[U-Boot] [PATCH v2 09/11] S3C24XX: Add NAND Flash driver

[José Miguel Gonçalves]

On 17-09-2012 19:27, Tom Rini wrote:
> On Mon, Sep 17, 2012 at 07:05:48PM +0100, Jos? Miguel Gon?alves wrote:
>> On 17-09-2012 18:56, Tom Rini wrote:
>>> -----BEGIN PGP SIGNED MESSAGE-----
>>> Hash: SHA1
>>>
>>> On 09/17/12 10:08, Jos? Miguel Gon?alves wrote:
>>>> On 17-09-2012 17:57, Tom Rini wrote:
>>>>> On Sun, Sep 16, 2012 at 10:16:47AM +0100, Jos? Miguel Gon?alves
>>>>> wrote:
>>>>>> On 09/14/2012 08:01 PM, Tom Rini wrote:
>>>>>>> On Fri, Sep 14, 2012 at 07:45:40PM +0100, Jos? Miguel
>>>>>>> Gon?alves wrote:
>>>>>>>> On 14-09-2012 19:21, Marek Vasut wrote:
>>>>>>>>> Dear Jos? Miguel Gon?alves,
>>>>>>>>>
>>>>>>>>>> NAND Flash driver with HW ECC for the S3C24XX SoCs.
>>>>>>>>>> Currently it only supports SLC NAND chips.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Jos? Miguel Gon?alves
>>>>>>>>>> <jose.goncalves at inov.pt>
>>>>>>>>> [...]
>>>>>>>>>
>>>>>>>>>> +#include <common.h> +#include <nand.h> +#include
>>>>>>>>>> <asm/io.h> +#include <asm/arch/s3c24xx_cpu.h> +#include
>>>>>>>>>> <asm/errno.h> + +#define MAX_CHIPS    2 +static int
>>>>>>>>>> nand_cs[MAX_CHIPS] = { 0, 1 }; + +#ifdef
>>>>>>>>>> CONFIG_SPL_BUILD +#define printf(arg...) do {} while
>>>>>>>>>> (0)
>>>>>>>>> This doesn't seem quite right ...
>>>>>>>>>
>>>>>>>>> 1) this should be in CPU directory 2) should be enabled
>>>>>>>>> only if CONFIG_SPL_SERIAL_SUPPORT is not set 3) should be
>>>>>>>>> inline function, not a macro
>>>>>>>> 1) and 3) OK. Don't quite understand 2). I want to remove
>>>>>>>> the printfs in the SPL build, as it would blown up the
>>>>>>>> internal SoC RAM space available. So why add a condition
>>>>>>>> with CONFIG_SPL_SERIAL_SUPPORT?
>>>>>>> You've got 8KB, based on the final patch in the series.  At
>>>>>>> least in my SPL series that's still enough to get you
>>>>>>> printf/puts (I believe 4kb was the cutoff where that had to
>>>>>>> be dropped).
>>>>>>>
>>>>>> Barely:
>>>>>>
>>>>>> $ size u-boot-spl text       data        bss        dec
>>>>>> hex    filename 3337          8        588       3933
>>>>>> f5d    u-boot-spl
>>>>>>
>>>>>> $ size u-boot-spl-printf text       data        bss        dec
>>>>>> hex    filename 7968          8        604       8580
>>>>>> 2184 u-boot-spl-printf
>>>>>>
>>>>>> The printf is not so important that justifies exhausting the
>>>>>> IRAM space available and preventing any future SPL
>>>>>> expansion...
>>>>> There's two parts to this: - What else can you do in a single
>>>>> binary, in theory?  Is there boot medium detection and you would
>>>>> want to have, for example, NAND and SD support in the same
>>>>> binary?  I would say memory is meant for using, but this is a
>>>>> board maintainer decision and that's you :)
>>>> That's exactly what I've got in mind when I talked about a future
>>>> expansion! Being able to boot also from an SD card. With only 8KB
>>>> for .text and .data, I can not use printfs in the SPL for this
>>>> platform (at least with the present printf support for SPL).
>>>>
>>>>> - We have a define today (CONFIG_SPL_LIBCOMMON_SUPPORT) that
>>>>> toggles printf or no printf.  If we really need to say yes to
>>>>> LIBCOMMON_SUPPORT and no to printf, we need finer grained config
>>>>> options and then a do-nothing printf is used for SPL.  Doing the
>>>>> opt-out driver by driver just punts this problem down the road to
>>>>> the next developer and that's not very nice (and adding
>>>>> CONFIG_SPL_PRINTF_SUPPORT shouldn't be a big patch, modify a few
>>>>> Makefiles, update a bunch of config files, add
>>>>> common/spl/dummy_funcs.c and a __weak printf).
>>> OK, so please take a stab at option two, on top of my SPL series,
>>> keeping in mind what Scott has said (which makes sense) because
>>> otherwise you'll be changing a lot of MMC files too to drop out printf :)
>> The solution that I sorted out on the current SPL framework was to add this:
>>
>> #ifdef CONFIG_SPL_BUILD
>> #define printf(arg...) do {} while (0)
>> #ifdef CONFIG_SPL_SERIAL_SUPPORT
>> #define puts(arg) serial_puts(arg)
>> #endif
>> #endif
>>
>> on a CPU specific header. Marek told me to not use macros, but to
>> use inline functions instead, but has I told earlier on this thread,
>> I am unable to do that. Suggestions for doing this in a better way
>> are welcome...
> It's gotta go in <common.h>, and something like
> /* Big comment what / why */
> #if !defined(CONFIG_SPL_BUILD) || \
>     (CONFIG_SPL_BUILD && CONFIG_SPL_PRINTF_SUPPORT)
> void putc(...);
> void puts(...);
> int printf(....);
> #else
> #define putc(c) serial_putc(c)
> #define puts(s) serial_puts(s)
> #define printf(arg...) do {} while (0)
> #endif
>

Are macros OK to remove printf() and to replace putc()/puts() by 
serial_putc()/serial_puts() in the SPL?
Shouldn’t we be using inline functions instead?