diff options
Diffstat (limited to 'drivers/phy')
| -rw-r--r-- | drivers/phy/phy-rockchip-emmc.c | 12 |
1 files changed, 11 insertions, 1 deletions
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); |