Hi, I have addressed your concerns below: >-----Original Message----- >From: Dominik Brodowski [mailto:linux@xxxxxxxxxxxxxxxxxxxx] >Sent: Friday, December 11, 2009 5:13 PM >To: Chumbalkar, Nagananda >Cc: davej@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; >cpufreq@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; >mjg@xxxxxxxxxx; trenn@xxxxxxx; lenb@xxxxxxxxxx >Subject: Re: [PATCH] cpufreq: Processor Clocking Control >interface driver > >Hey, > >On Fri, Dec 11, 2009 at 10:55:40PM +0000, Naga Chumbalkar wrote: >> +The VERSION number for the driver will be of the format v.xy.ab. >> +eg: 1.00.02 >> + ----- -- >> + | | >> + | -- this will increase with bug fixes/enhancements >to the driver >> + |-- this is the version of the PCC specification the >driver adheres to > >If this is _really_ necessary... Doesn't the driver version >relate to some >Linux kernel version anyway? > If distros backport this driver to different kernel versions, it will be easy to keep track of which driver version is in the distro. >> +2.1 scaling_available_frequencies: >> +---------------------------------- >> +scaling_available_frequencies indicates the minimum and >maximum speed >> +the CPU can take as advertised by the BIOS. No intermediate >frequencies are >> +listed because the BIOS will try to achieve any >intermediate frequency >> +requested by the governor. An intermediate frequency does >not have to be >> +strictly associated with a P-state. > >Why do you export scaling_available_frequencies anyway? It's >made available >by the _optional_ freq-table helper module, which is wrong to >use in this >case anyway. > You are correct. I don't need the dependency on CPU_FREQ_TABLE. I ripped it out and made suitable changes: diff -bur orig/pcc-cpufreq.c fix/pcc-cpufreq.c --- orig/pcc-cpufreq.c 2009-11-30 20:05:23.000000000 -0600 +++ fix/pcc-cpufreq.c 2009-11-30 21:14:31.000000000 -0600 @@ -111,15 +111,11 @@ static struct pcc_cpu *pcc_cpu_info; -static struct cpufreq_frequency_table pcc_freq_table[] = { - {0x1, 0}, - {0x2, 0}, - {0, CPUFREQ_TABLE_END}, -}; - static int pcc_cpufreq_verify(struct cpufreq_policy *policy) { - return cpufreq_frequency_table_verify(policy, pcc_freq_table); + cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, + policy->cpuinfo.max_freq); + return 0; } static inline void pcc_cmd(void) @@ -534,10 +530,6 @@ goto pcch_free; } - pcc_freq_table[0].frequency = - ioread32(&pcch_hdr->minimum_frequency) * 1000; - pcc_freq_table[1].frequency = ioread32(&pcch_hdr->nominal) * 1000; - printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency" " limits: %d MHz, %d MHz\n", PCC_VERSION, ioread32(&pcch_hdr->minimum_frequency), @@ -576,12 +568,6 @@ dprintk("init: policy->max is %d, policy->min is %d\n", policy->max, policy->min); - result = cpufreq_frequency_table_cpuinfo(policy, pcc_freq_table); - if (result) - goto free; - - cpufreq_frequency_table_get_attr(pcc_freq_table, policy->cpu); - return 0; free: pcc_clear_mapping(); @@ -592,15 +578,9 @@ static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy) { - cpufreq_frequency_table_put_attr(policy->cpu); return 0; } -static struct freq_attr *pcc_cpufreq_attr[] = { - &cpufreq_freq_attr_scaling_available_freqs, - NULL, -}; - static struct cpufreq_driver pcc_cpufreq_driver = { .flags = CPUFREQ_CONST_LOOPS, .get = pcc_get_freq, @@ -610,7 +590,6 @@ .exit = pcc_cpufreq_cpu_exit, .name = "pcc-cpufreq", .owner = THIS_MODULE, - .attr = pcc_cpufreq_attr, }; static int __init pcc_cpufreq_init(void) diff -bur orig/pcc-cpufreq.txt fix/pcc-cpufreq.txt --- orig/pcc-cpufreq.txt 2009-11-30 20:05:55.000000000 -0600 +++ fix/pcc-cpufreq.txt 2009-11-30 21:15:10.000000000 -0600 @@ -152,11 +152,10 @@ 2.1 scaling_available_frequencies: ---------------------------------- -scaling_available_frequencies indicates the minimum and maximum speed -the CPU can take as advertised by the BIOS. No intermediate frequencies are -listed because the BIOS will try to achieve any intermediate frequency -requested by the governor. An intermediate frequency does not have to be -strictly associated with a P-state. +scaling_available_frequencies is not created in /sys. No intermediate +frequencies need to be listed because the BIOS will try to achieve any +frequency, within limits, requested by the governor. A frequency does not have +to be strictly associated with a P-state. 2.2 cpuinfo_transition_latency: ------------------------------- @@ -203,7 +202,7 @@ 3. Caveats: ----------- -Currently, the "cpufreq_stats" module in its present form cannot be loaded and -expected to work with the PCC driver. A patch to cpufreq_stats will be -submitted to fix this. +The "cpufreq_stats" module in its present form cannot be loaded and +expected to work with the PCC driver. Since the "cpufreq_stats" module +provides information wrt each P-state, it is not applicable to the PCC driver. >> +2.2 cpuinfo_transition_latency: >> +------------------------------- >> +The cpuinfo_transition_latency field is 0. The PCC >specification does >> +not include a field to expose this value currently. > >Uh, bad specification... So does it work properly with ondemand and/or >conservative (which read out this field, and if latency=0 use a minimum >value)? > Yes, it works fine. Both "ondemand" and "conservative" sanitize the latency value, and set it to a default value which is good. >> +config X86_PCC_CPUFREQ >> + tristate "Processor Clocking Control interface driver" >> + select CPU_FREQ_TABLE >Uh, see above. > diff -bur orig/Kconfig fix/Kconfig --- orig/Kconfig 2009-11-30 20:05:32.000000000 -0600 +++ fix/Kconfig 2009-11-30 21:14:47.000000000 -0600 @@ -12,7 +12,6 @@ config X86_PCC_CPUFREQ tristate "Processor Clocking Control interface driver" - select CPU_FREQ_TABLE depends on ACPI && ACPI_PROCESSOR help This driver adds support for the PCC interface. >> +static int pcc_cpufreq_verify(struct cpufreq_policy *policy) >> +{ >> + return cpufreq_frequency_table_verify(policy, pcc_freq_table); >> +} > >Well, AFAICS, this limits the whole interface to two values: >min or max. So >let's allow for any intermediate value: > >static int pcc_cpufreq_verify(struct cpufreq_policy *policy) >{ > cpufreq_verify_within_limits(policy, >policy->cpuinfo.min_freq, policy->cpuinfo.max_freq); >} > Took this suggestion, (see the first "diff" changeset above), especially since I cannot use the freq-table helper function anymore. >but well... later on, you check this > >> + if (target_freq <= >(ioread32(&pcch_hdr->minimum_frequency) * 1000)) { >> + target_freq = >ioread32(&pcch_hdr->minimum_frequency) * 1000; >> + dprintk("target: target_freq for cpu %d was >below limit, " >> + "converted it to %d\n", cpu, target_freq); >> + } > >why not do this in the _verify() step? Does pcch_hdr->minimum_frequency >even change "on the fly"? pcch_hdr->minimum_frequency does not change "on the fly". Also, there is no need for those IO accesses: diff -bur orig/pcc-cpufreq.c fix/pcc-cpufreq.c --- orig/pcc-cpufreq.c 2009-12-15 10:52:01.000000000 -0600 +++ fix/pcc-cpufreq.c 2009-12-15 10:52:06.000000000 -0600 @@ -212,12 +212,18 @@ pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu); - if (target_freq <= (ioread32(&pcch_hdr->minimum_frequency) * 1000)) { - target_freq = ioread32(&pcch_hdr->minimum_frequency) * 1000; + if (target_freq < policy->min) { + target_freq = policy->min; dprintk("target: target_freq for cpu %d was below limit, " "converted it to %d\n", cpu, target_freq); } + if (target_freq > policy->max) { + target_freq = policy->max; + dprintk("target: target_freq for cpu %d was above limit, " + "converted it to %d\n", cpu, target_freq); + } + dprintk("target: CPU %d should go to target freq: %d " "(virtual) input_offset is 0x%x\n", cpu, target_freq, > >So, I'd propose to NACK this patch at the moment. > >Best, > Dominik > If you are okay with the changes, I will send v2 of the patch. Thanks, - naga - -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
