From 9c8426fc79eef00464d33e774085395cac41d091 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Tue, 28 May 2013 18:04:44 +0200 Subject: [PATCH] ath9k_hw: fix PA predistortion miscalibration If any bins from the training data are skipped (i != max_index), the calculated compensation curve gets distorted, and the signal will be wildly overamplified. This may be the cause of the reported hardware damage that was caused by PA predistortion (because of which PAPRD was disabled by default). When calculating the x_est, Y, theta values, the use of max_index and i was reversed. i points to the bin index whereas max_index refers to the index of the calculated arrays. Note that PA predistortion is still disabled, it will be re-enabled after it has been properly validated. Signed-off-by: Felix Fietkau Signed-off-by: John W. Linville --- drivers/net/wireless/ath/ath9k/ar9003_paprd.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireless/ath/ath9k/ar9003_paprd.c b/drivers/net/wireless/ath/ath9k/ar9003_paprd.c index 09c1f9da67a0..6343cc91953e 100644 --- a/drivers/net/wireless/ath/ath9k/ar9003_paprd.c +++ b/drivers/net/wireless/ath/ath9k/ar9003_paprd.c @@ -454,6 +454,8 @@ static bool create_pa_curve(u32 *data_L, u32 *data_U, u32 *pa_table, u16 *gain) if (accum_cnt <= thresh_accum_cnt) continue; + max_index++; + /* sum(tx amplitude) */ accum_tx = ((data_L[i] >> 16) & 0xffff) | ((data_U[i] & 0x7ff) << 16); @@ -468,20 +470,21 @@ static bool create_pa_curve(u32 *data_L, u32 *data_U, u32 *pa_table, u16 *gain) accum_tx <<= scale_factor; accum_rx <<= scale_factor; - x_est[i + 1] = (((accum_tx + accum_cnt) / accum_cnt) + 32) >> - scale_factor; + x_est[max_index] = + (((accum_tx + accum_cnt) / accum_cnt) + 32) >> + scale_factor; - Y[i + 1] = ((((accum_rx + accum_cnt) / accum_cnt) + 32) >> + Y[max_index] = + ((((accum_rx + accum_cnt) / accum_cnt) + 32) >> scale_factor) + - (1 << scale_factor) * max_index + 16; + (1 << scale_factor) * i + 16; if (accum_ang >= (1 << 26)) accum_ang -= 1 << 27; - theta[i + 1] = ((accum_ang * (1 << scale_factor)) + accum_cnt) / - accum_cnt; - - max_index++; + theta[max_index] = + ((accum_ang * (1 << scale_factor)) + accum_cnt) / + accum_cnt; } /*