On Thu, Aug 04, 2016 at 05:59:30PM +0200, Lars-Peter Clausen wrote: > On 08/04/2016 05:38 PM, Russell King - ARM Linux wrote: > [...] > > What you instead need to do is to find some way to record in your > > driver that transaction 2 failed, and when dma_cookie_status() says > > that a transaction has DMA_COMPLETE status, you need to look up to > > see whether it failed. > > In my opinion this is where the current API is broken by design. For each > transfer that fails you need to store the cookie associated with that > transfer in some kind of lookup table. Since there is no lifetime associated > with a cookie entries in this table would need to be retained forever and it > will grow unbound. And how many drivers can report errors? And how many drivers can guarantee DMA_COMPLETE implies transaction was succesful. > Ideally we'd mark error reporting through this interface as deprecated and > discourage new users of the interface. As far as I can see most of the few > drivers that do return DMA_ERROR get it wrong anyway, e.g. return it > unconditionally for all cookies when an error occurred for any of them. Error reporting is quite tricky as detection is a problem. So yes if you can do so, it is highly encouraged to report using new interface which is better than client checking after callback. Btw what is the behaviour after error? I would think that client will see an error and report to upper layer while initiaite closure of transaction. So does driver need to keep the state for a longer time :-) -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
