On Thu, May 17, 2018 at 1:22 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: > On 05/17/2018 06:20 PM, Frank Mori Hess wrote: > The problem is not so much on the software side but even more so on the > hardware side. Not all hardware even supports aborting a transfer with no > data loss because there is no precise measurement of how much data has been > transferred. The residue that is reported is always the lower bound, this > much has been transferred but it might actually have been more. I'd just like to point out, if the pl330 driver actually did report a upper bound on the residue (lower bound on bytes transferred) that would also blow up Marek's samsung serial driver use case. Instead of being in a situation where data loss might occur rarely due to a race condition, they would be in a situation where data loss occurs every time they stop a transfer. Not that such a residue reporting would be incorrect though, the pl330 driver doesn't even advertise burst level granularity with its residue reporting. -- 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
