From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailhost.rdmcorp.com ([204.225.180.10]) by pentafluge.infradead.org with esmtp (Exim 3.22 #1 (Red Hat Linux)) id 17sQ1D-0007sb-00 for ; Fri, 20 Sep 2002 16:48:36 +0100 Received: from PARKER (10.1.2.1) by mailhost.rdmcorp.com (Worldmail 1.3.167) for linux-mtd@lists.infradead.org; 20 Sep 2002 11:53:14 -0400 From: "Jack Lu" To: Subject: about jffs2's compression and cfi->fast_prog being turn off Date: Mon, 20 May 2002 11:47:52 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-mtd-admin@lists.infradead.org Errors-To: linux-mtd-admin@lists.infradead.org List-Help: List-Post: List-Subscribe: , List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: Hi I read the paper posted on May5th 2001 by Vinip Malik, it says: One down side to this is that if you are writing compressed data to the system, the CPU will spend time trying to compress it further. At this time of writing, compression cannot be turned off. There are some plans to implement this feature however (even turn it off on a directory by directory basis!). Now I have set up the jffs2 file system using the latest source code downloadded from website. 1. With this latest jffs2, can we turn off the compression? If can , how can we turn it? By the way, our compression algorithm is the CCITT Group 4 compression of bi-level image, the image written to a file with TIFF6.0 file format. 2. If we still use the jffs2 compression after we compress the image using CCITT4 Group algorithm, could it help us to reduce the size to store the compressed image into the flash memory? 3. With the latest jffs2, the erase suspend is implemented for AMD CFI chips, such as Am29Lv320MB? 4. The cfi_cmdset_0002.c file includes: if (cfi->fast_prog) { /* In cfi_amdstd_write() we frob the protection stuff without paying any attention to the state machine. This upsets in-progress erases. So we turn this flag off for now till the code gets fixed. */ printk(KERN_NOTICE "cfi_cmdset_0002: Disabling fast programming due to code brokenness.\n"); cfi->fast_prog = 0; } Turnning off the cfi->fast_prog will affect the the time needed to program the flahsh? Thanks.