Re: [bluetooth] linux-3.x regression (bisected)

From: Rene Herman
Date: Wed Dec 28 2011 - 17:17:33 EST

On 28-12-11 17:48, Marcel Holtmann wrote:

< HCI Command: Read Local Extended Features (0x04|0x0004) plen 1
page 1
> HCI Event: Command Complete (0x0e) plen 14
Read Local Extended Features (0x04|0x0004) ncmd 1
status 0x00 page 0 max 0
Features: 0xff 0xfe 0xff 0x7e 0x98 0x19 0x00 0x80

And this is correct. Page 0 is the same as local features. Storing this
as page 1 is the issue here. We request page 1, but we are getting page
0 instead. So yes, the controller is broken, but not as broken as it
gets us false information.

By the way, while the bluetooth (2.0) spec seems to consist of a 1230 page document that I am most certainly not going to study ...

... I couldn't help noticing that the HCI_Read_Local_Extended_Features command is in fact specified to return "The highest features page number which contains non-zero bits for the local device", and if I look at the above, it seems to indeed return max=0.

Is it as such not in fact the case that the dongle is spec-compliant, whereas it's the linux code that neglects to check that return value in order to make sure that it requested a valid page?

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