From mboxrd@z Thu Jan 1 00:00:00 1970 From: Huang Shijie Subject: Re: [PATCH] mtd: gpmi: Remove "We support only one NAND chip" from bindings doc Date: Tue, 2 Dec 2014 08:38:40 +0800 Message-ID: <20141202003840.GA11370@shldeISGChi005.sh.intel.com> References: <1417097929-17832-1-git-send-email-sr@denx.de> <20141128014832.GA3113@localhost.localdomain> <54781DD5.5030801@denx.de> <20141129024047.GA5056@localhost.localdomain> <20141130065326.GB3608@norris-Latitude-E6410> <20141130154255.GB14834@localhost.localdomain> <547C3BB9.1010706@denx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <547C3BB9.1010706-ynQEQJNshbs@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stefan Roese Cc: Huang Shijie , Brian Norris , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, Dec 01, 2014 at 10:58:17AM +0100, Stefan Roese wrote: > On 30.11.2014 16:42, Huang Shijie wrote: > > On Sat, Nov 29, 2014 at 10:53:26PM -0800, Brian Norris wrote: > >> On Sat, Nov 29, 2014 at 10:40:50AM +0800, Huang Shijie wrote: > >>> On Fri, Nov 28, 2014 at 08:01:41AM +0100, Stefan Roese wrote: > >>>> On 28.11.2014 02:48, Huang Shijie wrote: > >>>>> On Thu, Nov 27, 2014 at 03:18:49PM +0100, Stefan Roese wrote: > >>>>>> This sentence "We support only one NAND chip now" is not true any more. > >>>>>> Multiple chips are supported. So lets remove this sentence to not > >>>>> > >>>>> The gpmi can only supports one chip. Of course, there are maybe two dies > >>>>> in this single chip. > >>>> > >>>> Now I'm a bit confused. The i.MX6 supports 4 chips select signals. And isn't > >>>> "two dies in this single chip" not practically the same as connecting 2 (or > >>>> more) chips (same device) to multiple chip selects of the SoC? Where is the > >>>> difference here? > >>> The "one chip" here is means the "one package" (TSOP or BGA ....). > >> > >> Then why is this even in the DT binding doc? Isn't that a board-level > >> constraint (and not a chip property) which should be obvious to the > >> user? If so, then should we just drop the language? Or at a minimum, > >> make it more specific so it doesn't confuse readers. > > > > yes. It is okay to send a patch to make it more clear. > > > >> > >>> (In logic, "two dies in this single chip" is same as connecting 2 chips > >>> to the gpmi.) > >> > >> ...which means that logically, you can connect more than one chip to the > >> GPMI, right? > > The gpmi can only connect with one physical chip now, but there maybe > > two DIEs in this chip. > > I really fail to see why you make this distinction between two chips on a die > and two external chips. For the SoC this should really look identical, right? > > Please explain again, why exactly only two chips on one die are supported. There are only 8 data lines for gpmi. I guess there may bugs in the gpmi driver to support the two external chips in such case: Two different processes access different NAND chips at the same time. I even did not have enough time to test the "two chips on a die" case very carefully before I left freescale. > > BTW: We have a custom i.MX6DL based board with 2 NAND chips connected. And Very good. Please test this board with the UBIFS in the multi processes case. (I ever used the bonnie++) > Linux seems to support both chips just fine. Here the boot log: > > [ 1.085812] nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xdc > [ 1.092218] nand: Micron MT29F4G08ABADAH4 > [ 1.096245] nand: 512MiB, SLC, page size: 2048, OOB size: 64 > [ 1.102171] nand: 2 chips detected > [ 1.106156] gpmi-nand 112000.gpmi-nand: enable the asynchronous EDO mode 5 > [ 1.113094] Scanning device for bad blocks could you please post more log? thanks Huang Shijie > > Comments welcome... > > Thanks, > Stefan > > > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/ -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html