On Fri, Jan 13, 2017 at 06:00:44AM +0000, Appana Durga Kedareswara Rao wrote: > Hi Vinod, > > Thanks for the review... > > [Snip] > > > > > > > On Sat, Jan 07, 2017 at 12:15:30PM +0530, Kedareswara rao Appana wrote: > > > > > When driver is handling AXI DMA SoftIP When user submits multiple > > > > > descriptors back to back on the S2MM(recv) side with the current > > > > > driver flow the last buffer descriptor next bd points to a invalid > > > > > location resulting the invalid data or errors in the DMA engine. > > > > > > > > Can you rephrase this, it a bit hard to understand. > > > > > > When DMA is receiving packets h/w expects the descriptors Should be in > > > the form of a ring (I mean h/w buffer descriptor Next descriptor field > > > should always point to valid address So that when DMA engine go and > > > fetch that next descriptor it always Sees a valid address). > > > > > > > > > But with the current driver implementation when user queues Multiple > > > descriptors the last descriptor next descriptor field Pointing to an > > > invalid location causing data corruption or Errors from the DMA h/w > > > engine... > > > > > > To avoid this issue creating a Buffer descriptor Chain during Channel > > > allocation and using those buffer descriptors for processing User > > > requested data. > > > > Is it not doable to to modify the next pointer to point to subsequent transaction. > > IOW you are modifying tail descriptor to point to subsequent descriptor. > > > > Btw how and when does DMA stop, assuming it is circular it never would, isn't > > there a valid/stop flag associated with a descriptor which tells DMA engine what > > to do next > > There are two registers that controls the DMA transfers. > Current descriptor and tail descriptor register. > When current descriptor reaches tail descriptor dma engine will pause. > > When reprogramming the tail descriptor the DMA engine will starts fetching descriptors again. > > But with the existing driver flow if we reprogram the tail descriptor > The tail descriptor next descriptor field is pointing to an invalid location > Causing data corruption... So the solution is..? > > Btw there is something wrong with your MUA perhaps line are titlecased for no > > reason. This is typically behavious of non linux tool which may not be great tool > > for this work. > > Thanks for pointing it out. > I usually replies from outlook from a windows machine. > Will check with others in my team how they configured their mail client. Yeah that isnt right tool for the job. See Documentation/process/email-clients.rst FWIW, I use mutt, vim as editor with exchange servers, seems to work well for me now. -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
