linux-kernel - Re: [PATCH v2] mmc : general purpose partition support.

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Date:	Wed, 28 Sep 2011 09:08:07 -0700 (PDT)
From:	Andrei Warkentin <awarkentin@...are.com>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	adrian hunter <adrian.hunter@...el.com>,
	james p freyensee <james_p_freyensee@...ux.intel.com>,
	cjb@...top.org, linux-mmc@...r.kernel.org
Subject: Re: [PATCH v2] mmc : general purpose partition support.

Hi Namjae,

In general I think your approach is fine and solves the problem. See further inline
comments.

----- Original Message -----
> From: "Namjae Jeon" <linkinjeon@...il.com>
> To: cjb@...top.org, linux-mmc@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org, awarkentin@...are.com, "adrian hunter" <adrian.hunter@...el.com>, "james p
> freyensee" <james_p_freyensee@...ux.intel.com>, "Namjae Jeon" <linkinjeon@...il.com>
> Sent: Saturday, September 24, 2011 1:07:00 AM
> Subject: [PATCH v2] mmc : general purpose partition support.
> 
> It allows gerneral purpose partitions in MMC Device.
> And I try to simpliy make mmc_blk_alloc_parts using mmc_part
> structure suggested by Andrei Warkentin.
> After patching, we can see general purpose partitions like this.
> > cat /proc/partitions
>           179 0 847872 mmcblk0
>           179 192 4096 mmcblk0gp4
>           179 160 4096 mmcblk0gp3
>           179 128 4096 mmcblk0gp2
>           179 96  1052672 mmcblk0gp1
>           179 64  1024 mmcblk0boot1
>           179 32  1024 mmcblk0boot0
> 
> Signed-off-by: Namjae Jeon <linkinjeon@...il.com>

> +		if (ext_csd[EXT_CSD_BOOT_MULT]) {
> +			for (i = 0, boot_part_config = 0x1;
> +				i < MMC_NUM_BOOT_PARTITION;
> +				i++, boot_part_config++) {
> +				card->part[i].size = ...
> +				card->part[i].cookie = ...
> +				sprintf(card->part[i].name, "boot%d", i);
> +				card->part[i].force_ro = ...
> +			}
> +		}
>  	}
>  
>
> +		if (ext_csd[EXT_CSD_PARTITION_SUPPORT] & 0x1) {
> +                     ....
> +			int i, gp_num, gp_part_config, gp_size_mult;
> +			for (i = 2, gp_num = 1, gp_part_config = 0x4,
> +				card->part[i].size = ...
> +				card->part[i].cookie = ...
> +				sprintf(card->part[i].name,
> +					"gp%d", gp_num);
> +				card->part[i].force_ro = ..
> +			}
> +		}
>

I feel that you should factor out a function that operates on the static part[] array and
adds a new entry base name, index (i.e. the %d for gp%d), cookie, size, force. 
Otherwise you end up with these hidden mines like fixed indeces for
particular parts (i = 2, etc...) which becomes indecipherable for others. 
Plus you're mostly doing the same thing.

Thanks,
A
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