Re: [PATCH] pata_of_platform: fix no irq handling

From: "Steven A. Falco" <sfalco@harris.com>
To: avorontsov@ru.mvista.com
Cc: "Sparks, Sam" <SSparks@aclaratech.com>,
	linuxppc-dev@ozlabs.org, linux-ide@vger.kernel.org,
	Stefan Roese <sr@denx.de>, Jeff Garzik <jgarzik@pobox.com>
Subject: Re: [PATCH] pata_of_platform: fix no irq handling
Date: Wed, 13 Aug 2008 17:25:59 -0400	[thread overview]
Message-ID: <48A35167.6030001@harris.com> (raw)
In-Reply-To: <20080812143110.GA23961@oksana.dev.rtsoft.ru>

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Anton Vorontsov wrote:
> On Tue, Aug 12, 2008 at 06:18:42PM +0400, Sergei Shtylyov wrote:
>   
>> Anton Vorontsov wrote:
>>
>>     
>>>>>> 1. IDE status read does not work. (But am I understand correctly
>>>>>>   that IDE works well if IRQ is unspecified? Then this is hardly
>>>>>>   an issue.)
>>>>>> 2. IDE interrupt comes when it should not. I'd recommend to use
>>>>>>   oscilloscope to find out what is happening there, that is, if
>>>>>>   the drive actually deasserts its irq line after status read.
>>>>>>   If so, than this could be a PIC problem.
>>>>>>             
>>>>>> What is the platform on which you're observing the issue, btw?
>>>>>>             
>>>>> Another possibility is that you got the wrong interrupt number
>>>>> in the device-tree...
>>>>>           
>>>>> Ben.
>>>>>           
>>>> The platform is the AMCC Sequoia board.  We've built a little adapter to
>>>> connect a compact flash card to the processor bus.  I believe the
>>>> interrupt selection in the device tree is correct, and I've checked over
>>>> the u-boot settings for the IRQ line (active high, level sensitive). 
>>>>         
>>> IDE IRQs are active-low.
>>>       
>>    Only on the PCI and only in the native mode. Natively, the IDE INTRQ  
>> signal is active-high, rising edge triggering, as on ISA. You seem to 
>> have an invertor somewhere, if it's not a PCI chip...
>>     
>
> Ugh. Right you are, as always. I've just looked into mpc8349emitx
> schematics, there is indeed an inverter on the irq line.
>
> CF in True IDE mode is active-high, sorry.
>   

Ok, just to close this issue, my CF device is now working perfectly. 
Two problems, both my fault.  1) I thought the alternate registers used
the same reg-shift and offset, so the alt_command and alt_status were at
the wrong address, and 2) I was missing a pull-down on the IRQ line -
the sequoia eval board has it in the schematic, but it is marked "not
populated".

    Thanks to all for your comments and help,
    Steve

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