Re: [PATCH v3 2/2] arm64: dts: Add BRCM IPROC NAND DT node for NS2

From: Ray Jui
Date: Tue Oct 27 2015 - 20:47:12 EST

On 10/27/2015 5:39 PM, Brian Norris wrote:
On Tue, Oct 27, 2015 at 05:25:32PM -0700, Ray Jui wrote:
On 10/27/2015 5:19 PM, Brian Norris wrote:
On Fri, Oct 23, 2015 at 10:46:13AM +0530, Anup Patel wrote:
diff --git a/arch/arm64/boot/dts/broadcom/ns2.dtsi b/arch/arm64/boot/dts/broadcom/ns2.dtsi
index f603277..9610822 100644
--- a/arch/arm64/boot/dts/broadcom/ns2.dtsi
+++ b/arch/arm64/boot/dts/broadcom/ns2.dtsi
@@ -212,5 +212,19 @@
compatible = "brcm,iproc-rng200";
reg = <0x66220000 0x28>;
+ nand: nand@66460000 {
+ compatible = "brcm,nand-iproc", "brcm,brcmnand-v6.1";

Technically, the binding says you should also have "brcm,brcmnand" as a
last resort. Otherwise (for the NAND parts):

I believe Anup was seeing issues when both "brcm,nand-iproc" and
"brcm,brcmnand" are present.

Note "brcm,nand-iproc" invokes 'iproc_nand_probe', which calls
'brcmnand_probe' in the end.

"brcm,brcmnand" invokes 'brcmstb_nand_probe', which also calls
'brcmstb_probe', but without all the prep configuration required for

Ah, I forgot about that problem. That seems like an OF infrastructure
issue that could be fixed. We could lump these drivers back together,
and make sure that "brcm,nand-iproc" gets the priority in the
of_device_id list.

Or we could just relax the DT binding.

But wait, wouldn't cygnus already have that problem? You're using the
binding I suggested in arch/arm/boot/dts/bcm-cygnus.dtsi.

Interestingly, we do not see this problem with Cygnus or NSP, but only on NS2 (arm64 based). There may be a difference between how OF devices are instantiated between arm and arm64?

Oh, and I see we hacked this one in drivers/mtd/nand/brcmnand/Makefile:

# link order matters; don't link the more generic brcmstb_nand.o before the
# more specific iproc_nand.o, for instance

Yes, I see that too (after sending out my previous email, :)). Maybe Anup can help to elaborate on the problem. I'm now getting a bit confused on how the problem can surface on NS2.

But in general, I think it's a good idea to relax the requirement in the DT binding document to not require "brcm,brcmnand", in the case when "brcm,nand-iproc" and "brcm,nand-bcm63138" are present.



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