From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-2?Q?Rafa=B3_Bilski?= Subject: Re: [PATCH] Longhaul - Add ignore_latency option Date: Thu, 24 Aug 2006 19:18:14 +0200 Message-ID: <44EDDF56.2060807@interia.pl> References: <44DED1C4.7060108@interia.pl> <200608232322.19005.len.brown@intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <200608232322.19005.len.brown@intel.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@lists.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=m.gmane.org+glkc-cpufreq=m.gmane.org@lists.linux.org.uk Content-Type: text/plain; charset="iso-8859-9" To: Len Brown Cc: cpufreq@lists.linux.org.uk >> Some laptops with VIA C3 processor, CLE266 chipset and >> AMI BIOS have incorrect latency values in FADT table. These >> laptops seems to be C3 capable, but latency values are to >> big: 101 for C2 and 1017 for C3. This option will allow >> user to skip C3 latency test but not C3 address test. AMI >> BIOS is setting C3 address to correct value in DSDT table. >=20 > This looks very fishy. So why P_BLK address is valid and have proper lenght? >=20 > C2 latency above 100usec and C3 latency above 1000 usec > are the official way for the BIOS to tell the OS to NOT USE > those C-states. Under no conditions should Linux second > guess those explicit instructions -- the BIOS may have put > those values there because you get silent data corruption > on that particular stepping of the processor or chipset > if they are enabled. >=20 It is disabled by default. It is only needed for some laptops. As far I know there is no data corruption. Chipset and processor=20 are exacly the same as on Epia M10000 so I don't expect any. Why force user to recompilation of distro kernel? > But the real question is why the longhaul driver is checking > for C2 and C3 support in the first place -- as they are not > directly related to the availability of P-states. >=20 > -Len >=20 Because Longhaul isn't using P-states. Rafa=B3 ---------------------------------------------------------------------- Zostan Chlopakiem Lata! >>> http://link.interia.pl/f1998