On Wed, 25 Nov 2015, Ondrej Zary wrote:
On Wednesday 25 November 2015, Finn Thain wrote:
On Tue, 24 Nov 2015, Ondrej Zary wrote:
Instead of fixing split transfers, simply forced everything
non-modulo-128 to PIO:
[...]
I don't have any reason to think that your card will allow part of
a transfer to be performed with PDMA and the rest with PIO. So I don't
really object to the patch.
From looking at the datasheet, I think your patch is correct.
Your patch needs to be applied after mine, so if you will sign-off, I'll
include it in the series with your Signed-off-by and "From:" header.
But I don't understand the need for it either: I have no idea what
state the driver, chip and scsi bus were in when the 126-byte PIO
transfer failed. If the PIO transfer didn't succeed then the entire
command should have failed.
The patch was just a quick hack to confirm that PDMA is not completely
broken.
Now we know that it mostly works so I can investigate the partial PIO
problem.
There may not be any problem to investigate. Because this 53C80 core is
embedded in other logic, it's hard to say whether or not the partial PIO
algorithm could be expected to work at all.
Besides, the DMA errata don't apply to this core. And large transfers will
always be divisible by 128 bytes so there's very little to be gained.
[...]
53C400A datasheet would be great too but haven't found any.
I don't have one either.
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