From mboxrd@z Thu Jan  1 00:00:00 1970
From: Lukasz Majewski <l.majewski@samsung.com>
Date: Mon, 31 Mar 2014 11:49:56 +0200
Subject: [U-Boot] [PATCH 3/3] dfu: Introduction of the
 "dfu_checksum_method" env variable for checksum method setting
In-Reply-To: <201403311129.17258.marex@denx.de>
References: <1396255729-6573-1-git-send-email-l.majewski@samsung.com>
	<201403311104.13887.marex@denx.de> <20140331112431.1157e1c8@amdc2363>
	<201403311129.17258.marex@denx.de>
Message-ID: <20140331114956.528dd0a3@amdc2363>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

Hi Marek,

> On Monday, March 31, 2014 at 11:24:31 AM, Lukasz Majewski wrote:
> > Hi Marek,
> > 
> > > On Monday, March 31, 2014 at 10:48:49 AM, Lukasz Majewski wrote:
> > > > Up till now the CRC32 of received data was calculated
> > > > unconditionally. The standard crc32 implementation causes long
> > > > delays when large images were uploaded.
> > > 
> > > You might want to check common/cmd_hash.c and include/hash.h for
> > > the hash_command() call. It does the resolution of the hash
> > > algorithm from it's name and you can operate also SHA1 and SHA256
> > > with it. It would be nice if you could just extend it a bit and
> > > use that instead of adding another ad-hoc mechanism.
> > > 
> > > Do you think it'd be possible to reuse it please ?
> > 
> > I think, that crc32 shall be calculated when needed. That is why
> > I've added a dfu_ckecksum_method variable.
> > 
> > With its help it is now possible to use different algorithms for
> > checking - not only crc32 (which in u-boot is the default and
> > painfully slow implementation).
> > 
> > In the future the code:
> > if (dfu_checksum_method == DFU_CRC32)
> > 	crc32 calculation;
> > 
> > will be changed to:
> > 
> > switch (dfu_checksum_method) {
> > 	case CRC32:
> > 		crc32 calculation;
> > 		break;
> > 	case SHA1:
> > 		sha1 calculation;
> > 		break;
> > 	case MD5:
> > 		md5 calculation;
> > 		break;
> > }
> > 
> > Moreover it is possible to dynamically change the checksum method
> > (between invoking dfu command) via adjusting "dfu_checksum_method"
> > variable.
> > 
> > The default approach is to not calculate anything.
> 
> I get it, but the direct calling of crc32() function can be
> abstracted already with the hash_command() now. You won't need to the
> above switch in such case. Also, you can implement a NULL hash algo,
> which would effectivelly model the case where you want to disable
> hashing.

I will look closer to the hash_command() - maybe it would be enough to
only call it with a proper parameter.

Thanks for tip.

> 
> Best regards,
> Marek Vasut


-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group