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Date: Fri, 23 Jan 2015 21:32:43 +0800
From: Lyra Zhang <zhang.lyra@...il.com>
To: Peter Hurley <peter@...leysoftware.com>
Cc: Chunyan Zhang <chunyan.zhang@...eadtrum.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Arnd Bergmann <arnd@...db.de>,
"gnomes@...rguk.ukuu.org.uk" <gnomes@...rguk.ukuu.org.uk>,
Shawn Guo <shawn.guo@...aro.org>,
Pawel Moll <pawel.moll@....com>,
"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
"jslaby@...e.cz" <jslaby@...e.cz>,
Grant Likely <grant.likely@...aro.org>,
Heiko Stübner <heiko@...ech.de>,
"jason@...edaemon.net" <jason@...edaemon.net>,
"florian.vaussard@...l.ch" <florian.vaussard@...l.ch>,
"andrew@...n.ch" <andrew@...n.ch>,
Hayato Suzuki <hytszk@...il.com>,
"antonynpavlov@...il.com" <antonynpavlov@...il.com>,
Orson Zhai <orsonzhai@...il.com>,
"geng.ren@...eadtrum.com" <geng.ren@...eadtrum.com>,
"zhizhou.zhang" <zhizhou.zhang@...eadtrum.com>,
"lanqing.liu@...eadtrum.com" <lanqing.liu@...eadtrum.com>,
Wei Qiao (乔伟) <wei.qiao@...eadtrum.com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
"linux-api@...r.kernel.org" <linux-api@...r.kernel.org>
Subject: Re: [PATCH v6 2/2] tty/serial: Add Spreadtrum sc9836-uart driver support
On Fri, Jan 23, 2015 at 9:12 PM, Peter Hurley <peter@...leysoftware.com> wrote:
> On 01/23/2015 02:23 AM, Lyra Zhang wrote:
>> Hi, Peter
>>
>> Many thanks to you for reviewing so carefully and giving us so many
>> suggestions and so clear explanations.
>
> :)
>
>> I'll address all of your comments and send an updated patch soon.
>>
>> On Fri, Jan 23, 2015 at 11:57 AM, Peter Hurley <peter@...leysoftware.com> wrote:
>
> [...]
>
>>>> +static void sprd_set_termios(struct uart_port *port,
>>>> + struct ktermios *termios,
>>>> + struct ktermios *old)
>>>> +{
>>>> + unsigned int baud, quot;
>>>> + unsigned int lcr, fc;
>>>> + unsigned long flags;
>>>> +
>>>> + /* ask the core to calculate the divisor for us */
>>>> + baud = uart_get_baud_rate(port, termios, old, 1200, 3000000);
>>> ^^^^ ^^^^^^
>>> mabye derive these from uartclk?
>>
>> I'm afraid I can't understand very clearly, Could you explain more
>> details please?
>
> Is the fixed clock divider == 8 and the uartclk == 26000000 ?
> If so,
> baud = uartclk / 8 = 3250000
>
> I see now this is clamping baud inside the maximum, so this is fine.
> Please disregard my comment.
>
> [...]
>
>
>>>> +static int sprd_probe(struct platform_device *pdev)
>>>> +{
>>>> + struct resource *res;
>>>> + struct uart_port *up;
>>>> + struct clk *clk;
>>>> + int irq;
>>>> + int index;
>>>> + int ret;
>>>> +
>>>> + for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
>>>> + if (sprd_port[index] == NULL)
>>>> + break;
>>>> +
>>>> + if (index == ARRAY_SIZE(sprd_port))
>>>> + return -EBUSY;
>>>> +
>>>> + index = sprd_probe_dt_alias(index, &pdev->dev);
>>>> +
>>>> + sprd_port[index] = devm_kzalloc(&pdev->dev,
>>>> + sizeof(*sprd_port[index]), GFP_KERNEL);
>>>> + if (!sprd_port[index])
>>>> + return -ENOMEM;
>>>> +
>>>> + up = &sprd_port[index]->port;
>>>> + up->dev = &pdev->dev;
>>>> + up->line = index;
>>>> + up->type = PORT_SPRD;
>>>> + up->iotype = SERIAL_IO_PORT;
>>>> + up->uartclk = SPRD_DEF_RATE;
>>>> + up->fifosize = SPRD_FIFO_SIZE;
>>>> + up->ops = &serial_sprd_ops;
>>>> + up->flags = ASYNC_BOOT_AUTOCONF;
>>> ^^^^^^^^^
>>> UPF_BOOT_AUTOCONF
>>>
>>> sparse will catch errors like this. See Documentation/sparse.txt
>>
>> you mean we should use UPF_BOOT_AUTOCONF, right?
>
> Yes. Only UPF_* flag definitions should be used with the uart_port.flags
> field.
>
> My comment regarding the sparse tool and documentation is because the
> flags field and UPF_* definitions use a type mechanism to generate
> warnings using the sparse tool if regular integer values are used
> with the flags field.
>
> The type mechanism was specifically introduced to catch using ASYNC_*
> definitions with the uart_port.flags field.
>
> [...]
>
>>>> +static int sprd_suspend(struct device *dev)
>>>> +{
>>>> + int id = to_platform_device(dev)->id;
>>>> + struct uart_port *port = &sprd_port[id]->port;
>>>
>>> I'm a little confused regarding the port indexing;
>>> is platform_device->id == line ? Where did that happen?
>>>
>>
>> Oh, I'll change to assign platform_device->id with port->line in probe()
>
> I apologize; I should have made my comment clearer.
>
> The ->id should not be assigned.
>
> Replace
>
> int id = to_platform_device(dev)->id;
> struct uart_port *port = &sprd_port[id]->port;
>
> uart_suspend_port(&sprd_uart_driver, port);
>
> with
>
> struct sprd_uart_port *sup = dev_get_drvdata(dev);
>
> uart_suspend_port(&sprd_uart_driver, &sup->port);
>
>
> I know it's not obvious but platform_get/set_drvdata() is really
> dev_get/set_drvdata() using the embedded struct device dev.
>
I've just sent the v7 before I saw your this email, but I'll address
this point in the next version.
Thanks a lot,
Chunyan
>>
>>>
>>>> +
>>>> + uart_suspend_port(&sprd_uart_driver, port);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int sprd_resume(struct device *dev)
>>>> +{
>>>> + int id = to_platform_device(dev)->id;
>>>> + struct uart_port *port = &sprd_port[id]->port;
>>>> +
>>>> + uart_resume_port(&sprd_uart_driver, port);
>
> same here
>
>>>> + return 0;
>
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