4.15-stable review patch. If anyone has any objections, please let me know.
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From: "Gautham R. Shenoy" ego@linux.vnet.ibm.com
[ Upstream commit ee1f4a7dafa997816ff3de96155c6f3edc21c1e6 ]
On POWERNV platform, the fields for pstates in the Power Management Status Register (PMSR) and the Power Management Control Register (PMCR) are 8-bits wide. On POWER8 the pstates are negatively numbered while on POWER9 they are positively numbered.
The device-tree exports pstates as 32-bit entries. The device-tree implementation sign-extends the 8-bit pstate values to obtain the corresponding 32-bit entry.
Eg: On POWER8, a pstate value 0x82 [-126] is represented in the device-tree as 0xfffffff82 while on POWER9, the same value 0x82 [130] is represented in the device-tree as 0x00000082.
The powernv-cpufreq driver implementation represents pstates using the integer type. In multiple places in the driver, the code interprets the pstates extracted from the PMSR as a signed byte and assigns it to a integer variable to get the sign-extention.
On POWER9 platforms which have greater than 128 pstates, this results in the driver performing incorrect sign-extention, and thereby treating a legitimate pstate (say 130) as an invalid pstates (since it is interpreted as -126).
This patch fixes the issue by implementing a helper function to extract Pstates from PMSR register, and correctly sign-extend it to be consistent with the values provided by the device-tree.
Signed-off-by: Gautham R. Shenoy ego@linux.vnet.ibm.com Acked-by: Balbir Singh bsingharora@gmail.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cpufreq/powernv-cpufreq.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-)
--- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -41,11 +41,9 @@ #define POWERNV_MAX_PSTATES 256 #define PMSR_PSAFE_ENABLE (1UL << 30) #define PMSR_SPR_EM_DISABLE (1UL << 31) -#define PMSR_MAX(x) ((x >> 32) & 0xFF) +#define MAX_PSTATE_SHIFT 32 #define LPSTATE_SHIFT 48 #define GPSTATE_SHIFT 56 -#define GET_LPSTATE(x) (((x) >> LPSTATE_SHIFT) & 0xFF) -#define GET_GPSTATE(x) (((x) >> GPSTATE_SHIFT) & 0xFF)
#define MAX_RAMP_DOWN_TIME 5120 /* @@ -94,6 +92,7 @@ struct global_pstate_info { };
static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; +u32 pstate_sign_prefix; static bool rebooting, throttled, occ_reset;
static const char * const throttle_reason[] = { @@ -148,6 +147,20 @@ static struct powernv_pstate_info { bool wof_enabled; } powernv_pstate_info;
+static inline int extract_pstate(u64 pmsr_val, unsigned int shift) +{ + int ret = ((pmsr_val >> shift) & 0xFF); + + if (!ret) + return ret; + + return (pstate_sign_prefix | ret); +} + +#define extract_local_pstate(x) extract_pstate(x, LPSTATE_SHIFT) +#define extract_global_pstate(x) extract_pstate(x, GPSTATE_SHIFT) +#define extract_max_pstate(x) extract_pstate(x, MAX_PSTATE_SHIFT) + /* Use following macros for conversions between pstate_id and index */ static inline int idx_to_pstate(unsigned int i) { @@ -278,6 +291,9 @@ next:
powernv_pstate_info.nr_pstates = nr_pstates; pr_debug("NR PStates %d\n", nr_pstates); + + pstate_sign_prefix = pstate_min & ~0xFF; + for (i = 0; i < nr_pstates; i++) { u32 id = be32_to_cpu(pstate_ids[i]); u32 freq = be32_to_cpu(pstate_freqs[i]); @@ -438,17 +454,10 @@ struct powernv_smp_call_data { static void powernv_read_cpu_freq(void *arg) { unsigned long pmspr_val; - s8 local_pstate_id; struct powernv_smp_call_data *freq_data = arg;
pmspr_val = get_pmspr(SPRN_PMSR); - - /* - * The local pstate id corresponds bits 48..55 in the PMSR. - * Note: Watch out for the sign! - */ - local_pstate_id = (pmspr_val >> 48) & 0xFF; - freq_data->pstate_id = local_pstate_id; + freq_data->pstate_id = extract_local_pstate(pmspr_val); freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n", @@ -522,7 +531,7 @@ static void powernv_cpufreq_throttle_che chip = this_cpu_read(chip_info);
/* Check for Pmax Capping */ - pmsr_pmax = (s8)PMSR_MAX(pmsr); + pmsr_pmax = extract_max_pstate(pmsr); pmsr_pmax_idx = pstate_to_idx(pmsr_pmax); if (pmsr_pmax_idx != powernv_pstate_info.max) { if (chip->throttled) @@ -645,8 +654,8 @@ void gpstate_timer_handler(struct timer_ * value. Hence, read from PMCR to get correct data. */ val = get_pmspr(SPRN_PMCR); - freq_data.gpstate_id = (s8)GET_GPSTATE(val); - freq_data.pstate_id = (s8)GET_LPSTATE(val); + freq_data.gpstate_id = extract_global_pstate(val); + freq_data.pstate_id = extract_local_pstate(val); if (freq_data.gpstate_id == freq_data.pstate_id) { reset_gpstates(policy); spin_unlock(&gpstates->gpstate_lock);