On Thu, 2008-01-03 at 14:15 +0800, Shaohua Li wrote: > PCI Express ASPM defines a protocol for PCI Express components in the D0 > state to reduce Link power by placing their Links into a low power state > and instructing the other end of the Link to do likewise. This > capability allows hardware-autonomous, dynamic Link power reduction > beyond what is achievable by software-only controlled power management. > However, The device should be configured by software appropriately. > Enabling ASPM will save power, but will introduce device latency. > > This patch adds ASPM support in Linux. It introduces a global policy for > ASPM, a sysfs file /sys/module/pcie_aspm/parameters/policy can control > it. The interface can be used as a boot option too. Currently we have > below setting: > -default, BIOS default setting > -powersave, highest power saving mode, enable all available ASPM state > and clock power management > -performance, highest performance, disable ASPM and clock power > management > By default, the 'default' policy is used currently. > > In my test, power difference between powersave mode and performance mode > is about 1.3w in a system with 3 PCIE links. > > please review, any comments will be appreciated. > > Signed-off-by: Shaohua Li <[EMAIL PROTECTED]>
Minor nit, but you do a lot of these: + return ((struct link_state *)pdev->link_state)->bios_aspm_state; + return ((struct link_state *)pdev->link_state)->bios_clk_state; + ((struct link_state*)pdev->link_state)->clk_pm_enabled = !!enable; + ((struct link_state*)pdev->link_state)->clk_pm_capable = capable; + ((struct link_state*)pdev->link_state)->clk_pm_enabled = enabled; + ((struct link_state*)pdev->link_state)->bios_clk_state = enabled; + ((struct link_state *)pdev->link_state)->enabled_state = state; + if (((struct link_state *)pdev->link_state)->support_state == 0) + if (((struct link_state *)pdev->link_state)->enabled_state == state) + ((struct link_state *)pdev->link_state)->enabled_state); Which is a little hard on the eye. cheers -- Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person
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