Re: [PATCH] mtd: atmel_nand: fix the warning when CONFIG_OF is not defined

[Josh Wu <josh.wu@atmel.com>]

Hi, Ezequiel

On 9/3/2013 1:13 AM, Ezequiel Garcia wrote:
> On Mon, Sep 02, 2013 at 03:02:00PM +0800, Josh Wu wrote:
>> Hi, Ezequiel
>>
>> On 9/1/2013 1:04 AM, Ezequiel Garcia wrote:
>>> On Fri, Aug 30, 2013 at 09:23:53PM +0100, David Woodhouse wrote:
>>>> On Wed, 2013-08-07 at 11:36 +0800, Josh Wu wrote:
>>>>> This patch fix following warning:
>>>>>
>>>>> drivers/mtd/nand/atmel_nand.c:2007: warning: 'atmel_nand_nfc_match' defined but not used
>>>>>
>>>>> This patch add '#if defined(CONFIG_OF)' block to guard around the definition of
>>>>> atmel_nand_nfc_match, in order to avoid the warning when kernel is configurated
>>>>> as non-dt supported.
>>>> Ick. This driver is littered with CONFIG_OF checks. Yet I've just seen a
>>>> patch to pxa3xx_nand which *removes* ifdefs, on the basis that all the
>>>> of_match_ functions/macros will just 'do the right thing'. Can't we do
>>>> that here too? We might just need to add __maybe_unused?
>>>>
>>> We can. We just need to provide a few dummy functions in linux/of_mtd.h
>>> just like the other of_xxx() are doing. See below!
>>>
>>>>> +#if defined(CONFIG_OF)
>>>>>    static struct of_device_id atmel_nand_nfc_match[] = {
>>>>>    	{ .compatible = "atmel,sama5d3-nfc" },
>>>>>    	{ /* sentinel */ }
>>>>>    };
>>>>> +#endif
>>>> Also, why doesn't this one appear in a MODULE_DEVICE_TABLE() ?
>>>>
>>> Indeed. And why doesn't it have a "const" keyword?
>> Thanks to point these out.
>>
>>> So, in order to remove the CONFIG_OF safely from this driver,
>>> and avoid any stupid warnings, we need to first implement
>>> these dummies:
>>>
>>> --------------------------------8<-----------------------------------
>>> diff --git a/include/linux/of_mtd.h b/include/linux/of_mtd.h
>>> index ed7f267..66f173e 100644
>>> --- a/include/linux/of_mtd.h
>>> +++ b/include/linux/of_mtd.h
>>> @@ -14,6 +14,21 @@
>>>    int of_get_nand_ecc_mode(struct device_node *np);
>>>    int of_get_nand_bus_width(struct device_node *np);
>>>    bool of_get_nand_on_flash_bbt(struct device_node *np);
>>> +#else
>>> +static inline int of_get_nand_ecc_mode(struct device_node *np)
>>> +{
>>> +	return -ENOSYS;
>>> +}
>>> +
>>> +static inline int of_get_nand_bus_width(struct device_node *np)
>>> +{
>>> +	return -ENOSYS;
>>> +}
>>> +
>>> +static inline bool of_get_nand_on_flash_bbt(struct device_node *np)
>>> +{
>>> +	return false;
>>> +}
>>>    #endif
>>>    
>>>    #endif /* __LINUX_OF_MTD_H */
>>> -------------------------------->8-----------------------------------
>>>
>>> And then, with this little patch, we get rid of the ugly CONFIG_OF check
>>> from the atmel_nand driver:
>>>
>>> --------------------------------8<-----------------------------------
>>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
>>> index 0e365da..ac58098 100644
>>> --- a/drivers/mtd/nand/atmel_nand.c
>>> +++ b/drivers/mtd/nand/atmel_nand.c
>>> @@ -1448,7 +1448,6 @@ static void atmel_nand_hwctl(struct mtd_info *mtd, int mode)
>>>    		ecc_writel(host->ecc, CR, ATMEL_ECC_RST);
>>>    }
>>>    
>>> -#if defined(CONFIG_OF)
>>>    static int atmel_of_init_port(struct atmel_nand_host *host,
>>>    			      struct device_node *np)
>>>    {
>>> @@ -1456,7 +1455,7 @@ static int atmel_of_init_port(struct atmel_nand_host *host,
>>>    	u32 offset[2];
>>>    	int ecc_mode;
>>>    	struct atmel_nand_data *board = &host->board;
>>> -	enum of_gpio_flags flags;
>>> +	enum of_gpio_flags flags = 0;
>>>    
>>>    	if (of_property_read_u32(np, "atmel,nand-addr-offset", &val) == 0) {
>>>    		if (val >= 32) {
>>> @@ -1539,13 +1538,6 @@ static int atmel_of_init_port(struct atmel_nand_host *host,
>>>    
>>>    	return 0;
>>>    }
>>> -#else
>>> -static int atmel_of_init_port(struct atmel_nand_host *host,
>>> -			      struct device_node *np)
>>> -{
>>> -	return -EINVAL;
>>> -}
>>> -#endif
>>>    
>>>    static int __init atmel_hw_nand_init_params(struct platform_device *pdev,
>>>    					 struct atmel_nand_host *host)
>>> @@ -2205,14 +2197,12 @@ static int __exit atmel_nand_remove(struct platform_device *pdev)
>>>    	return 0;
>>>    }
>>>    
>>> -#if defined(CONFIG_OF)
>>>    static const struct of_device_id atmel_nand_dt_ids[] = {
>>>    	{ .compatible = "atmel,at91rm9200-nand" },
>>>    	{ /* sentinel */ }
>>>    };
>>>    
>>>    MODULE_DEVICE_TABLE(of, atmel_nand_dt_ids);
>>> -#endif
>>>    
>>>    static int atmel_nand_nfc_probe(struct platform_device *pdev)
>>>    {
>>> @@ -2251,12 +2241,11 @@ static int atmel_nand_nfc_probe(struct platform_device *pdev)
>>>    	return 0;
>>>    }
>>>    
>>> -#if defined(CONFIG_OF)
>>> -static struct of_device_id atmel_nand_nfc_match[] = {
>>> +static const struct of_device_id atmel_nand_nfc_match[] = {
>>>    	{ .compatible = "atmel,sama5d3-nfc" },
>>>    	{ /* sentinel */ }
>>>    };
>>> -#endif
>>> +MODULE_DEVICE_TABLE(of, atmel_nand_nfc_match);
>>>    
>>>    static struct platform_driver atmel_nand_nfc_driver = {
>>>    	.driver = {
>>> -------------------------------->8-----------------------------------
>>>
>>> Of course, these are untested. If they look OK and don't cause any trouble,
>>> then I'll prepare proper patches.
>> Looks nice to me. Your proposal patch does the right thing to remove the
>> CONFIG_OF.
> Great!
>
>> So please sent them out. ;)
>>
> I'm a bit short on time these days, how about I send the first one
> for the stub !OF addition and on top of that you send the atmel
> patches?

Okay.

Best Regards,
Josh Wu