From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bear.ext.ti.com ([192.94.94.41]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wzlo3-00037s-NT for linux-mtd@lists.infradead.org; Wed, 25 Jun 2014 11:56:04 +0000 From: "Gupta, Pekon" To: David Jander Subject: RE: [FRC] [PATCH] MTD: nand_base.c: Enable support for Samsung E-die SLC NAND Date: Wed, 25 Jun 2014 11:55:26 +0000 Message-ID: <20980858CB6D3A4BAE95CA194937D5E73EAF7689@DBDE04.ent.ti.com> References: <1403259137-22171-1-git-send-email-david@protonic.nl> <20980858CB6D3A4BAE95CA194937D5E73EAF6A08@DBDE04.ent.ti.com> <20980858CB6D3A4BAE95CA194937D5E73EAF7560@DBDE04.ent.ti.com> <20140625133129.060cd535@archvile> In-Reply-To: <20140625133129.060cd535@archvile> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "linux-mtd@lists.infradead.org" , Ted Juan , "sjhill@realitydiluted.com" , "tglx@linutronix.de" , Brian Norris , David Woodhouse List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi David, >From: David Jander [mailto:david.jander@protonic.nl] >>"Gupta, Pekon" wrote: >> >From: Ted Juan [mailto:ted.juan@gmail.com] >> >Dear Pekon, >> > >> >I backup the raw data to data2[] before doing elm_decode_bch_error_page= (); >> >Dump code is as below. The raw data is the same with the correction >> >data that all more than 8 bit-flips. >> > >> (a) In that case you should contact the Flash vendor here. >> Fresh NAND device from factory should not violate the spec. >> I don't suspect a driver issue here, because the raw data read itself >> has random bit-flips. > >Sorry to interrupt, but this does sound serious. Are you absolutely sure y= our >hardware is OK? Is the power-supply clean and well enough decoupled? Timin= gs >within specs? If electrical specifications are not met, this could explain= the bit-flips. > I don't have the hardware (board), I'm just helping Ted as I'm actively involved with OMAP NAND drivers from TI side. Ted is the original developer working on this board. However, I don't suspect this to be board supply or noise issue because: (1) A timing mis-match would cause read-failure for whole word, not just few bits in the word. (2) Also, power-supply noise would not cause bit-flips in erased-page, Because erase operation inside flash is usually driver by charged-pumps so a dynamic supply noise may not cause random bit-flips. Though it can can erase-failures, which will be detected on reading STATUS register. > It is possible that Samsung is at fault here (they screwed up the specs f= or this >version anyway), but double checking the hardware looks like a good idea >here... > Agree. But hardware issue will be difficult to identify and debug. Ted, Plz relax timing by 10-20% and check if that makes a difference. with regards, pekon