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Date: Tue, 19 Nov 2013 08:16:33 -0600 From: Nishanth Menon <nm@...com> To: Viresh Kumar <viresh.kumar@...aro.org>, Shawn Guo <shawn.guo@...aro.org> CC: "Rafael J. Wysocki" <rjw@...ysocki.net>, "cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>, "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Carlos Hernandez <ceh@...com> Subject: Re: [PATCH] cpufreq: cpufreq-cpu0: Use a sane boot frequency when booting with a mismatched bootloader configuration On 11/18/2013 09:46 PM, Viresh Kumar wrote: > On 19 November 2013 07:51, Shawn Guo <shawn.guo@...aro.org> wrote: >> No, I did not say that. IMO, when cpufreq-cpu0 sees a mismatch, it has >> no way to know or assume which one is correct and which is incorrect. >> The best thing it can do is to fail out without changing anything about >> running frequency and voltage. > > Not specifically on this patch, but this is what I feel about this issue: > > - As we are discussing on the other thread, there is scope of adding > "unknown" field in tables so that people would know that they were > running out of table freq at some point.. Consider something like userspace governor selection -> the device at boot will probably remain in an unknown/"invalid" configuration till the very first transition attempt. I am less worried about the stats than not following what the hardware description is (as stated by device tree/other forms). I staunchly disagree that at a point of mismatch detection, we just refuse to load up cpufreq governor -even though we know from device tree/other alternative entries what the hardware behavior is supposed to be. To refuse to loadup to a known configuration is considering the "valid configuration" data provided to the driver is wrong - an equivalent(considering the i2c example) is that if i2c driver sees bus configured for 3.4MHz and was asked to use 100KHz, it just refuses to load up! > - This is a common problem for all drivers/platforms and not only > cpufreq-cpu0, so the solution has to be generic and not driver > specific.. So, atleast I don't want to get this patch in at any cost, > unless there is a generic solution present.. > - There are non-dt drivers as well, and so freq table is present > with the kernel and we can't support all frequencies that bootloader > may end up with.. The above two are fair comments -> but that implies that policy->cur population should no longer be the responsibility of cpufreq drivers and be the responsibility of cpufreq core. are we stating we want to move that to cpufreq core? -- Regards, Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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