Hi Peter,

On Thursday 29 January 2015 09:19 PM, Peter Hurley wrote:
> Hi Varka,
>
> On 01/29/2015 10:26 AM, Varka Bhadram wrote:
>> Hi,
>>
>> On Wednesday 28 January 2015 04:38 PM, Chunyan Zhang wrote:
>>> Add a full sc9836-uart driver for SC9836 SoC which is based on the
>>> spreadtrum sharkl64 platform.
>>> This driver also support earlycon.
>>>
>>> Originally-by: Lanqing Liu <lanqing.liu@spreadtrum.com>
>>> Signed-off-by: Orson Zhai <orson.zhai@spreadtrum.com>
>>> Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
>>> Acked-by: Arnd Bergmann <arnd@arndb.de>
>>> Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
>>> ---
>>>    drivers/tty/serial/Kconfig       |   18 +
>>>    drivers/tty/serial/Makefile      |    1 +
>>>    drivers/tty/serial/sprd_serial.c |  793 ++++++++++++++++++++++++++++++++++++++
>>>    include/uapi/linux/serial_core.h |    3 +
>>>    4 files changed, 815 insertions(+)
>>>    create mode 100644 drivers/tty/serial/sprd_serial.c
>>>
>> (...)
>>
>>> +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 = UPF_BOOT_AUTOCONF;
>>> +
>>> +    clk = devm_clk_get(&pdev->dev, NULL);
>>> +    if (!IS_ERR(clk))
>>> +        up->uartclk = clk_get_rate(clk);
>>> +
>>> +    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> +    if (!res) {
>>> +        dev_err(&pdev->dev, "not provide mem resource\n");
>>> +        return -ENODEV;
>>> +    }
>> This check is not required. It will be done by devm_ioremap_resource()
> I disagree. devm_ioremap_resource() interprets the NULL resource as
> a bad parameter and returns -EINVAL which is then forwarded as the
> return value from the probe.
>
> -ENODEV is the correct return value from the probe if the expected
> resource is not available (either because it doesn't exist or was already
> claimed by another driver).

Check on the resource happening with evm_ioremap_resource.

Not necessary to check multiple times.

I did series for all the drivers. see [1]

[1]:  https://lkml.org/lkml/2014/11/3/986  <https://lkml.org/lkml/2014/11/3/986>

> Regards,
> Peter Hurley
>
>>> +    up->mapbase = res->start;
>>> +    up->membase = devm_ioremap_resource(&pdev->dev, res);
>>> +    if (IS_ERR(up->membase))
>>> +        return PTR_ERR(up->membase);
>>> +
>>>

-- 
Thanks,
Varka Bhadram.