Hello !
I have found bug in I/Q calibration procedure. Because of this bug calibration
goes wrong, and card receive frames with CRC errors.
In phy.c/ath5k_hw_rf511x_calibrate()
i_coff = ((-iq_corr) / i_coffd) & 0x3f;
but, i_coff is signed 32bit value, but when masking it with 0x3f it becomes
signed positive value 0..63,
but later, at boundary check it compared with (s32)-32 or (s32)31, and all
correct negative values of i_coff always be
greater than 31, and in card will be written not correct value (31 instead of
-5, for example).
Proposed patch fix this bug, and some small differences between ath5k and Sam's
HAL.
--- phy.c.old 2009-04-01 13:57:01.000000000 +0400
+++ phy.c 2009-04-01 14:04:17.000000000 +0400
@@ -1291,16 +1291,17 @@
iq_corr = ath5k_hw_reg_read(ah, AR5K_PHY_IQRES_CAL_CORR);
i_pwr = ath5k_hw_reg_read(ah, AR5K_PHY_IQRES_CAL_PWR_I);
q_pwr = ath5k_hw_reg_read(ah, AR5K_PHY_IQRES_CAL_PWR_Q);
+ if (i_pwr && q_pwr) break;
}
i_coffd = ((i_pwr >> 1) + (q_pwr >> 1)) >> 7;
q_coffd = q_pwr >> 7;
/* No correction */
- if (i_coffd == 0 || q_coffd == 0)
+ if (i_coffd == 0 || q_coffd < 2)
goto done;
- i_coff = ((-iq_corr) / i_coffd) & 0x3f;
+ i_coff = ((-iq_corr) / i_coffd);
/* Boundary check */
if (i_coff > 31)
@@ -1308,7 +1309,7 @@
if (i_coff < -32)
i_coff = -32;
- q_coff = (((s32)i_pwr / q_coffd) - 128) & 0x1f;
+ q_coff = (((s32)i_pwr / q_coffd) - 128);
/* Boundary check */
if (q_coff > 15)
@@ -1318,7 +1319,7 @@
/* Commit new I/Q value */
AR5K_REG_ENABLE_BITS(ah, AR5K_PHY_IQ, AR5K_PHY_IQ_CORR_ENABLE |
- ((u32)q_coff) | ((u32)i_coff << AR5K_PHY_IQ_CORR_Q_I_COFF_S));
+ (((u32)q_coff) & 0x1f) | (((u32)i_coff & 0x3f) <<
AR5K_PHY_IQ_CORR_Q_I_COFF_S));
/* Re-enable calibration -if we don't we'll commit
* the same values again and again */
After applying this patch 48M and 54M data rases work more stable without lots
of CRC errors.
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