diff options
| author | Angel Pons <th3fanbus@gmail.com> | 2021-01-12 01:21:24 +0100 |
|---|---|---|
| committer | Patrick Georgi <pgeorgi@google.com> | 2021-01-15 11:24:41 +0000 |
| commit | 7519ca42b53201083ec763058dadd8fdb2050f80 (patch) | |
| tree | bc27bbc90f5379c894cd9b797458dcf42e325d09 /src/northbridge/intel/sandybridge | |
| parent | 0a7d99c089eea04ec03958f96dd180bffa6fcc4a (diff) | |
nb/intel/sandybridge: Clarify command timing calculation
Command timing is the absolute value of the most negative `pi_coding`
value across all ranks, or zero if there are no negative values. Use the
MAX() macro to ease proving that `cmd_delay` can never be negative, and
then drop the always-false underflow check.
The variable type for `cmd_delay` still needs to be signed because of
the comparisons with `pi_coding`, which is a signed value. Using an
unsigned type would result in undefined and also undesired behavior.
Change-Id: I714d3cf57d0f62376a1107af63bcd761f952bc3a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49320
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Diffstat (limited to 'src/northbridge/intel/sandybridge')
| -rw-r--r-- | src/northbridge/intel/sandybridge/raminit_common.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/src/northbridge/intel/sandybridge/raminit_common.c b/src/northbridge/intel/sandybridge/raminit_common.c index f766867965..cef01316dc 100644 --- a/src/northbridge/intel/sandybridge/raminit_common.c +++ b/src/northbridge/intel/sandybridge/raminit_common.c @@ -938,16 +938,11 @@ void program_timings(ramctr_timing *ctrl, int channel) u32 clk_logic_dly = 0; /* - * Apply command delay if desired setting is negative. Find the - * most negative value: 'cmd_delay' will be the absolute value. + * Compute command timing as abs() of the most negative PI code + * across all ranks. Use zero if none of the values is negative. */ FOR_ALL_POPULATED_RANKS { - if (cmd_delay < -ctrl->timings[channel][slotrank].pi_coding) - cmd_delay = -ctrl->timings[channel][slotrank].pi_coding; - } - if (cmd_delay < 0) { - printk(BIOS_ERR, "C%d command delay underflow: %d\n", channel, cmd_delay); - cmd_delay = 0; + cmd_delay = MAX(cmd_delay, -ctrl->timings[channel][slotrank].pi_coding); } if (cmd_delay > CCC_MAX_PI) { printk(BIOS_ERR, "C%d command delay overflow: %d\n", channel, cmd_delay); |