[PATCH] Revert "ath9k_hw: Fix incorrect spur_freq_sd for AR9003"

[PATCH] Revert "ath9k_hw: Fix incorrect spur_freq_sd for AR9003"

[Rajkumar Manoharan]

This reverts commit a844adfd7bee4edc66d337de6c33b348e83552a8.

spur_freq_sd (for self-corr in AGC) is defined with respect to the
center of each 20MHz channel while spur_phase_delta (for self-corr
in Rx and spur data filter) is defined with respect to the center
of current RF channel.

So in short, we need to subtract spur_freq_sd (for self-corr in AGC)
by the offset between the center of primary20 and the center of RF
channel in SW. This offset could be +/10 MHz for dynamic 40.

Cc: Madhan Jaganathan <madhanj@qca.qualcomm.com>
Signed-off-by: Kai Shi <kaishi@qca.qualcomm.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
---
 drivers/net/wireless/ath/ath9k/ar9003_phy.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/ar9003_phy.c b/drivers/net/wireless/ath/ath9k/ar9003_phy.c
index 5358553..11abb97 100644
--- a/drivers/net/wireless/ath/ath9k/ar9003_phy.c
+++ b/drivers/net/wireless/ath/ath9k/ar9003_phy.c
@@ -373,7 +373,7 @@ static void ar9003_hw_spur_ofdm_work(struct ath_hw *ah,
 			else
 				spur_subchannel_sd = 0;
 
-			spur_freq_sd = (freq_offset << 9) / 11;
+			spur_freq_sd = ((freq_offset + 10) << 9) / 11;
 
 		} else {
 			if (REG_READ_FIELD(ah, AR_PHY_GEN_CTRL,
@@ -382,7 +382,7 @@ static void ar9003_hw_spur_ofdm_work(struct ath_hw *ah,
 			else
 				spur_subchannel_sd = 1;
 
-			spur_freq_sd = (freq_offset << 9) / 11;
+			spur_freq_sd = ((freq_offset - 10) << 9) / 11;
 
 		}
 
-- 
1.7.10

Re: [PATCH] Revert "ath9k_hw: Fix incorrect spur_freq_sd for AR9003"

[John W. Linville]

On Sat, Apr 28, 2012 at 11:58:41AM +0530, Rajkumar Manoharan wrote:
> This reverts commit a844adfd7bee4edc66d337de6c33b348e83552a8.
> 
> spur_freq_sd (for self-corr in AGC) is defined with respect to the
> center of each 20MHz channel while spur_phase_delta (for self-corr
> in Rx and spur data filter) is defined with respect to the center
> of current RF channel.
> 
> So in short, we need to subtract spur_freq_sd (for self-corr in AGC)
> by the offset between the center of primary20 and the center of RF
> channel in SW. This offset could be +/10 MHz for dynamic 40.
> 
> Cc: Madhan Jaganathan <madhanj@qca.qualcomm.com>
> Signed-off-by: Kai Shi <kaishi@qca.qualcomm.com>
> Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>

What actual bug is this causing?  Should this be applied to 3.4?

> ---
>  drivers/net/wireless/ath/ath9k/ar9003_phy.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath9k/ar9003_phy.c b/drivers/net/wireless/ath/ath9k/ar9003_phy.c
> index 5358553..11abb97 100644
> --- a/drivers/net/wireless/ath/ath9k/ar9003_phy.c
> +++ b/drivers/net/wireless/ath/ath9k/ar9003_phy.c
> @@ -373,7 +373,7 @@ static void ar9003_hw_spur_ofdm_work(struct ath_hw *ah,
>  			else
>  				spur_subchannel_sd = 0;
>  
> -			spur_freq_sd = (freq_offset << 9) / 11;
> +			spur_freq_sd = ((freq_offset + 10) << 9) / 11;
>  
>  		} else {
>  			if (REG_READ_FIELD(ah, AR_PHY_GEN_CTRL,
> @@ -382,7 +382,7 @@ static void ar9003_hw_spur_ofdm_work(struct ath_hw *ah,
>  			else
>  				spur_subchannel_sd = 1;
>  
> -			spur_freq_sd = (freq_offset << 9) / 11;
> +			spur_freq_sd = ((freq_offset - 10) << 9) / 11;
>  
>  		}
>  
> -- 
> 1.7.10
> 
> 

-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

Re: [PATCH] Revert "ath9k_hw: Fix incorrect spur_freq_sd for AR9003"

[Rajkumar Manoharan]

On Mon, Apr 30, 2012 at 02:22:01PM -0400, John W. Linville wrote:
> On Sat, Apr 28, 2012 at 11:58:41AM +0530, Rajkumar Manoharan wrote:
> > This reverts commit a844adfd7bee4edc66d337de6c33b348e83552a8.
> > 
> > spur_freq_sd (for self-corr in AGC) is defined with respect to the
> > center of each 20MHz channel while spur_phase_delta (for self-corr
> > in Rx and spur data filter) is defined with respect to the center
> > of current RF channel.
> > 
> > So in short, we need to subtract spur_freq_sd (for self-corr in AGC)
> > by the offset between the center of primary20 and the center of RF
> > channel in SW. This offset could be +/10 MHz for dynamic 40.
> > 
> > Cc: Madhan Jaganathan <madhanj@qca.qualcomm.com>
> > Signed-off-by: Kai Shi <kaishi@qca.qualcomm.com>
> > Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
> 
> What actual bug is this causing?  Should this be applied to 3.4?
> 
The original commmit is causing low rate's sensitivity degrade in ht40
mode. Will send v2 patch with updated commit log. And yes it should be
applied to 3.4.

-Rajkumar