From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH] mtd: nand: denali: allow to override max_banks from DT property Date: Fri, 25 Mar 2016 15:45:20 +0100 Message-ID: <20160325154520.199b0863@bbrezillon> References: <1458822277-31428-1-git-send-email-yamada.masahiro@socionext.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1458822277-31428-1-git-send-email-yamada.masahiro@socionext.com> Sender: linux-kernel-owner@vger.kernel.org To: Masahiro Yamada Cc: linux-mtd@lists.infradead.org, Graham Moore , Dinh Nguyen , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Richard Weinberger , Kumar Gala , Ian Campbell , Brian Norris , Rob Herring , David Woodhouse , Pawel Moll , Mark Rutland List-Id: devicetree@vger.kernel.org On Thu, 24 Mar 2016 21:24:37 +0900 Masahiro Yamada wrote: > Commit 271707b1d817 ("mtd: nand: denali: max_banks calculation > changed in revision 5.1") supported the new encoding of the "n_banks" > bits of the "features" register, but there is an unfortunate case > that is not covered by that commit. > > Panasonic (its System LSI division is now Socionext) bought several > versions of this IP. The IP released for Panasonic around Feb. 2012 > is revision 5 and uses the old encoding for n_banks (2 << n_banks). > While the one released around Nov. 2012 is also revision 5, but it > uses the new encoding (1 << n_banks). > > The revision register cannot distinguish these two incompatible > hardware. I guess this IP series is not well-organized. I could not > find any alternative but giving max_banks from DT property. Hm, shouldn't that be addressed with a new compatible instead of adding a extra property? > > This commit works around the problem by allowing DT to set the > max_banks forcibly. Of course, this DT property can be optional if > the auto detection based on the hardware registers works well. > > Signed-off-by: Masahiro Yamada > --- > > Documentation/devicetree/bindings/mtd/denali-nand.txt | 4 ++++ > drivers/mtd/nand/denali.c | 3 ++- > drivers/mtd/nand/denali_dt.c | 3 +++ > 3 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/mtd/denali-nand.txt b/Documentation/devicetree/bindings/mtd/denali-nand.txt > index 785b825..78c250d 100644 > --- a/Documentation/devicetree/bindings/mtd/denali-nand.txt > +++ b/Documentation/devicetree/bindings/mtd/denali-nand.txt > @@ -7,6 +7,10 @@ Required properties: > - interrupts : The interrupt number. > - dma-mask : DMA bit mask > > +Optional properties: > + - max-banks : Maximum number of banks supported by hardware. If not > + specified, it is determined based on the "features" register of hardware. > + You might want to prefix that with "denali,". > The device tree may optionally contain sub-nodes describing partitions of the > address space. See partition.txt for more detail. > > diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c > index 30bf5f6..e18b569 100644 > --- a/drivers/mtd/nand/denali.c > +++ b/drivers/mtd/nand/denali.c > @@ -1353,7 +1353,8 @@ static void denali_hw_init(struct denali_nand_info *denali) > */ > denali->bbtskipbytes = ioread32(denali->flash_reg + > SPARE_AREA_SKIP_BYTES); > - detect_max_banks(denali); > + if (!denali->max_banks) > + detect_max_banks(denali); > denali_nand_reset(denali); > iowrite32(0x0F, denali->flash_reg + RB_PIN_ENABLED); > iowrite32(CHIP_EN_DONT_CARE__FLAG, > diff --git a/drivers/mtd/nand/denali_dt.c b/drivers/mtd/nand/denali_dt.c > index 0cb1e8d..be55db8 100644 > --- a/drivers/mtd/nand/denali_dt.c > +++ b/drivers/mtd/nand/denali_dt.c > @@ -85,6 +85,9 @@ static int denali_dt_probe(struct platform_device *ofdev) > denali->dev->dma_mask = NULL; > } > > + of_property_read_u32(ofdev->dev.of_node, "max-banks", > + &denali->max_banks); > + > dt->clk = devm_clk_get(&ofdev->dev, NULL); > if (IS_ERR(dt->clk)) { > dev_err(&ofdev->dev, "no clk available\n"); -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com