From: Gary Thomas <gary@mlbassoc•com>
To: Scott Wood <scottwood@freescale•com>
Cc: linuxppc-dev <linuxppc-dev@ozlabs•org>, avorontsov@ru•mvista.com
Subject: Re: PCI on 834x
Date: Thu, 25 Feb 2010 16:43:19 -0700 [thread overview]
Message-ID: <4B870B17.7080701@mlbassoc.com> (raw)
In-Reply-To: <4B86EAA3.8000301@freescale.com>
On 02/25/2010 02:24 PM, Scott Wood wrote:
> Gary Thomas wrote:
>> On 02/25/2010 02:03 PM, Scott Wood wrote:
>>> Gary, can you check that the MMIO addresses are going to the PCI bus as-is, and aren't being translated down to zero? I.e. POTARn should equal POBARn, and likewise in the device
>>> tree's pci node's ranges.
>>
>> Hmm, that doesn't match with how I've always had this setup. I have:
>> POTAR0 = 0x00000000
>> POTBR0 = 0x000C0000 (0xC0000000 >> 12)
>>
>> My device tree mappings are:
>> ranges = <0x02000000 0x0 0xC0000000 0xC0000000 0x0 0x10000000
>> 0x01000000 0x0 0x00000000 0xB8000000 0x0 0x00100000>
>
> That ranges property says that host address 0xc0000000 maps to PCI address 0xc0000000, so Linux will program the BAR to 0xc0000000, but the actual accesses will go elsewhere
> because POTAR0 is zero.
>
> Setting POTAR to zero is also a bad idea because it's aliasing your DMA window (it may work in certain situations based on who's initiating the transaction, but it seems like it's
> asking for trouble), plus it seems some cards just don't like address zero.
>
> Try setting POTAR0 to 0x000c0000 and see what happens.
Sadly, that doesn't work at all - neither RedBoot nor Linux
can talk to any of the PCI devices.
--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
------------------------------------------------------------
next prev parent reply other threads:[~2010-02-25 23:43 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-24 15:49 PCI on 834x Gary Thomas
2010-02-24 18:48 ` Scott Wood
2010-02-24 19:14 ` Gary Thomas
2010-02-24 19:31 ` Scott Wood
2010-02-24 19:47 ` Gary Thomas
2010-02-24 20:26 ` Scott Wood
2010-02-24 20:51 ` Anton Vorontsov
2010-02-24 22:14 ` Gary Thomas
2010-02-24 22:25 ` Kumar Gala
2010-02-24 23:08 ` Gary Thomas
2010-02-25 14:25 ` Gary Thomas
2010-02-25 20:49 ` Benjamin Herrenschmidt
2010-02-25 21:03 ` Scott Wood
2010-02-25 21:11 ` Gary Thomas
2010-02-25 21:24 ` Scott Wood
2010-02-25 23:43 ` Gary Thomas [this message]
2010-02-25 23:49 ` Scott Wood
2010-02-25 22:36 ` Benjamin Herrenschmidt
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