diff options
author | Doug Anderson <dianders@chromium.org> | 2014-04-30 13:44:07 -0400 |
---|---|---|
committer | Lee Jones <lee.jones@linaro.org> | 2014-06-03 03:11:48 -0400 |
commit | 9c0b54a120348813de16be935d2e8a3e0e8e4a8b (patch) | |
tree | 1973af48d563e00de799a59f41ebe94a69b90979 /drivers/mfd | |
parent | c9a81d67ce4c9cd9b73f8ec6dba827882555d47e (diff) |
mfd: cros_ec: spi: Increase cros_ec_spi deadline from 5ms to 100ms
We're adding i2c tunneling to the list of things that goes over
cros_ec. i2c tunneling can be slooooooow, so increase our deadline to
100ms to account for that.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Andrew Bresticker <abrestic@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Diffstat (limited to 'drivers/mfd')
-rw-r--r-- | drivers/mfd/cros_ec_spi.c | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index 4f863c346547..0b8d32829166 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c | |||
@@ -39,14 +39,22 @@ | |||
39 | #define EC_MSG_PREAMBLE_COUNT 32 | 39 | #define EC_MSG_PREAMBLE_COUNT 32 |
40 | 40 | ||
41 | /* | 41 | /* |
42 | * We must get a response from the EC in 5ms. This is a very long | 42 | * Allow for a long time for the EC to respond. We support i2c |
43 | * time, but the flash write command can take 2-3ms. The EC command | 43 | * tunneling and support fairly long messages for the tunnel (249 |
44 | * processing is currently not very fast (about 500us). We could | 44 | * bytes long at the moment). If we're talking to a 100 kHz device |
45 | * look at speeding this up and making the flash write command a | 45 | * on the other end and need to transfer ~256 bytes, then we need: |
46 | * 'slow' command, requiring a GET_STATUS wait loop, like flash | 46 | * 10 us/bit * ~10 bits/byte * ~256 bytes = ~25ms |
47 | * erase. | 47 | * |
48 | */ | 48 | * We'll wait 4 times that to handle clock stretching and other |
49 | #define EC_MSG_DEADLINE_MS 5 | 49 | * paranoia. |
50 | * | ||
51 | * It's pretty unlikely that we'll really see a 249 byte tunnel in | ||
52 | * anything other than testing. If this was more common we might | ||
53 | * consider having slow commands like this require a GET_STATUS | ||
54 | * wait loop. The 'flash write' command would be another candidate | ||
55 | * for this, clocking in at 2-3ms. | ||
56 | */ | ||
57 | #define EC_MSG_DEADLINE_MS 100 | ||
50 | 58 | ||
51 | /* | 59 | /* |
52 | * Time between raising the SPI chip select (for the end of a | 60 | * Time between raising the SPI chip select (for the end of a |