| Message ID | 1467049167-14628-4-git-send-email-dianders@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Monday 27 June 2016 11:09 PM, Douglas Anderson wrote: > Two times out of 2000 reboots I ran into the error message > "rockchip_emmc_phy_power: dllrdy timeout". Presumably there is some > corner case where the DLL just takes a little longer to timeout. Let's > give it even more time to handle these corner cases. > > Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Kishon Vijay Abraham I <kishon@ti.com> > --- > drivers/phy/phy-rockchip-emmc.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/phy/phy-rockchip-emmc.c b/drivers/phy/phy-rockchip-emmc.c > index a2aa6aca7dec..fd57345ffed2 100644 > --- a/drivers/phy/phy-rockchip-emmc.c > +++ b/drivers/phy/phy-rockchip-emmc.c > @@ -206,8 +206,18 @@ static int rockchip_emmc_phy_power(struct phy *phy, bool on_off) > * per the math: 10.2 us * (50000000 Hz / 100000 Hz) => 5.1 ms > * Hopefully we won't be running at 100 kHz, but we should still make > * sure we wait long enough. > + * > + * NOTE: There appear to be corner cases where the DLL seems to take > + * extra long to lock for reasons that aren't understood. In some > + * extreme cases we've seen it take up to over 10ms (!). We'll be > + * generous and give it 50ms. We still busy wait here because: > + * - In most cases it should be super fast. > + * - This is not called lots during normal operation so it shouldn't > + * be a power or performance problem to busy wait. We expect it > + * only at boot / resume. In both cases, eMMC is probably on the > + * critical path so busy waiting a little extra time should be OK. > */ > - timeout = jiffies + msecs_to_jiffies(10); > + timeout = jiffies + msecs_to_jiffies(50); > do { > udelay(1); > >
diff --git a/drivers/phy/phy-rockchip-emmc.c b/drivers/phy/phy-rockchip-emmc.c index a2aa6aca7dec..fd57345ffed2 100644 --- a/drivers/phy/phy-rockchip-emmc.c +++ b/drivers/phy/phy-rockchip-emmc.c @@ -206,8 +206,18 @@ static int rockchip_emmc_phy_power(struct phy *phy, bool on_off) * per the math: 10.2 us * (50000000 Hz / 100000 Hz) => 5.1 ms * Hopefully we won't be running at 100 kHz, but we should still make * sure we wait long enough. + * + * NOTE: There appear to be corner cases where the DLL seems to take + * extra long to lock for reasons that aren't understood. In some + * extreme cases we've seen it take up to over 10ms (!). We'll be + * generous and give it 50ms. We still busy wait here because: + * - In most cases it should be super fast. + * - This is not called lots during normal operation so it shouldn't + * be a power or performance problem to busy wait. We expect it + * only at boot / resume. In both cases, eMMC is probably on the + * critical path so busy waiting a little extra time should be OK. */ - timeout = jiffies + msecs_to_jiffies(10); + timeout = jiffies + msecs_to_jiffies(50); do { udelay(1);
Two times out of 2000 reboots I ran into the error message "rockchip_emmc_phy_power: dllrdy timeout". Presumably there is some corner case where the DLL just takes a little longer to timeout. Let's give it even more time to handle these corner cases. Signed-off-by: Douglas Anderson <dianders@chromium.org> --- drivers/phy/phy-rockchip-emmc.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)