> -----Original Message----- > From: Brian Norris [mailto:computersforpeace@xxxxxxxxx] > Sent: 31 October 2015 01:18 > To: Anup Patel > Cc: David Woodhouse; Linux MTD; Rob Herring; Pawel Moll; Mark Rutland; > Catalin Marinas; Will Deacon; Sudeep Holla; Ian Campbell; Kumar Gala; Ray Jui; > Scott Branden; Florian Fainelli; Pramod Kumar; Vikram Prakash; Sandeep > Tripathy; Linux ARM Kernel; Device Tree; Linux Kernel; bcm-kernel-feedback-list > Subject: Re: [PATCH v5 2/3] mtd: brcmnand: Force 8bit mode before doing > nand_scan_ident() > > On Fri, Oct 30, 2015 at 12:29:20PM +0530, Anup Patel wrote: > > Just like other NAND controllers, > > ^^ That part isn't strictly true. While READ ID data only comes out on the lower 8 > bits, that doesn't *actually* mean you can't get valid data from a 16-bit bus in > general; you just have to drop the upper 8 bits. That's what these two commits > did for read ID and parameter page read commands: > > commit 3dad2344e92c6e1aeae42df1c4824f307c51bcc7 > Author: Brian Norris <computersforpeace@xxxxxxxxx> > Date: Wed Jan 29 14:08:12 2014 -0800 > > mtd: nand: force NAND_CMD_READID onto 8-bit bus > > commit bd9c6e99b58255b9de1982711ac9487c9a2f18be > Author: Brian Norris <computersforpeace@xxxxxxxxx> > Date: Fri Nov 29 22:04:28 2013 -0800 > > mtd: nand: don't use read_buf for 8-bit ONFI transfers > > > the NAND READID command only works > > in 8bit mode for all versions of BRCMNAND controller. > > But I presume *this* statement is actually true. This NAND controller doesn't > exactly give us a fully-flexible READID / read_byte / read_word command, as it > works at a higher level than that (although LOW_LEVEL_OP gives us this > flexibility now). I could imagine (though I never tested 16-bit NAND) that 16-bit > READID is broken. > > BTW, did you ask the HW designer about this? It'd be nice to be 100% sure. Yes, we had a discussed with HW designers and they confirmed that READID command will only work in 8bit mode. Regards, Anup -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
