linux-kernel - Re: [PATCH V3] pci: exynos: split into two parts such as Synopsys part and Exynos part

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Message-ID: <523FD286.608@ti.com>
Date:	Mon, 23 Sep 2013 11:02:54 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Pratyush Anand <pratyush.anand@...com>
CC:	Arnd Bergmann <arnd@...db.de>, Jingoo Han <jg1.han@...sung.com>,
	"'Bjorn Helgaas'" <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"'Kukjin Kim'" <kgene.kim@...sung.com>,
	Mohit KUMAR DCG <Mohit.KUMAR@...com>,
	"'Sean Cross'" <xobs@...agi.com>,
	"'Thierry Reding'" <thierry.reding@...il.com>,
	"'SRIKANTH TUMKUR SHIVANAND'" <ts.srikanth@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH V3] pci: exynos: split into two parts such as Synopsys
 part and Exynos part

Hi Pratyush,

On Monday 23 September 2013 09:44 AM, Pratyush Anand wrote:
> Hi Kishon,
> 
> 
> On Sun, Sep 22, 2013 at 07:16:34PM +0800, Kishon Vijay Abraham I wrote:
>> Hi Arnd,
>>
>> Thanks for replying :-)
>>
>> On Sunday 22 September 2013 03:33 AM, Arnd Bergmann wrote:
>>> On Saturday 21 September 2013, Kishon Vijay Abraham I wrote:
>>>> {
>>>>         u32 val;
>>>>         void __iomem *val1;
>>>>         void __iomem *dbi_base = pp->dbi_base;
>>>>
>>>>         /* Program viewport 0 : INBOUND : MEMORY*/
>>>>         val = PCIE_ATU_REGION_INBOUND | (0 & 0xF);
>>>>         dw_pcie_writel_rc(pp, val, dbi_base + PCIE_ATU_VIEWPORT);
>>>>         val1 = ioremap(0x80000000, 0x5fffffff);
>>>
>>> The ioremap here makes no sense at all, and I suspect it will fail anyway,
>>> because you exhaust the vmalloc area size, but since the value is not
>>> used anywhere, it won't matter.
>>>
>>>>         dw_pcie_writel_rc(pp, 0x80000000, dbi_base + PCIE_ATU_LOWER_BASE);
>>>>         dw_pcie_writel_rc(pp, 0, dbi_base + PCIE_ATU_UPPER_BASE);
>>>>         /* in_mem_size must be in power of 2 */
>>>>         dw_pcie_writel_rc(pp, 0x5FFFFFFF, dbi_base + PCIE_ATU_LIMIT);
> 
> This is wrong. You should program here 0xBFFFFFFF.

That dint help :-(

Btw if we hadn't programmed inbound translation table, the address will go
untranslated (according to the data book). I guess that's how it was working
for Jingoo Han.

**
3.10.4
Inbound iATU Operation

When there is no match, then the address is untranslated
**

> 
> Translation rule is as follows:
> 
> Region between "Start Address" and "End Address" is translated to
> "Target Address" with region size = "End Address" - "Start Address".
> Where: Start Address = (PCIE_ATU_UPPER_BASE | PCIE_ATU_LOWER_BASE)
>         End Address = (PCIE_ATU_UPPER_BASE | PCIE_ATU_LIMIT)
>         Target Address = (PCIE_ATU_UPPER_TARGET | PCIE_ATU_LOWER_TARGET) 
> 
>>>>         dw_pcie_writel_rc(pp, 0x80000000, dbi_base + PCIE_ATU_LOWER_TARGET);
>>>>         dw_pcie_writel_rc(pp, 0, dbi_base + PCIE_ATU_UPPER_TARGET);
>>>
>>> These numbers need to come from somewhere, you shouldn't just hardcode them, 
>>
>> right. I'm still in the process of getting it work ;-)
>>>
>>> I guess you should either program an inbound window covering the entire 64-bit
>>> address space, or you should look at the top-level "memory" nodes to find
>>> the location of physical RAM.
>>>
>>> I can't see anything wrong with the way it's set up though, unless you have
>>> an IOMMU. Can you confirm that there is no IOMMU (aka SMMU) in your system
>>> that handles the PCIe root complex?
>>
>> There is a MMU for PCIe root complex but that's disabled.
>>>
>>>> I somehow starting to doubt the DMA address programmed in the ethernet card
>>>> which is in my RAM address range (0x80000000 to 0xBFFFFFFF). Should this
>>>> address be programmed in the BAR of the ethernet card? How should it be done?
>>>
>>> No, it should not be in the BAR. The ethernet device driver calls dma_map_*
>>> or pci_map_* interfaces to get a valid token that can be passed into the
>>> device registers that are starting the DMA. You have to ensure that the
>>> dma_map_ops for the device return the value that is set up in the translation.
>>>
>>> The normal case is an identity mapping between device DMA space and host
>>> memory space, i.e. PCIE_ATU_LOWER_TARGET == PCIE_ATU_LOWER_BASE, so
>>> in the dma_map_single implementation, phys_addr_t == dma_addr_t.
>>>
>>> If you set up the dma_addr_t space to start at 0 instead, you have to add
>>> the offset in the dma_map_ops.
>>
>> My DMA address is in 0x80000000 to 0xBFFFFFFF range and I program my inbound
>> translation for this range. Not sure what is missing still :-(
> 
> Hope, above modification helps. Let me know.
> 
> Regards
> Pratyush
>>
>> Thanks
>> Kishon

Thanks
Kishon

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