On 10/3/2014 2:34 PM, Stephen Boyd wrote: > Hi Frank, > > On 08/13/14 19:42, Frank Rowand wrote: >> On 8/13/2014 7:33 PM, Frank Rowand wrote: >>> On 8/12/2014 5:23 PM, Stephen Boyd wrote: >>>> On 08/06/14 17:16, Frank Rowand wrote: >> < snip > >> >>> The patches you sent are a little hard to read since they modify further code >>> that my patch modified. So I have redone your patches, as if my patch was >>> not previously applied. Hopefully I did not make any mistakes there. I will >>> reply to this email with each of your redone patches. >> Stephen's patch alternative number 2: > > I had a discussion with the hardware engineer. Apparently the break bit > in the SR register is not "sticky" so it doesn't always stay set when > the handle_rx_dm() function runs and a break has entered the fifo. I > used your debug patches to confirm this (I never see the break status > bit when the fifo has multiple characters in it). It sounds like this > bit can't really be used reliably. The recommendation is to use either > the break start or break stop interrupt to detect when a break has > occurred and then search the fifo for the break character (an all zero > character). If there are two such characters then we can't be certain > when the break was, but the chances of this seem really slim considering > that the stale timeout probably triggers first before a human can type a > character after the break. That sounds good to me. > On 1.4 hardware we can change the mode to be single character and then > we can reliably detect the break character because only one character > enters the fifo and the higher bits of the fifo can be used to detect if > it is a break or not. Making that change is probably not that hard, I > believe we can reuse all the handle_rx_dm logic and force single > character mode on consoles, but 1.3 hardware doesn't benefit from this > change. I'll try to get something together soon that tries to make this > all work as best as it can. Thanks! I'll be glad to review and test. And whatever else I can do to help. -Frank -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
