From mboxrd@z Thu Jan 1 00:00:00 1970 From: YeeLi Date: Tue, 29 Jun 2021 16:21:28 +0800 Subject: [Intel-wired-lan] [PATCH] driver core: fix e1000e ltr bug Message-ID: <20210629082128.255988-1-seven.yi.lee@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: In e1000e driver, a PCIe-like device, the max snoop/no-snoop latency is the upper limit.So, directly compare the size of lat_enc and max_ltr_enc is incorrect. In 1000Mbps, 0x8b9 < 0x1003, 189440 ns < 3145728 ns, correct. In 100Mbps, 0xc3a < 0x1003, 1900544 ns < 3145728 ns, correct. In 10Mbps, 0xe40 < 0x1003, 18874368 > 3145728, incorrect. Decoded the lat_enc and max_ltr_enc before compare them is necessary. Signed-off-by: YeeLi --- drivers/net/ethernet/intel/e1000e/ich8lan.c | 23 ++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c index 590ad110d383..3bff1b570b76 100644 --- a/drivers/net/ethernet/intel/e1000e/ich8lan.c +++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c @@ -986,6 +986,27 @@ static s32 e1000_k1_workaround_lpt_lp(struct e1000_hw *hw, bool link) return ret_val; } +static u32 convert_e1000e_ltr_scale(u32 val) +{ + if (val > 5) + return 0; + + return 1U << (5 * val); +} + +static u64 decoded_ltr(u32 val) +{ + u64 decoded_latency; + u32 value; + u32 scale; + + value = val & 0x03FF; + scale = (val & 0x1C00) >> 10; + decoded_latency = value * convert_e1000e_ltr_scale(scale); + + return decoded_latency; +} + /** * e1000_platform_pm_pch_lpt - Set platform power management values * @hw: pointer to the HW structure @@ -1059,7 +1080,7 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link) E1000_PCI_LTR_CAP_LPT + 2, &max_nosnoop); max_ltr_enc = max_t(u16, max_snoop, max_nosnoop); - if (lat_enc > max_ltr_enc) + if (decoded_ltr(lat_enc) > decoded_ltr(max_ltr_enc)) lat_enc = max_ltr_enc; } -- 2.25.1