From: Santosh Shilimkar <santosh.shilimkar@ti.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Grant Likely <grant.likely@linaro.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Russell King <linux@arm.linux.org.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rob Herring <robh+dt@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Olof Johansson <olof@lixom.net>
Subject: Re: [PATCH v3 4/7] of: configure the platform device dma parameters
Date: Thu, 29 May 2014 16:04:49 -0400 [thread overview]
Message-ID: <538792E1.3020500@ti.com> (raw)
In-Reply-To: <4755790.VgRQTHz3K1@wuerfel>
On Thursday 29 May 2014 03:24 PM, Arnd Bergmann wrote:
> On Thursday 29 May 2014 10:08:10 Santosh Shilimkar wrote:
>> On Thursday 29 May 2014 10:01 AM, Linus Walleij wrote:
>>> On Wed, May 28, 2014 at 4:04 PM, Santosh Shilimkar
>>> <santosh.shilimkar@ti.com> wrote:
>>>> On Wednesday 28 May 2014 09:32 AM, Linus Walleij wrote:
>>>
>>>>>> 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.
>
That make sense now. Thanks for those extra bits.
Regards,
Santosh
next prev parent reply other threads:[~2014-05-29 20:05 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-24 15:30 [PATCH v3 0/7] of: setup dma parameters using dma-ranges and dma-coherent Santosh Shilimkar
2014-04-24 15:30 ` [PATCH v3 1/7] device: introduce per device dma_pfn_offset Santosh Shilimkar
2014-05-02 1:01 ` Rob Herring
2014-04-24 15:30 ` [PATCH v3 2/7] of: introduce of_dma_get_range() helper Santosh Shilimkar
2014-05-02 1:06 ` Rob Herring
2014-04-24 15:30 ` [PATCH v3 3/7] of: introduce of_dma_is_coherent() helper Santosh Shilimkar
2014-05-02 0:56 ` Rob Herring
2014-05-05 21:45 ` Santosh Shilimkar
2014-05-05 22:06 ` Rob Herring
2014-04-24 15:30 ` [PATCH v3 4/7] of: configure the platform device dma parameters Santosh Shilimkar
2014-04-29 14:41 ` Grant Likely
2014-04-30 14:19 ` Santosh Shilimkar
2014-05-01 13:12 ` Grant Likely
2014-05-01 13:16 ` Santosh Shilimkar
2014-05-02 9:58 ` Arnd Bergmann
2014-05-02 13:13 ` Santosh Shilimkar
2014-05-02 15:13 ` Arnd Bergmann
2014-05-27 12:56 ` Grant Likely
2014-05-27 13:30 ` Arnd Bergmann
2014-05-28 8:23 ` Linus Walleij
2014-05-28 13:29 ` Arnd Bergmann
2014-05-28 13:32 ` Linus Walleij
2014-05-28 14:04 ` Santosh Shilimkar
2014-05-29 14:01 ` Linus Walleij
2014-05-29 14:08 ` Santosh Shilimkar
2014-05-29 19:24 ` Arnd Bergmann
2014-05-29 20:04 ` Santosh Shilimkar [this message]
2014-05-02 0:49 ` Rob Herring
2014-05-05 21:47 ` Santosh Shilimkar
2014-05-05 22:08 ` Rob Herring
2014-05-06 9:40 ` Arnd Bergmann
2014-05-06 20:44 ` Santosh Shilimkar
2014-05-07 13:24 ` Santosh Shilimkar
2014-05-02 16:54 ` Bjorn Helgaas
2014-05-02 18:59 ` Arnd Bergmann
2014-05-05 20:45 ` Bjorn Helgaas
2014-05-05 20:55 ` Arnd Bergmann
2014-05-05 22:28 ` Bjorn Helgaas
2014-05-06 3:44 ` Benjamin Herrenschmidt
2014-05-06 9:54 ` Arnd Bergmann
2014-05-06 13:32 ` Santosh Shilimkar
2014-04-24 15:30 ` [PATCH v3 5/7] ARM: dma: Use dma_pfn_offset for dma address translation Santosh Shilimkar
2014-05-02 14:32 ` Rob Herring
2014-05-02 14:58 ` Russell King - ARM Linux
2014-05-02 15:05 ` Santosh Shilimkar
2014-05-05 19:50 ` Russell King - ARM Linux
2014-05-05 21:43 ` Santosh Shilimkar
2014-04-24 15:30 ` [PATCH v3 6/7] ARM: dma: implement set_arch_dma_coherent_ops() Santosh Shilimkar
2014-05-02 0:58 ` Rob Herring
2014-04-24 15:30 ` [PATCH v3 7/7] ARM: dma: use phys_addr_t in __dma_page_[cpu_to_dev/dev_to_cpu] Santosh Shilimkar
2014-04-24 15:45 ` Will Deacon
2014-05-01 13:19 ` [PATCH v3 0/7] of: setup dma parameters using dma-ranges and dma-coherent Santosh Shilimkar
2014-05-01 13:25 ` Russell King - ARM Linux
2014-05-01 14:06 ` Santosh Shilimkar
2014-05-02 14:41 ` Rob Herring
2014-05-02 16:41 ` Santosh Shilimkar
2014-05-14 10:12 ` Grant Likely
2014-06-02 6:37 ` Shawn Guo
2014-06-02 13:24 ` Santosh Shilimkar
2014-06-02 15:06 ` Arnd Bergmann
2014-06-02 15:54 ` Santosh Shilimkar
2014-06-02 19:00 ` Arnd Bergmann
2014-06-02 19:08 ` Santosh Shilimkar
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