[{"id":1770629,"web_url":"http://patchwork.ozlabs.org/comment/1770629/","msgid":"<20170919032341.GM378890@devbig577.frc2.facebook.com>","list_archive_url":null,"date":"2017-09-19T03:23:42","subject":"Re: [PATCH] libata: Add new med_power_with_dipm\n\tlink_power_management_policy setting","submitter":{"id":352,"url":"http://patchwork.ozlabs.org/api/people/352/","name":"Tejun Heo","email":"tj@kernel.org"},"content":"On Thu, Sep 14, 2017 at 12:35:36PM +0200, Hans de Goede wrote:\n> As described by Matthew Garret quite a while back:\n> https://mjg59.dreamwidth.org/34868.html\n> \n> Intel CPUs starting with the Haswell generation need SATA links to power\n> down for the \"package\" part of the CPU to reach low power-states like\n> PC7 / P8 which bring a significant power-saving with them.\n> \n> The default max_performance lpm policy does not allow for these high\n> PC states, both the medium_power and min_power policies do allow this.\n> \n> The min_power policy saves significantly more power, but there are some\n> reports of some disks / SSDs not liking min_power leading to system\n> crashes and in some cases even data corruption has been reported.\n> \n> Matthew has found a document documenting the default settings of\n> Intel's IRST Windows driver with which most laptops ship:\n> https://www-ssl.intel.com/content/dam/doc/reference-guide/sata-devices-implementation-recommendations.pdf\n> \n> Matthew wrote a patch changing med_power to match those defaults, but\n> that never got anywhere as some people where reporting issues with the\n> patch-set that patch was a part of.\n> \n> This commit is another attempt to make the default IRST driver settings\n> available under Linux, but instead of changing medium_power and\n> potentially introducing regressions, this commit adds a new\n> med_power_with_dipm setting which is identical to the existing\n> medium_power accept that it enables dipm on top, which makes it match\n> the Windows IRST driver settings, which should hopefully be safe to\n> use on most devices.\n> \n> The med_power_with_dipm setting is close to min_power, except that:\n> a) It does not use host-initiated slumber mode (ASP not set),\n> but it does allow device-initiated slumber\n> b) It does not enable DevSlp mode\n> \n> On my T440s test laptop I get the following power savings when idle:\n> medium_power\t\t0.9W\n> med_power_with_dipm\t1.2W\n> min_power\t\t1.2W\n> \n> Suggested-by: Matthew Garrett \n> Cc: Matthew Garrett \n> Signed-off-by: Hans de Goede \n\nApplied to libata/for-4.15.\n\nThanks.","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; 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