Re: Radeon regression fix

From: Brad Campbell
Date: Fri Sep 30 2011 - 01:15:39 EST


On 30/09/11 12:59, Alex Deucher wrote:
On Thu, Sep 29, 2011 at 8:23 PM, Brad Campbell

Looking at it with a nights sleep, it's obvious the code path in
aux_native_write is ok. Is this a bit cleaner than the last patch?

Looks pretty good. I was thinking of something more like this (sorry
for the lack of a patch, I'm away from my source trees at the moment):

while (1) {
ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
msg, msg_bytes, recv, recv_bytes, delay,&ack);

if (ret< 0)
return ret;
if ((ack& AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_ACK)
return ret;
else if ((ack& AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
udelay(400);
else if (ret == 0)
return -EPROTO;
else
return -EIO;
}

Yep, that looks cleaner.

My only thought was the pre-3.0 code had a limit to the number of retries. Was that for a specific reason or is it ok to attempt to retry indefinitely if we receive a DEFER ?


Thanks for tracking this down.

No worries. I learned quite a bit about some kernel internals and more than a few quirks about apple hardware while muddling around.
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