From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from am1ehsobe004.messaging.microsoft.com ([213.199.154.207] helo=am1outboundpool.messaging.microsoft.com) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VOl3V-0001Rz-FA for linux-mtd@lists.infradead.org; Wed, 25 Sep 2013 09:06:46 +0000 Message-ID: <5242A805.50804@freescale.com> Date: Wed, 25 Sep 2013 17:08:21 +0800 From: Huang Shijie MIME-Version: 1.0 To: Marek Vasut Subject: Re: gpmi-nand driver and jffs2 support References: <522062B4.4080709@digi.com> <201309241150.09313.marex@denx.de> <52416D88.6030906@freescale.com> <201309241453.47069.marex@denx.de> In-Reply-To: <201309241453.47069.marex@denx.de> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: quoted-printable Cc: "fabio.estevam@freescale.com" , Hector Palacios , linux-mtd@lists.infradead.org, dzu@denx.de List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , =E4=BA=8E 2013=E5=B9=B409=E6=9C=8824=E6=97=A5 20:53, Marek Vasut =E5=86=99= =E9=81=93: > Hello Huang, > >> =E4=BA=8E 2013=E5=B9=B409=E6=9C=8824=E6=97=A5 17:50, Marek Vasut =E5=86= =99=E9=81=93: >>> Hello Huang, >>> >>> Can you please explain what is the exact difference between the NAND >>> layout when using JFFS2 in FSL 2.6.35 and in mainline with your patch= es >>> ? >> In FSL 2.6.35, there are some free space in the OOB; >> while in mainline we use all the free space in the OOB. > OK, let me understand this in more detail. > > How does the NAND page look when written by FSL 2.6.35 and how does the= NAND > page look when written by current mainline ? Can you please tell in det= ail? > [1] for FSL 2.6.35, see gpmi_nfc_set_geometry(): The ecc_strength is set at a fix value, such as: "set ecc_strength with 8 for page size 2048"; Why set the ecc_strength with 8? just based on the experiences, not=20 based on the chip's datasheets. So we can have some spare space in the OOB, after we setting the=20 BCH with the ecc_strength. [2] for mainline, see common_nfc_set_geometry(): Please see the diagrams in the set_geometry_by_ecc_info() and=20 legacy_set_geometry(). If we CAN use the ecc info from the chip's datasheet, just like in=20 FSL_2.6.35, we may have some spare space in the OOB; else we use all the OOB. >>> Is there any way to mount JFFS2 written with FSL 2.6.35 on current >>> mainline? Thus far, neither me nor Hector were able to mount such >>> partition with the same result. >> The gpmi driver in FSL 2.6.35 is different from the mainline. > I was under the impression the mainline driver is an evolution of the F= SL 2.6.35 > driver. Is this assumption incorrect? > yes. >> The two drivers are not compatible to each other. > OK, like I said, if we cannot produce a drop-in replacement of old FSL = 2.6.35 > kernel, this is a problem. People will come and they will be running in= to this > issue. Thus, let us focus on producing a compatible JFFS2 patch. I do not think it is a problem. The FSL 2.6.35 does not support the JFFS2= . thanks Huang Shijie