Hi,

On Tue, Aug 30, 2016 at 07:43:29PM +0800, Shawn Guo wrote:

On Mon, Aug 29, 2016 at 11:06:44AM -0500, Zhi Li wrote:

quoted

On Wed, Aug 17, 2016 at 2:42 PM, Zhengyu Shen [off-list ref] wrote:

quoted

MMDC is a multi-mode DDR controller that supports DDR3/DDR3L x16/x32/x64
and LPDDR2 two channel x16/x32 memory types. MMDC is configurable, high
performance, and optimized. MMDC is present on i.MX6 Quad and i.MX6
QuadPlus devices, but this driver only supports i.MX6 Quad at the moment.
MMDC provides registers for performance counters which read via this
driver to help debug memory throughput and similar issues.

$ perf stat -a -e mmdc/busy-cycles/,mmdc/read-accesses/,mmdc/read-bytes/,mmdc/total-cycles/,mmdc/write-accesses/,mmdc/write-bytes/ dd if=/dev/zero of=/dev/null bs=1M count=5000
Performance counter stats for 'dd if=/dev/zero of=/dev/null bs=1M count=5000':

         898021787      mmdc/busy-cycles/
          14819600      mmdc/read-accesses/
            471.30 MB   mmdc/read-bytes/
        2815419216      mmdc/total-cycles/
          13367354      mmdc/write-accesses/
            427.76 MB   mmdc/write-bytes/

       5.334757334 seconds time elapsed

Signed-off-by: Zhengyu Shen <redacted>
Signed-off-by: Frank Li <frank.li@nxp.com>

Shawn Guo:

         No new comments got more than 1 weeks.
         Did you plan accept it?

@Mark, how do you think of this version?

Sorry, I've been away for the last week and haven't had the chance to
look at this yet. I will try to get round to it in the next few days.

In the meantime, could you please try attacking this with Vince's perf
fuzzer [1] (as root, or with perf_event_paranoid dropped to -1)? It's
rather good at finding (subtle) issues in drivers.

Thanks,
Mark.

[1] https://github.com/deater/perf_event_tests