Re: Radeon regression fix

[Brad Campbell <lists2009@fnarfbargle.com>]

On 29/09/11 23:21, Brad Campbell wrote:
> On 29/09/11 22:36, Alex Deucher wrote:
>> On Thu, Sep 29, 2011 at 10:21 AM, Brad Campbell<brad@fnarfbargle.com>
>> wrote:
>>> This patch fixes a regression introduced between 2.6.39& 3.1-rc1 whereby
>>> the displayport AUX channel stopped re-trying commands that elicited
>>> a DEFER
>>> response.
>>>
>>
>> It should still be retrying, just restructured slightly. The retry
>> logic just moved into radeon_dp_i2c_aux_ch(),
>> radeon_dp_aux_native_write(), and radeon_dp_aux_native_read(), e.g.,
>>
>> else if ((ack& AUX_NATIVE_REPLY_MASK) == AUX_NATIVE_REPLY_DEFER)
>> udelay(400);
>>
>> Perhaps the delay is causing a problem. Does removing the udelay(400);
>> help?

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?

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c 
b/drivers/gpu/drm/radeon/atombios_dp.c
index 7ad43c6..aacc97d 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -158,14 +158,17 @@ static int radeon_dp_aux_native_read(struct 
radeon_connector *radeon_connector,
         while (1) {
                 ret = radeon_process_aux_ch(dig_connector->dp_i2c_bus,
                                             msg, msg_bytes, recv, 
recv_bytes, delay, &ack);
-               if (ret == 0)
+               if (ret == 0){
+                       if ((ack & AUX_NATIVE_REPLY_MASK) == 
AUX_NATIVE_REPLY_DEFER){
+                               udelay(400);
+                               continue;
+                       }
                         return -EPROTO;
+               }
                 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
                         return -EIO;
         }