Re: Radeon regression fix
From: Alex Deucher
Date: Fri Sep 30 2011 - 01:39:35 EST
On Fri, Sep 30, 2011 at 1:14 AM, Brad Campbell
<lists2009@xxxxxxxxxxxxxxx> wrote:
> 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 ?
I need to double check the DP spec, but I think it's 4. The while (1)
loops in radeon_dp_aux_native_write() and radeon_dp_aux_native_read()
should probably be changed to:
for (retry = 0; retry < 4; retry++)
to match what we do in radeon_dp_i2c_aux_ch().
Alex
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