On Sat, Apr 16, 2016 at 08:08:50AM +0000, Shardar Mohammed wrote: > Thanks for the review, updated with comments inline with Shardar. > > > On Fri, Apr 15, 2016 at 06:51:47PM +0530, Shardar Shariff Md wrote: > > > From: Shardar Shariff Md <smohammed@xxxxxxxxxx> > > > > > > To summarize the issue observed in error cases: > > > > > > In SW: For i2c message transfer, packet header and data payload is > > > posted and then required error/packet completion interrupts are > > > enabled later. > > > > > > In HW flow: HW process the packet just after packet header is posted, > > > if ARB lost/NACK error occurs (SW will not handle immediately when > > > error happens as error interrupts are not enabled at this point). HW > > > assumes error is acknowledged and clears current data in FIFO, But SW > > > here posts the remaining data payload which still stays in FIFO as > > > stale data (data without packet header). > > > > > > Now once the interrupts are enabled, SW handles ARB lost/NACK error by > > > clearing the ARB lost/NACK interrupt. Now HW assumes that SW attended > > > the error and will parse/process stale data (data without packet > > > header) present in FIFO which causes invalid NACK errors. > > > > > > Fix: Enable the error interrupts before posting the packet into FIFO > > > which make sure HW to not clear the fifo. Also disable the packet mode > > > before acknowledging errors (ARB lost/NACK error) to not process any > > > stale data. > > > > > > As error interrupts are enabled before posting the packet header use > > > spinlock to avoid preempting. > > > > Please try to use up the full 78 characters per line in the commit message > > (with the exception being the subject line that should be shorter). > > [Shardar] Will take care of this. I just realized my comment was wrong. The rule is to use 72 characters per line for the commit message. Sorry about that. Thierry
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