On 6/11/19 5:29 AM, Srinivas Kandagatla wrote:
On 10/06/2019 15:12, Pierre-Louis Bossart wrote:
+ if (dev_addr == SDW_BROADCAST_DEV_NUM) { + ctrl->fifo_status = 0; + ret = wait_for_completion_timeout(&ctrl->sp_cmd_comp, + msecs_to_jiffies(TIMEOUT_MS));
This is odd. The SoundWire spec does not handle writes to a single device or broadcast writes differently. I don't see a clear reason why you would only timeout for a broadcast write.
There is danger of blocking here without timeout.
Right, and it's fine to add a timeout. The question is why add a timeout *only* for a broadcast operation? It should be added for every transaction IMO, unless you have a reason not to do so.
I did try this before, the issue is when we read/write registers from interrupt handler, these can be deadlocked as we will be interrupt handler waiting for another completion interrupt, which will never happen unless we return from the first interrupt.
I don't quite get the issue. With the Intel hardware we only deal with Master registers (some of which mirror the bus state) in the handler and will only modify Slave registers in the thread. All changes to Slave registers will be subject to a timeout as well as a check for no response or NAK. Not sure what is specific about your solution that requires a different handling of commands depending on which device number is used. It could very well be that you've uncovered a flaw in the bus design but I still don't see how it would be Qualcomm-specific?