From ab1b1c4e8223f9ee66aa93aaf64c36e77cadffac Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Mon, 2 Dec 2013 11:04:13 +0530 Subject: [PATCH] cpufreq: send new set of notification for transition failures In the current code, if we fail during a frequency transition, we simply send the POSTCHANGE notification with the old frequency. This isn't enough. One of the core users of these notifications is the code responsible for keeping loops_per_jiffy aligned with frequency changes. And mostly it is written as: if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { update-loops-per-jiffy... } So, suppose we are changing to a higher frequency and failed during transition, then following will happen: - CPUFREQ_PRECHANGE notification with freq-new > freq-old - CPUFREQ_POSTCHANGE notification with freq-new == freq-old The first one will update loops_per_jiffy and second one will do nothing. Even if we send the 2nd notification by exchanging values of freq-new and old, some users of these notifications might get unstable. This can be fixed by simply calling cpufreq_notify_post_transition() with error code and this routine will take care of sending notifications in the correct order. Signed-off-by: Viresh Kumar [rjw: Folded 3 patches into one, rebased unicore2 changes] Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 13 ++----------- drivers/cpufreq/pcc-cpufreq.c | 18 +++++++----------- drivers/cpufreq/powernow-k8.c | 7 +------ drivers/cpufreq/unicore2-cpufreq.c | 16 +++++++--------- 4 files changed, 17 insertions(+), 37 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index a123a731ec4e..d533c205eea4 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1739,17 +1739,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy, pr_err("%s: Failed to change cpu frequency: %d\n", __func__, retval); - if (notify) { - /* - * Notify with old freq in case we failed to change - * frequency - */ - if (retval) - freqs.new = freqs.old; - - cpufreq_notify_transition(policy, &freqs, - CPUFREQ_POSTCHANGE); - } + if (notify) + cpufreq_notify_post_transition(policy, &freqs, retval); } out: diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c index e2b4f40ff69a..1c0f1067af73 100644 --- a/drivers/cpufreq/pcc-cpufreq.c +++ b/drivers/cpufreq/pcc-cpufreq.c @@ -213,6 +213,7 @@ static int pcc_cpufreq_target(struct cpufreq_policy *policy, cpu, target_freq, (pcch_virt_addr + pcc_cpu_data->input_offset)); + freqs.old = policy->cur; freqs.new = target_freq; cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); @@ -228,25 +229,20 @@ static int pcc_cpufreq_target(struct cpufreq_policy *policy, memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ); status = ioread16(&pcch_hdr->status); + iowrite16(0, &pcch_hdr->status); + + cpufreq_notify_post_transition(policy, &freqs, status != CMD_COMPLETE); + spin_unlock(&pcc_lock); + if (status != CMD_COMPLETE) { pr_debug("target: FAILED for cpu %d, with status: 0x%x\n", cpu, status); - goto cmd_incomplete; + return -EINVAL; } - iowrite16(0, &pcch_hdr->status); - cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); pr_debug("target: was SUCCESSFUL for cpu %d\n", cpu); - spin_unlock(&pcc_lock); return 0; - -cmd_incomplete: - freqs.new = freqs.old; - cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); - iowrite16(0, &pcch_hdr->status); - spin_unlock(&pcc_lock); - return -EINVAL; } static int pcc_get_offset(int cpu) diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c index 0023c7d40a51..e10b646634d7 100644 --- a/drivers/cpufreq/powernow-k8.c +++ b/drivers/cpufreq/powernow-k8.c @@ -964,14 +964,9 @@ static int transition_frequency_fidvid(struct powernow_k8_data *data, cpufreq_cpu_put(policy); cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); - res = transition_fid_vid(data, fid, vid); - if (res) - freqs.new = freqs.old; - else - freqs.new = find_khz_freq_from_fid(data->currfid); + cpufreq_notify_post_transition(policy, &freqs, res); - cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); return res; } diff --git a/drivers/cpufreq/unicore2-cpufreq.c b/drivers/cpufreq/unicore2-cpufreq.c index 653ae2955b55..86f6cfec2e09 100644 --- a/drivers/cpufreq/unicore2-cpufreq.c +++ b/drivers/cpufreq/unicore2-cpufreq.c @@ -46,20 +46,18 @@ static int ucv2_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { - unsigned int cur = ucv2_getspeed(0); struct cpufreq_freqs freqs; struct clk *mclk = clk_get(NULL, "MAIN_CLK"); + int ret; + + freqs.old = policy->cur; + freqs.new = target_freq; cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); + ret = clk_set_rate(mclk, target_freq * 1000); + cpufreq_notify_post_transition(policy, &freqs, ret); - if (!clk_set_rate(mclk, target_freq * 1000)) { - freqs.old = cur; - freqs.new = target_freq; - } - - cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); - - return 0; + return ret; } static int __init ucv2_cpu_init(struct cpufreq_policy *policy)