[eepro100] 82559 Rx DMA burst limiting.

Robin Kletke robink@atvideo.com
Wed, 24 Oct 2001 08:08:41 -0700


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Could someone please give me the correct settings for limiting the 82559 =
as PCI Master when doing DMA burst writes into processor memory?  I am =
attempting to run on an ARM7 variant (custom ASIC), that is giving a PCI =
target-disconnect during the 82559 burst write (CBE =3D 0111).  In these =
cases, the 82559 attempts to burst a large number of 32 bit words to the =
ARM, but the ARM asserts TRDY and STOP (target-disconnect).  The 82559 =
eventually does disconnect, but the final 32 bit word of the burst is =
lost and not written to local ARM memory.  I suspect that there is a =
problem with the ARM ASIC PCI/local bus bridge, but need to fix this in =
another way.

My hope was to limit the burst size of the 82559 to 4 or 5 32 bit words. =
However, after setting rxdmacount and txdmacount to various values, =
(4,4) (4,0x84), I don't see any change in the 82559 cycles.

What is required to set and enable the dma counters?  Does byte 5, bit 7 =
=3D=3D 1 enable or disable?  Various versions of the various drivers =
seem to contradict themselves.

Thanks for the help

Robin Kletke
Superior Software, Inc.
robink@ssinw.com


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Could someone please give me the correct settings = for limiting=20 the 82559 as PCI Master when doing DMA burst writes into processor = memory? =20 I am attempting to run on an ARM7 variant (custom ASIC), that is giving = a PCI=20 target-disconnect during the 82559 burst write (CBE =3D 0111).  In = these=20 cases, the 82559 attempts to burst a large number of 32 bit words to the = ARM,=20 but the ARM asserts TRDY and STOP (target-disconnect).  The 82559=20 eventually does disconnect, but the final 32 bit word of the burst is = lost and=20 not written to local ARM memory.  I suspect that there is a problem = with=20 the ARM ASIC PCI/local bus bridge, but need to fix this in another=20 way.
 
My hope was to limit the burst size of the 82559 to = 4 or 5 32=20 bit words. However, after setting rxdmacount and txdmacount to various = values,=20 (4,4) (4,0x84), I don't see any change in the 82559 cycles.
 
What is required to set and enable the dma = counters? =20 Does byte 5, bit 7 =3D=3D 1 enable or disable?  Various versions of = the various=20 drivers seem to contradict themselves.
 
Thanks for the help
 
Robin Kletke
Superior Software, Inc.
robink@ssinw.com
 
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