The memory clock-rate change could be running on a non-boot CPU, while the
boot CPU handles the EMC interrupt. This introduces an unnecessary latency
since boot CPU should handle the interrupt and then notify the sibling CPU
about clock-rate change completion. In some rare cases boot CPU could be
in uninterruptible state for a significant time (like in a case of KASAN +
NFS root), it could get to the point that completion timeouts before boot
CPU gets a chance to handle interrupt. The solution is to get rid of the
completion and replace it with interrupt-status polling.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Replace the symbolic permissions with octals in order to make them
readable.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Correctly set clk rate-range if number of available timings is zero.
This fixes noisy "invalid range [4294967295, 0]" error messages during
boot.
Fixes: 8cee32b400 ("memory: tegra: Implement EMC debugfs interface on Tegra30")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The code waits for auto calibration to be finished and not to be disabled.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Previously there was a problem where a late handshake handling caused
a memory corruption, this problem was resolved by issuing calibration
command right after changing the timing, but looks like the solution
wasn't entirely correct since calibration interval could be disabled as
well. Now programming sequence is completed immediately after receiving
handshake from CaR, without potentially long delays and in accordance to
the TRM's programming guide.
Secondly, the TRM's programming guide suggests to flush EMC writes by
reading any *MC* register before doing CaR changes. This is also addressed
now.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The current code doesn't prevent race conditions of suspend/resume vs CCF.
Let's take exclusive control over the EMC clock during suspend in a way
that is free from race conditions.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
A common debugfs interface is already available on Tegra20, Tegra124,
Tegra186 and Tegra194. Implement the same interface on Tegra30 to enable
testing of the EMC frequency scaling code using a unified interface.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Trying to suspend driver results in a crash if timings aren't available in
device-tree.
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Fixes: e34212c75a ("memory: tegra: Introduce Tegra30 EMC driver")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Introduce driver for the External Memory Controller (EMC) found on Tegra30
chips, it controls the external DRAM on the board. The purpose of this
driver is to program memory timing for external memory on the EMC clock
rate change.
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
