On 10/29/2012 10:18 AM, Laxman Dewangan wrote: > On Monday 29 October 2012 08:47 PM, Stephen Warren wrote: >> On 10/26/2012 12:49 PM, Laxman Dewangan wrote: >>>> >>>> Why not just always set SLINK_FIFO_ERROR; does it have to be set in the >>>> write only if the status was previously asserted? If that is true, how >>>> do you avoid a race condition where the bit gets set in SLINK_STATUS >>>> after you read it but before you write to clear it? >>> Status gets updated together. There is no steps of updating status. >> Sorry, I don't understand this answer. > > The status should be updated once by HW and so there is no race condition. > HW behavior is that if the tx or Rx error occurs, it updates the status, > generates interrupt and still continue transfer and later on, it > generates the ready. > In first isr, we read status, error status found and so in isr thread, > we reset controller to stop the transfer. > > So in good state, only ready bit will be set and hence writing 1 to > clear it. > In error state, clearing error first in ISR and in isr thread resetting > the controller to stop the controller engine. OK, I see why there's no race. It still seems simply to me if tegra_slink_clear_status() just always writes all the status bits, but I suppose it isn't a correctness issue. >>> Is there a way to support the reset of controller. We will need this >>> functionality. >> >> Why do we need to reset the controller at all; can't we simply program >> all the (few) configuration registers? Are there HW bugs that hang the >> controller and require a reset or something? > > HW generates error, then interrupt and still continue transfer and > later point of time it generates the transfer done. > We want to stop the transfer once error get detected. For this we need > to reset controller. > I did disabling rx and tx but still controller shows as busy. Oh dear. Well, I guess it'll have to be OK then; we'll just have to find a way of decoupling this API from the mach-tegra directory later:-( -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
