From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from top.free-electrons.com ([176.31.233.9] helo=mail.free-electrons.com) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VeBjy-0005kA-U7 for linux-mtd@lists.infradead.org; Wed, 06 Nov 2013 22:38:24 +0000 Date: Wed, 6 Nov 2013 19:38:02 -0300 From: Ezequiel Garcia To: "Gupta, Pekon" Subject: Re: [PATCH 0/1] Fix OMAP2 NAND ONFI device detection Message-ID: <20131106223801.GA20184@localhost> References: <1383126788-27426-1-git-send-email-ezequiel.garcia@free-electrons.com> <20131030191414.GA16668@norris.computersforpeace.net> <20980858CB6D3A4BAE95CA194937D5E73EA2D41D@DBDE04.ent.ti.com> <20131030231956.GA2489@localhost> <20980858CB6D3A4BAE95CA194937D5E73EA31B19@DBDE04.ent.ti.com> <20131106211833.GB12624@localhost> <20980858CB6D3A4BAE95CA194937D5E73EA31BB3@DBDE04.ent.ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20980858CB6D3A4BAE95CA194937D5E73EA31BB3@DBDE04.ent.ti.com> Cc: "marek.belisko@gmail.com" , "linux-omap@vger.kernel.org" , Brian Norris , "linux-mtd@lists.infradead.org" , "Balbi, Felipe" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Nov 06, 2013 at 10:00:09PM +0000, Gupta, Pekon wrote: > > From: Ezequiel Garcia > [...] > > > But: on the other hand, I'd really like you to convince me as to > > why is it so bad to require the DTB to have the proper GPMC bus width. > > > No its not at all bad, all I want is either of the one way (not mixture of both). > - Either depend on DT completely (which is current case for all drivers) > - OR depend on ONFI and nand_flash_id[] for bus-width detection. > > > > Once again: > > 1. the NAND devices aren't hot-pluggable > > 2. the "user" (who is actually an engineer, not some regular dummy user) > > knows perfectly well the width of the device. > > > > What's the problem with describing the hardware in the DT and saving us > > lots of runtime re-configuration trouble? > > I agree with both your arguments above. > So shouldn't we kill NAND_BUSWIDTH_AUTO ? > And probably therefore NAND_BUSWIDTH_AUTO isn't that popular. > > Now what remains is ONFI probe, which should always happen in x8 mode. > So for that below patch should be sufficient .. > Hm.. that might work. Maybe you should submit this as RFC/PATCH to catch the attention of some more people. And we can keep discussing on this new idea... I should get an 8-bit module for the BBB, so this means I'll be able to run 8-bit and 16-bit tests. > ---------------------- > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index ec1db1e..d1220fb 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -2942,14 +2942,8 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, > chip->read_byte(mtd) != 'F' || chip->read_byte(mtd) != 'I') > return 0; > > - /* > - * ONFI must be probed in 8-bit mode or with NAND_BUSWIDTH_AUTO, not > - * with NAND_BUSWIDTH_16 > - */ > - if (chip->options & NAND_BUSWIDTH_16) { > - pr_err("ONFI cannot be probed in 16-bit mode; aborting\n"); > - return 0; > - } > + /* ONFI must be probed in 8-bit mode only */ > + nand_set_defaults(chip, 0); > > chip->cmdfunc(mtd, NAND_CMD_PARAM, 0, -1); > for (i = 0; i < 3; i++) { > @@ -2962,7 +2956,7 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, > > if (i == 3) { > pr_err("Could not find valid ONFI parameter page; aborting\n"); > - return 0; > + goto return_error; > } > > /* Check version */ > @@ -2980,7 +2974,7 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, > > if (!chip->onfi_version) { > pr_info("%s: unsupported ONFI version: %d\n", __func__, val); > - return 0; > + goto return_error; > } > > sanitize_string(p->manufacturer, sizeof(p->manufacturer)); > @@ -3033,6 +3027,12 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, > } > > return 1; > + > +return_error: > + /* revert original bus-width */ > + nand_set_defaults( chip->options & NAND_BUSWIDTH_16); > + return 0; > + > } > > /* > ------------------------- > > > with regards, pekon -- Ezequiel García, Free Electrons Embedded Linux, Kernel and Android Engineering http://free-electrons.com