> +
>> +     if (port->sysrq)
>> +             locked = 0;
>
> The sysrq field of struct uart_port is only defined when
> CONFIG_SERIAL_CORE_CONSOLE or SUPPORT_SYSRQ are defined. You should #ifdef
> this part accordingly to avoid build breakage.
>

we have this part to been included under #ifdef
CONFIG_SERIAL_SPRD_CONSOLE which is selected with SERIAL_CORE_CONSOLE.

Thank you very much!

Chunyan

>> +     else if (oops_in_progress)
>> +             locked = spin_trylock_irqsave(&port->lock, flags);
>> +     else
>> +             spin_lock_irqsave(&port->lock, flags);
>> +
>> +     uart_console_write(port, s, count, sprd_console_putchar);
>> +
>> +     /* wait for transmitter to become empty */
>> +     wait_for_xmitr(port);
>> +
>> +     if (locked)
>> +             spin_unlock_irqrestore(&port->lock, flags);
>> +}
>
> [1]
>         http://article.gmane.org/gmane.linux.drivers.devicetree/106483
>
> baruch
>
> --
>      http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
> =}------------------------------------------------ooO--U--Ooo------------{=
>    - baruch@...s.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -
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