Re: [PATCH 3/8] arm/cpu/start.c: Distil some common code in __start().

[Sascha Hauer <s.hauer@pengutronix.de>]

On Sun, Oct 11, 2015 at 11:43:36AM -0700, Andrey Smirnov wrote:
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>  arch/arm/cpu/start.c | 49 +++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 35 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
> index 8e5097b..7ffde7c 100644
> --- a/arch/arm/cpu/start.c
> +++ b/arch/arm/cpu/start.c
> @@ -53,6 +53,18 @@ void *barebox_arm_boot_dtb(void)
>  	return barebox_boot_dtb;
>  }
>  
> +static uint32_t get_any_boarddata_magic(const void *boarddata)
> +{
> +	if (get_unaligned_be32(boarddata) == FDT_MAGIC)
> +		return FDT_MAGIC;
> +
> +	if (((struct barebox_arm_boarddata *)boarddata)->magic ==
> +	    BAREBOX_ARM_BOARDDATA_MAGIC)
> +		return BAREBOX_ARM_BOARDDATA_MAGIC;
> +
> +	return 0;
> +}
> +
>  static noinline __noreturn void __start(unsigned long membase,
>  		unsigned long memsize, void *boarddata)
>  {
> @@ -89,21 +101,30 @@ static noinline __noreturn void __start(unsigned long membase,
>  	}
>  
>  	if (boarddata) {
> -		if (get_unaligned_be32(boarddata) == FDT_MAGIC) {
> -			uint32_t totalsize = get_unaligned_be32(boarddata + 4);
> +		uint32_t totalsize;
> +		void **var = NULL;
> +		const char *name;
> +
> +		switch (get_any_boarddata_magic(boarddata)) {
> +		case FDT_MAGIC:
> +			totalsize = get_unaligned_be32(boarddata + 4);
> +			var = &barebox_boot_dtb;
> +			name = "DTB";
> +			break;
> +		case BAREBOX_ARM_BOARDDATA_MAGIC:
> +			totalsize = sizeof(struct barebox_arm_boarddata);
> +			var = &barebox_boarddata;
> +			name = "machine type";
> +			break;
> +		default:
> +			break;
> +		}
> +
> +		if (var) {
>  			endmem -= ALIGN(totalsize, 64);
> -			barebox_boot_dtb = (void *)endmem;
> -			pr_debug("found DTB in boarddata, copying to 0x%p\n",
> -					barebox_boot_dtb);
> -			memcpy(barebox_boot_dtb, boarddata, totalsize);
> -		} else if (((struct barebox_arm_boarddata *)boarddata)->magic ==
> -				BAREBOX_ARM_BOARDDATA_MAGIC) {
> -			endmem -= ALIGN(sizeof(struct barebox_arm_boarddata), 64);
> -			barebox_boarddata = (void *)endmem;
> -			pr_debug("found machine type in boarddata, copying to 0x%p\n",
> -					barebox_boarddata);
> -			memcpy(barebox_boarddata, boarddata,
> -					sizeof(struct barebox_arm_boarddata));
> +			pr_debug("found %s in boarddata, copying to 0x%lu\n",
> +				 name, endmem);
> +			*var = memcpy((void *)endmem, boarddata, totalsize);

I do not see a real improvement in this patch. The previously duplicated
code which is now shared is limited to the pr_debug message and the call
to memcpy. This is done at the cost of making the code slightly more
complicated due to the additional void **var indirection. Dropped this
patch for now. Maybe some additional cleanup or feature may make this
patch more useful, in that case I'll take it then later.

Sascha

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