Re: [PATCH 0/2] Experimental Amiga Zorro ESP driver

[Tuomas Vainikka <tuomas.vainikka@aalto.fi>]

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On 08/18/2013 11:58 AM, Michael Schmitz wrote:
> Geert,
>> On Sun, Aug 18, 2013 at 4:05 AM, Michael Schmitz 
>> <schmitzmic@gmail.com> wrote:
>>>>>> [  301.880000] esp: esp0: Reconnect IRQ2 timeout
>>
>> Beware that this message (incl. the number) is hardcoded in
>> drivers/scsi/esp_scsi.c:
>>
>>         if (i == ESP_RESELECT_TAG_LIMIT) {
>>                 printk(KERN_ERR PFX "esp%d: Reconnect IRQ2 timeout\n",
>>                        esp->host->unique_id);
>>                 return NULL;
>>         }
>>
>> The driver prints "IRQ1" or "IRQ2".
>>
>> Fortunately, IRQ_AMIGA_PORTS is 2, but this is purely coincidentally...
>
> The driver attempts to DMA two bytes - can the DMA on the Zorro ESP 
> cards handle such short transfers?
>
> I'll also need to check the command_block and command_block_dma 
> addresses - does the DMA require virtual or physical addresses?
>
>>>>> Are there interrupts logged for IRQ2 at all (cat 
>>>>> /proc/interrupts)? It
>>>>> looks to me as though all DMA transfers fail (the first command to 
>>>>> fail is
>>>>> READ_CAPACITY which would usually be issued right after IDENTIFY 
>>>>> IIRC).
>>>> root@amiga:/# cat /proc/interrupts
>>>>            CPU0
>>>>   2:    1066320      auto  CIAA, zorro8390, ide0, Amiga Zorro ESP
>>>>   6:     456970      auto  CIAB
>>>>   8:      38239     amiga  serial TX
>>>>   9:          0     amiga  floppy_dma
>>>>  12:     315934     amiga  fb vertb handler
>>>>  13:     315741     amiga  serial status
>>>>  15:          0     amiga  DMA sound
>>>>  19:        401     amiga  serial RX
>>>>  23:          1       cia  floppy_timer
>>>>  25:          0       cia  amikbd
>>>>  27:     456971       cia  timer
>>>> ERR:          0
>>>>
>>>> Seems like IRQ2 is very popular, so it's hard to say which device has
>>>> generated the interrupts...
>>> Yep - you'll be guaranteed to get a few IDE interrupts just by 
>>> calling up
>>> cat - might be possible to get away without too much interrupts 
>>> generated if
>>> it's all in the buffer cache - try whether the interrupt count 
>>> changes after
>>> a few repetitions of that command.
>>>
>>> Might require more elaborate IRQ bookkeeping though.
>>
>> I guess scsi_esp_intr() is called a lot, as it's a shared interrupt?
>
> That's right - it will indeed be called a lot.
>
>> Can you add some debug prints there, to see if any of the conditions the
>> esp core checks are met?
> The code in question polls for completion in the ESP chip interrupt 
> register, so checking in scsi_esp_intr won't help there. I suspect the 
> ESP gets stuck because the DMA operation never completes. Wonder 
> whether we can just do PIO in send_dma_cmd() in these cases ...
>
The original blz1230 / blz2060 drivers did PIO commands. I attached a 
log of modprobing first without interrupt messages and then with the 
interrupt messages, because, indeed, the zorro_esp_irq_pending function 
gets called a lot, and it takes forever to printk those messages. I have 
no idea about the correct iomappings for the registers, nor do I know 
about the correct sizes for them. I have no idea where to use physical 
addresses and where to use virtual addresses...

What is the difference between ioremap() and ZTWO_VADDR() and which one 
should be used where?

-Tuomas


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