We expose the actual memory controller clock rate in Linux, not the effective memory clock of the DRAMs. To translate it, it follows the following formula: Clock conversion (Mhz): HBM: effective_memory_clock = memory_controller_clock * 1 G5: effective_memory_clock = memory_controller_clock * 1 G6: effective_memory_clock = memory_controller_clock * 2 DRAM data rate (MT/s): HBM: effective_memory_clock * 2 = data_rate G5: effective_memory_clock * 4 = data_rate G6: effective_memory_clock * 8 = data_rate Bandwidth (MB/s): data_rate * vram_bit_width / 8 = memory_bandwidth Some examples: G5 on RX460: memory_controller_clock = 1750 Mhz effective_memory_clock = 1750 Mhz * 1 = 1750 Mhz data rate = 1750 * 4 = 7000 MT/s memory_bandwidth = 7000 * 128 bits / 8 = 112000 MB/s G6 on RX5600: memory_controller_clock = 900 Mhz effective_memory_clock = 900 Mhz * 2 = 1800 Mhz data rate = 1800 * 8 = 14400 MT/s memory_bandwidth = 14400 * 192 bits / 8 = 345600 MB/s Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> --- drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 46 ++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c index 20f39aa04fb9..dd05751f6b35 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c @@ -694,6 +694,52 @@ static ssize_t amdgpu_set_pp_table(struct device *dev, * in each power level within a power state. The pp_od_clk_voltage is used for * this. * + * Note that the actual memory controller clock rate are exposed, not + * the effective memory clock of the DRAMs. To translate it, use the + * following formula: + * + * Clock conversion (Mhz): + * + * HBM: effective_memory_clock = memory_controller_clock * 1 + * + * G5: effective_memory_clock = memory_controller_clock * 1 + * + * G6: effective_memory_clock = memory_controller_clock * 2 + * + * DRAM data rate (MT/s): + * + * HBM: effective_memory_clock * 2 = data_rate + * + * G5: effective_memory_clock * 4 = data_rate + * + * G6: effective_memory_clock * 8 = data_rate + * + * Bandwidth (MB/s): + * + * data_rate * vram_bit_width / 8 = memory_bandwidth + * + * Some examples: + * + * G5 on RX460: + * + * memory_controller_clock = 1750 Mhz + * + * effective_memory_clock = 1750 Mhz * 1 = 1750 Mhz + * + * data rate = 1750 * 4 = 7000 MT/s + * + * memory_bandwidth = 7000 * 128 bits / 8 = 112000 MB/s + * + * G6 on RX5700: + * + * memory_controller_clock = 875 Mhz + * + * effective_memory_clock = 875 Mhz * 2 = 1750 Mhz + * + * data rate = 1750 * 8 = 14000 MT/s + * + * memory_bandwidth = 14000 * 256 bits / 8 = 448000 MB/s + * * < For Vega10 and previous ASICs > * * Reading the file will display: -- 2.25.4 _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
