On 03/08/2012 05:26 AM, jerome huang wrote:
I found a interesting thing. Here is my original test steps: 1. plugin 8192 => at this step, modules will be inserted 2. ifconfig wlan0 up => at this step, firmware will be uploaded 3. iwlist wlan0 scanning => check if wlan0 works The original problem occurs at last step, there is "always" no ap list result. And I found a way to make it work "always": 1. plugin 8192 2. ifconfig wlan0 up 3. ifconfig wlan0 down 4. ifconfig wlan0 up 5. iwlist wlan0 scanning If I up->down->up sequentially, (without scanning after first up), and then scanning(step 5), it works! Does this mean the firmware is not transfered or written correctly?
I did a bit of testing with debug level 4. For kernels 3.2 and older, the firmware file is read by the kernel when the driver is loaded using the synchronous method. I confirm that it is not loaded into the device until the interface is brought up. The upload mechanism is supposed to be waiting while the firmware is uploaded, but that may not be happening.
When you did the original 3-step process, was there any delay between steps 2 and 3? Does anything change if you wait for 30 sec between steps 2 and 3?
with kernels 3.3 and later, there is a major change in the firmware loading in that an asynchronous method is used. The probe routine run when the driver is loaded places a firmware read request, but does not wait. The interface startup is delayed until the callback routine is entered. This change will not affect when the firmware is loaded into the device.
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