Re: [PATCH 1/2] mtd: atmel_nand: remove unneeded ifdef CONFIG_OF

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

Dear Brian

On 9/12/2013 7:02 AM, Brian Norris wrote:
> Hi Josh,
>
> On Tue, Sep 03, 2013 at 05:20:27PM +0800, Josh Wu wrote:
>> Since following commit
>>    f3b391425d21e6138e57b2432d91134e0bc2b975
> This commit ID will likely change before it gets merged, since there may
> be rebasing, and David usually adds his signoff. David or I can take
> care of that later though.

OK. I think I need to remove the commit ID part.

>
>>    (of_mtd: Add no-op stubs to support CONFIG_OF=n)
>>
>> implements the stub for CONFIG_OF=n. Now we can safely remove all
>> CONFIG_OF in atmel_nand. (Thanks to Ezequiel Garcia's for this protype)
> I'm not quite so sure about this patch, as I was about the pxa3xx patch.
> With pxa3xx, the compiler can easily tell that pxa3xx_nand_probe_dt()
> will return 0 without doing anything in the !CONFIG_OF case (and so will
> likely remove the dead code), so it's no benefit to have the #ifdef. But
> in this driver, the atmel_of_init_port() function can't be trivially
> determined to do nothing (and in fact, it does something in either
> CONFIG_OF=y or =n case). It's only protected by the 'if
> (pdev->dev.of_node)' check, which the compiler can't predict.

I understand your concern here.

>
> So, I don't know if we should remove the #ifdef at the expense of likely
> significantly larger code. I won't protest, but I won't merge it yet
> either. Perhaps others have better ideas, or perhaps you can find a good
> way to work around this -- e.g., check the of_* helpers for -ENOSYS early
> in atmel_of_init_port()?

So what about to add one more check： "IS_ENABLE(CONFIG_OF)" in 
atmel_nand_probe().
And which is compiler predictable.

if (IS_ENABLED(CONFIG_OF) && pdev->dev.of_node) {
/* of_node can be parsed only when CONFIG_OF is enable */
res = atmel_of_init_port(host, pdev->dev.of_node);
if (res)
goto err_nand_ioremap;
} else {
... ...
}

And thanks for the comments.
Best Regards,
Josh Wu

>
>> Signed-off-by: Josh Wu <josh.wu@atmel.com>
>> ---
>>   drivers/mtd/nand/atmel_nand.c |   14 +-------------
>>   1 file changed, 1 insertion(+), 13 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
>> index 060feea..1ca0724 100644
>> --- a/drivers/mtd/nand/atmel_nand.c
>> +++ b/drivers/mtd/nand/atmel_nand.c
>> @@ -1449,7 +1449,6 @@ 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)
>>   {
>> @@ -1457,7 +1456,7 @@ 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) {
>> @@ -1540,13 +1539,6 @@ 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)
>> @@ -2207,14 +2199,12 @@ 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)
>>   {
>> @@ -2253,12 +2243,10 @@ 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[] = {
>>   	{ .compatible = "atmel,sama5d3-nfc" },
>>   	{ /* sentinel */ }
>>   };
>> -#endif
>>   
>>   static struct platform_driver atmel_nand_nfc_driver = {
>>   	.driver = {
> Brian