memory: tegra: Fix integer overflow on tick value calculation

BugLink: https://bugs.launchpad.net/bugs/1838576
commit b906c056b6023c390f18347169071193fda57dde upstream.

Multiplying the Memory Controller clock rate by the tick count results
in an integer overflow and in result the truncated tick value is being
programmed into hardware, such that the GR3D memory client performance is
reduced by two times.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
index 1d49a8dd4a374df623a7bfdddda4874ddeaf47ee..7c040a3b45be2df2f8bbab0cddc6738a5aa46fc7 100644 (file)
--- a/drivers/memory/tegra/mc.c
+++ b/drivers/memory/tegra/mc.c
@@ -72,7 +72,7 @@ static int tegra_mc_setup_latency_allowance(struct tegra_mc *mc)
        u32 value;
 
        /* compute the number of MC clock cycles per tick */
-       tick = mc->tick * clk_get_rate(mc->clk);
+       tick = (unsigned long long)mc->tick * clk_get_rate(mc->clk);
        do_div(tick, NSEC_PER_SEC);
 
        value = readl(mc->regs + MC_EMEM_ARB_CFG);