From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wi0-f170.google.com ([209.85.212.170]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Z4nR3-0005jM-AA for linux-mtd@lists.infradead.org; Tue, 16 Jun 2015 09:45:38 +0000 Received: by wiga1 with SMTP id a1so103339483wig.0 for ; Tue, 16 Jun 2015 02:45:12 -0700 (PDT) MIME-Version: 1.0 From: Roy Spliet To: Linux MTD Mailinglist , David Woodhouse , Brian Norris , Maxime Ripard , Boris Brezillon , Baruch Siach , Rafal Milecki Subject: [RFC] Support custom timings for NAND chips Date: Tue, 16 Jun 2015 11:45:01 +0200 Message-Id: <1434447904-31748-1-git-send-email-r.spliet@ultimaker.com> Content-Type: text/plain; charset=US-ASCII List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello, Following is a fairly simple set of three patches that both implement and demonstrate the use of custom timings for chip. This follows from the requirement to support the Hynix H27UBG8T2BTR-BC, as shipped by Olimex on their Allwinner-based ARM-boards. I motivate my chosen approach as follows: 1) Requirement. The NAND chip is being used in the wild, and using the only supported ONFI timing (0) is significantly degrading performance. 2) Simplicity. The three patches are fairly straightforward, and do what they should do without compromise. Alternative approaches like sticking timings in the DT makes it more difficult for distribution to ship universal kernels and DTBs, because it's a NAND chip property and not a board property. I send this out now (asap), because the only legacy that requires a change is sunxi-nand. The longer we wait, the harder it gets. Don't let that stop you from doing a proper review job! :-) Comments? Ideas? Yours, Roy -- IMAGINE IT >> MAKE IT Meet us online at Twitter , Facebook , Google+ www.ultimaker.com