Re: [PATCH v2] ARM: pxa: Move iotable mapping inside vmalloc region

From: Laurent Pinchart
Date: Wed Apr 09 2014 - 12:24:52 EST


Hi Ezequiel,

On Thursday 28 November 2013 21:00:43 Ezequiel Garcia wrote:
> In order to remove the following ugly message:
>
> BUG: mapping for 0x00000000 at 0xff000000 out of vmalloc space
>
> the iotable mappings should be re-located inside the vmalloc
> region. Such move was introduced at commit:
>
> commit 0536bdf33faff4d940ac094c77998cfac368cfff
> Author: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
> Date: Thu Aug 25 00:35:59 2011 -0400
>
> ARM: move iotable mappings within the vmalloc region
>
> While at it, condition the mapping to PXA25x and PXA27x, which
> are the only platforms where it's used.
>
> Cc: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
> Cc: Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>
> Cc: David Heidelberger <david.heidelberger@xxxxxxx>
> Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
> ---
> David,
>
> Is it possible for you to give this a try on your board?

I'm running into the same issue on a PXA270 system.

UNCACHED_PHYS_0 is used as an immediate operand to a mov instruction, and thus
needs to be encoded as a shifted 8-bit value. One simple solution would be to
hardcode it to 0xfd000000 (0xfe000000 is already used for the IMEMC mapping).

Another solution would be to keep the UNCACHED_PHYS_0 mapping at the end of
the vmalloc area (with a fix for the UL problem due to VMALLOC_END) and modify
pxa2[57]x_finish_suspend and pm_enter_standby_start to use an ldr instruction
instead of a move instruction to load the address.

As a side note, the IMEMC mapping seems unused, maybe we could thus reclaim it
and use 0xfe000000 for UNCACHED_PHYS_0.

Do you plan to submit a v3 of this patch ?

> arch/arm/mach-pxa/generic.c | 6 ++++--
> arch/arm/mach-pxa/include/mach/hardware.h | 5 +++--
> 2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/mach-pxa/generic.c b/arch/arm/mach-pxa/generic.c
> index 4225417..3c1b4fa 100644
> --- a/arch/arm/mach-pxa/generic.c
> +++ b/arch/arm/mach-pxa/generic.c
> @@ -83,11 +83,13 @@ static struct map_desc common_io_desc[] __initdata = {
> .pfn = __phys_to_pfn(0x40000000),
> .length = 0x02000000,
> .type = MT_DEVICE
> +#if defined(CONFIG_PXA25x) || defined(CONFIG_PXA27x)
> }, { /* UNCACHED_PHYS_0 */
> - .virtual = 0xff000000,
> + .virtual = UNCACHED_PHYS_0,
> .pfn = __phys_to_pfn(0x00000000),
> - .length = 0x00100000,
> + .length = UNCACHED_SIZE,
> .type = MT_DEVICE
> +#endif
> }
> };
>
> diff --git a/arch/arm/mach-pxa/include/mach/hardware.h
> b/arch/arm/mach-pxa/include/mach/hardware.h index ccb06e4..b365a72 100644
> --- a/arch/arm/mach-pxa/include/mach/hardware.h
> +++ b/arch/arm/mach-pxa/include/mach/hardware.h
> @@ -14,13 +14,14 @@
> #define __ASM_ARCH_HARDWARE_H
>
> #include <mach/addr-map.h>
> +#include <asm/pgtable.h>
>
> /*
> * Workarounds for at least 2 errata so far require this.
> * The mapping is set in mach-pxa/generic.c.
> */
> -#define UNCACHED_PHYS_0 0xff000000
> -#define UNCACHED_ADDR UNCACHED_PHYS_0
> +#define UNCACHED_PHYS_0 (VMALLOC_END - UNCACHED_SIZE)
> +#define UNCACHED_SIZE SZ_1M
>
> /*
> * Intel PXA2xx internal register mapping:

--
Regards,

Laurent Pinchart

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