Re: [PATCH 0/9] ARM: dts: Various OMAP2+ device-tree updates

[Javier Martinez Canillas <martinez.javier@gmail.com>]

On Thu, Mar 14, 2013 at 3:57 PM, Benoit Cousson <b-cousson@ti.com> wrote:
> Salut Jon,
>
> On 03/08/2013 06:27 PM, Jon Hunter wrote:
>> Various OMAP device-tree updates for PMU, DMA, GPIO, GPMC and boards.
>>
>> The DMA, PMU and OMAP3430 SDP board changes have been sent before
>> individually but re-sending here as a complete series for v3.10.
>>
>> This is based upon v3.9-rc1 and the OMAP3 GPMC binding from Florian
>> Vaussard [1] and OMAP5 DT SPI patch from Felipe Balbi [2].
>>
>> [1] https://patchwork.kernel.org/patch/2057111/
>
> I've tried to follow the series review, and it seems that Florian was
> considering sending some other patches. It is not clear if this is a new
> version of the series or some additional patches.
>

Hi Benoit,

According to [1] Jon suggested that it was not necessary to map all
the 16MB for the GPMC mapped register address space since in practice
is a very small fraction of that size is used.

I had the following patch but I did never post it because Jon said
that the I/O memory mapping is page-aligned and the minimum page
size for ARM is 4KB anyways, so there is no functional difference
between using 0x1000 or 0x02d0.

But now reading [2] I see that you prefer to do what the documentation
said and don't assume any the page size / alignment.

[2]: https://patchwork.kernel.org/patch/2239741/

>From 68edff5a102bb8fc81e006738baa456eb69f080a Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Date: Wed, 27 Feb 2013 02:30:51 +0100
Subject: [PATCH] ARM: dts: OMAP3: reduce GPMC mapped registers address space

Currently the OMAP General-Purpose Memory Controller (GPMC) device
node maps 16 MB of address space for its hardware registers.

This is because the OMAP Technical Reference Manual says that the
GPMC module register address space size is 16 MB. But in practice
the maximum address offset used by a GPMC register is 0x02d0.

So, there is no need to map such a big address space for GPMC regs.

This change was suggested by Jon Hunter [1].

[1]: https://patchwork.kernel.org/patch/2057111/

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
---
 arch/arm/boot/dts/omap3.dtsi |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/boot/dts/omap3.dtsi b/arch/arm/boot/dts/omap3.dtsi
index 2ddae38..a60eaf1 100644
--- a/arch/arm/boot/dts/omap3.dtsi
+++ b/arch/arm/boot/dts/omap3.dtsi
@@ -407,7 +407,7 @@
 		gpmc: gpmc@6e000000 {
 			compatible = "ti,omap3430-gpmc";
 			ti,hwmods = "gpmc";
-			reg = <0x6e000000 0x1000000>;
+			reg = <0x6e000000 0x02d0>;
 			interrupts = <20>;
 			gpmc,num-cs = <8>;
 			gpmc,num-waitpins = <4>;
-- 
1.7.7.6