Re: [FOR 3.4 PATCH 5/6] atmel/nand: add DT support

On 10:31 Sun 29 Jan     , Simon Glass wrote:

Hi,

On Fri, Jan 27, 2012 at 9:10 PM, Jean-Christophe PLAGNIOL-VILLARD
[off-list ref] wrote:

quoted

use a local copy of board informatin and fill with DT data

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org>
Cc: Nicolas Ferre <redacted>
Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Cc: linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
---
 .../devicetree/bindings/mtd/atmel-nand.txt         |   41 ++++++++
 drivers/mtd/nand/atmel_nand.c                      |  107 ++++++++++++++++----
 2 files changed, 130 insertions(+), 18 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/mtd/atmel-nand.txt

diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand.txt b/Documentation/devicetree/bindings/mtd/atmel-nand.txt
new file mode 100644
index 0000000..a910ab9
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/atmel-nand.txt

@@ -0,0 +1,41 @@
+Atmel NAND flash
+
+Required properties:
+- compatible : "atmel,at91rm9200-nand".
+- reg : should specify localbus address and size used for the chip,
+       and if availlable the ECC.
+- atmel,nand-addr-offset : offset for the address latch.
+- atmel,nand-cmd-offset : offset for the command latch.
+- #address-cells, #size-cells : Must be present if the device has sub-nodes
+  representing partitions.
+
+- gpios : specifies the gpio pins to control the NAND device. detect is an
+  optional gpio and may be set to 0 if not present.

What does this mean please? What is 'detect' and what 'control' do the
gpios provide?

Below you have two GPIOs pioC 13 and pioC 14. I think the binding
should document the two GPIOs, the order, and what they are for.

no as it's said in the binding the detect pin is optional

quoted

+
+Optional properties:
+- nand-ecc-mode : String, operation mode of the NAND ecc mode, soft by default.
+  Supported values are: "none", "soft", "hw", "hw_syndrome", "hw_oob_first",
+  "soft_bch".
+- nand-bus-width : 8 or 16 bus width if not present 8
+- nand-on-flash-bbt: boolean to enable on flash bbt option if not present false
+
+Examples:
+nand0: nand@40000000,0 {
+       compatible = "atmel,at91rm9200-nand";
+       #address-cells = <1>;
+       #size-cells = <1>;
+       reg = <0x40000000 0x10000000
+              0xffffe800 0x200
+             >;
+       atmel,nand-addr-offset = <21>;
+       atmel,nand-cmd-offset = <22>;
+       nand-on-flash-bbt = <1>;
+       nand-ecc-mode = "soft";
+       gpios = <&pioC 13 0
+                &pioC 14 0
+                0

Sorry, I haven't seen this before, perhaps it is a standard thing in
Linux. Does 0 mean end of list? Can we not just use the property's
size value for this?

0 means not used as specified in the DT

Best Regards,
J.