diff options
Diffstat (limited to 'kernels/linux-libre-pae/0001-e1000e-Fix-tight-loop-implementation-of-systime-read.patch')
| -rw-r--r-- | kernels/linux-libre-pae/0001-e1000e-Fix-tight-loop-implementation-of-systime-read.patch | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/kernels/linux-libre-pae/0001-e1000e-Fix-tight-loop-implementation-of-systime-read.patch b/kernels/linux-libre-pae/0001-e1000e-Fix-tight-loop-implementation-of-systime-read.patch new file mode 100644 index 000000000..0bea7fe08 --- /dev/null +++ b/kernels/linux-libre-pae/0001-e1000e-Fix-tight-loop-implementation-of-systime-read.patch @@ -0,0 +1,65 @@ +From 37b12910dd11d9ab969f2c310dc9160b7f3e3405 Mon Sep 17 00:00:00 2001 +From: Raanan Avargil <raanan.avargil@intel.com> +Date: Sun, 19 Jul 2015 16:33:20 +0300 +Subject: [PATCH] e1000e: Fix tight loop implementation of systime read + algorithm + +Change the algorithm. Read systimel twice and check for overflow. +If there was no overflow, use the first value. +If there was an overflow, read systimeh again and use the second +systimel value. + +Signed-off-by: Raanan Avargil <raanan.avargil@intel.com> +Tested-by: Aaron Brown <aaron.f.brown@intel.com> +Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> +--- + drivers/net/ethernet/intel/e1000e/netdev.c | 31 ++++++++++++++++++++---------- + 1 file changed, 21 insertions(+), 10 deletions(-) + +diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c +index 24b7269..96a8166 100644 +--- a/drivers/net/ethernet/intel/e1000e/netdev.c ++++ b/drivers/net/ethernet/intel/e1000e/netdev.c +@@ -4280,18 +4280,29 @@ static cycle_t e1000e_cyclecounter_read(const struct cyclecounter *cc) + struct e1000_adapter *adapter = container_of(cc, struct e1000_adapter, + cc); + struct e1000_hw *hw = &adapter->hw; ++ u32 systimel_1, systimel_2, systimeh; + cycle_t systim, systim_next; +- /* SYSTIMH latching upon SYSTIML read does not work well. To fix that +- * we don't want to allow overflow of SYSTIML and a change to SYSTIMH +- * to occur between reads, so if we read a vale close to overflow, we +- * wait for overflow to occur and read both registers when its safe. ++ /* SYSTIMH latching upon SYSTIML read does not work well. ++ * This means that if SYSTIML overflows after we read it but before ++ * we read SYSTIMH, the value of SYSTIMH has been incremented and we ++ * will experience a huge non linear increment in the systime value ++ * to fix that we test for overflow and if true, we re-read systime. + */ +- u32 systim_overflow_latch_fix = 0x3FFFFFFF; +- +- do { +- systim = (cycle_t)er32(SYSTIML); +- } while (systim > systim_overflow_latch_fix); +- systim |= (cycle_t)er32(SYSTIMH) << 32; ++ systimel_1 = er32(SYSTIML); ++ systimeh = er32(SYSTIMH); ++ systimel_2 = er32(SYSTIML); ++ /* Check for overflow. If there was no overflow, use the values */ ++ if (systimel_1 < systimel_2) { ++ systim = (cycle_t)systimel_1; ++ systim |= (cycle_t)systimeh << 32; ++ } else { ++ /* There was an overflow, read again SYSTIMH, and use ++ * systimel_2 ++ */ ++ systimeh = er32(SYSTIMH); ++ systim = (cycle_t)systimel_2; ++ systim |= (cycle_t)systimeh << 32; ++ } + + if ((hw->mac.type == e1000_82574) || (hw->mac.type == e1000_82583)) { + u64 incvalue, time_delta, rem, temp; +-- +2.5.1 + |