On Wed, Jul 22, 2009 at 09:16:27AM +0800, Kenji Kaneshige wrote: > The L0s state can be managed separately for each direction (upstream > direction and downstream direction) of the link. But in the current > implementation, those are mixed up. With this patch, L0s for each > direction are managed separately. > > To maintain three states (upstream direction L0s, downstream L0s and > L1), 'aspm_support', 'aspm_enabled', 'aspm_capable', 'aspm_disable' > and 'aspm_default' fields in struct pcie_link_state are changed to > 3-bit from 2-bit. The 'latency' field is separated to two 'latency_up' > and 'latency_dw' fields to maintain exit latencies for each direction > of the link. For L0, 'latency_up.l0' and 'latency_dw.l0' are used to > configure upstream direction L0s and downstream direction L0s > respectively. For L1, larger value of 'latency_up.l1' and > 'latency_dw.l1' is considered as L1 exit latency. snip > + > + /* Setup upstream direction L0s state */ > + if (dwreg.support & PCIE_LINK_STATE_L0S) > + link->aspm_support |= ASPM_STATE_L0S_UP; > + if (dwreg.enabled & PCIE_LINK_STATE_L0S) > + link->aspm_enabled |= ASPM_STATE_L0S_UP; > + link->latency_up.l0s = calc_l0s_latency(upreg.latency_encoding_l0s); > + > + /* Setup downstream direction L0s state */ > + if (upreg.support & PCIE_LINK_STATE_L0S) > + link->aspm_support |= ASPM_STATE_L0S_DW; > + if (upreg.enabled & PCIE_LINK_STATE_L0S) > + link->aspm_enabled |= ASPM_STATE_L0S_DW; > + link->latency_dw.l0s = calc_l0s_latency(dwreg.latency_encoding_l0s); > + Somebody (from HP, IIRC) said a lot of systems don't implement one direction L0S right if the other direction doesn't support it. And there is a recent pcisig draft clarifies that software must not enable L0s in either direction on a given link unless components on both sides of the link each support L0s. Let's comfrom to it. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
