Commit a1d1d8fb authored by Dhananjay Ugwekar's avatar Dhananjay Ugwekar Committed by Mario Limonciello
Browse files

cpufreq/amd-pstate: Fix the clamping of perf values 



The clamping in freq_to_perf() is broken right now, as we first typecast
(read wraparound) the overflowing value into a u8 and then clamp it down.
So, use a u32 to store the >255 value in certain edge cases and then clamp
it down into a u8.

Also, use a "explicit typecast + clamp" instead of just a "clamp_t" as the
latter typecasts first and then clamps between the limits, which defeats
our purpose.

Fixes: 620136ce ("cpufreq/amd-pstate: Modularize perf<->freq conversion")
Signed-off-by: default avatarDhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Reviewed-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20250222033221.554976-1-dhananjay.ugwekar@amd.com


Signed-off-by: default avatarMario Limonciello <mario.limonciello@amd.com>
parent 3e93edc5

drivers/cpufreq/amd-pstate.c

+2 −2
Original line number Diff line number Diff line
@@ -144,10 +144,10 @@ static struct quirk_entry quirk_amd_7k62 = { 


static inline u8 freq_to_perf(struct amd_cpudata *cpudata, unsigned int freq_val)

{

	u8 perf_val = DIV_ROUND_UP_ULL((u64)freq_val * cpudata->nominal_perf,

	u32 perf_val = DIV_ROUND_UP_ULL((u64)freq_val * cpudata->nominal_perf,

					cpudata->nominal_freq);



	return clamp_t(u8, perf_val, cpudata->lowest_perf, cpudata->highest_perf);

	return (u8)clamp(perf_val, cpudata->lowest_perf, cpudata->highest_perf);

}



static inline u32 perf_to_freq(struct amd_cpudata *cpudata, u8 perf_val)