Re: [PATCH v2 1/5] dt-binding: mtd: nand: Document gpio-cs property

Hi Rob,

Rob Herring [off-list ref] wrote on Mon, 10 May 2021 11:51:25 -0500:

On Mon, May 10, 2021 at 12:40:47PM +0200, Miquel Raynal wrote:

quoted

To reach higher capacities, arrays of chips are now pretty common.
Unfortunately, most of the controllers have been designed a decade ago
and did not all anticipate the need for several chip-selects. The new
cs-gpios property allows to workaround this limitation by adding as many
GPIO chip-select as needed.  

Subject and example have wrong property name.

True.

quoted

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 .../devicetree/bindings/mtd/nand-controller.yaml | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/mtd/nand-controller.yaml b/Documentation/devicetree/bindings/mtd/nand-controller.yaml
index 678b39952502..70a400e385b2 100644
--- a/Documentation/devicetree/bindings/mtd/nand-controller.yaml
+++ b/Documentation/devicetree/bindings/mtd/nand-controller.yaml

@@ -38,6 +38,15 @@ properties:
 
   ranges: true
 
+  cs-gpios:
+    description:
+      Array of chip-select available to the controller. The first
+      entries are a 1:1 mapping of the available chip-select on the
+      NAND controller (even if they are not used). As many additional
+      chip-select as needed may follow and should be phandles of GPIO
+      lines. 'reg' entries of the NAND chip subnodes become indexes of
+      this array when this property is present.  

Can we put some 'maxItems' value here. I want to make the meta-schema 
enforce that. I realize there's not really one here, but a 'should be 
enough' value is fine. We can bump it up if needed.

Ok, I already have an example with 8 entries, we can set maxItems to 8
and see how it goes.

Please ignore v3 which was sent to fix another unrelated issue, at the
same time you reviewed v2.

quoted

+
 patternProperties:
   "^nand@[a-f0-9]$":
     type: object

@@ -164,14 +173,19 @@ examples:
     nand-controller {
       #address-cells = <1>;
       #size-cells = <0>;
+      gpio-cs = <0>, <&gpioA 1>; /* A single native CS is available */
 
       /* controller specific properties */
 
       nand@0 {
-        reg = <0>;
+        reg = <0>; /* Native CS */
         nand-use-soft-ecc-engine;
         nand-ecc-algo = "bch";
 
         /* controller specific properties */
       };
+
+      nand@1 {
+        reg = <1>; /* GPIO CS */
+      };
     };

-- 
2.27.0
  

Thanks,
Miquèl