[PATCH v3 4/7] of: configure the platform device dma parameters
From: arnd@arndb.de (Arnd Bergmann)
Date: 2014-05-29 19:24:54
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On Thursday 29 May 2014 10:08:10 Santosh Shilimkar wrote:
On Thursday 29 May 2014 10:01 AM, Linus Walleij wrote:quoted
On Wed, May 28, 2014 at 4:04 PM, Santosh Shilimkar [off-list ref] wrote:quoted
On Wednesday 28 May 2014 09:32 AM, Linus Walleij wrote:quoted
quoted
quoted
I suspect what you want is dma-ranges = <0x80000000 0 0x80000000>; to translate dma_addr_t 0x80000000-0xffffffff to phys_addr_t 0x0-0x7fffffff rather than phys_addr_t 0x800000000-0x87fffffff.Interesting. Where does the ROM address space resides on integrator then considering address 0 is used for DMA.The ROM is at physical address 0x20000000, don't ask me why The RAM is typically at 0x00000000-0x0fffffff, on up to four parallell tiles, i.e. up to four completely independent CPUs are booted off the same ROM and using a set of shared peripherals.The reason I asked the question because most of the ARM SOC I came across aren't using the RAM phys address 0 and thought was because of boot architecture with ROM occupying that address with reset vector starting at address 0. That was one of the main reason we had description on max_*pfn on ARM w.r.t to other acrhes. Will corner ARM guys to understand bit more about it in some conference
If this is anything like the versatile express, the reason it works is probably because there is another microcontroller in the system that does the bootstrap and is able to load code into RAM before turning on the main CPU. Arnd