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List:       linux1394-devel
Subject:    HCControl.noByteSwapData (was Re: Iso header timestamp)
From:       Stefan Richter <stefanr () s5r6 ! in-berlin ! de>
Date:       2008-07-16 16:09:40
Message-ID: tkrat.525f8a6055d18628 () s5r6 ! in-berlin ! de
[Download RAW message or body]

On 14 Jul, Stefan Richter wrote:
> Pieter Palmers wrote:
>> On a slightly different topic:
>> 
>> Is the OHCI hardware byte-swap feature used in the new modules?
>> If not: why not?
> 
> Do you mean HCControl.noByteSwapData (OHCI 1.1 table 5-12)?
> 
> "Motherboard implementations" (whatever that is) are not required to 
> implement it.

I checked whether I can switch the flag on on my cards.  But I didn't
test yet if it actually works because I let fw-ohci switch it off again
right away; see below.  According to that,

    Agere FW323 (OHCI 1.0, on a motherboard)
    ALi M5271
    NEC something (OHCI 1.0, OrangeLink card)
    TI TSB43AB22(A?)
    TI TSB82AA2
    VIA VT6306
    VIA VT6307 (OHCI 1.1, on a motherboard)

do all support the flag.

--- linux.orig/drivers/firewire/fw-ohci.c
+++ linux/drivers/firewire/fw-ohci.c
@@ -1465,6 +1465,13 @@ static int ohci_enable(struct fw_card *c
 		return -EIO;
 	}
 
+	reg_write(ohci, OHCI1394_HCControlSet,
+		  OHCI1394_HCControl_noByteSwapData);
+	fw_notify("device %s %s noByteSwapData\n", dev->dev.bus_id,
+		  reg_read(ohci, OHCI1394_HCControlSet) &
+		  OHCI1394_HCControl_noByteSwapData ?
+			"implements" : "does not support");
+
 	reg_write(ohci, OHCI1394_HCControlClear,
 		  OHCI1394_HCControl_noByteSwapData);
 
-- 
Stefan Richter
-=====-==--- -=== =----
http://arcgraph.de/sr/


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