drivers/net/wireless/ath/ath9k/ani.c

Source file repositories/reference/linux-study-clean/drivers/net/wireless/ath/ath9k/ani.c

File Facts

System
Linux kernel
Corpus path
drivers/net/wireless/ath/ath9k/ani.c
Extension
.c
Size
15768 bytes
Lines
514
Domain
Driver Families
Bucket
drivers/net
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct ani_ofdm_level_entry {
	int spur_immunity_level;
	int fir_step_level;
	int ofdm_weak_signal_on;
};

/* values here are relative to the INI */

/*
 * Legend:
 *
 * SI: Spur immunity
 * FS: FIR Step
 * WS: OFDM / CCK Weak Signal detection
 * MRC-CCK: Maximal Ratio Combining for CCK
 */

static const struct ani_ofdm_level_entry ofdm_level_table[] = {
	/* SI  FS  WS */
	{  0,  0,  1  }, /* lvl 0 */
	{  1,  1,  1  }, /* lvl 1 */
	{  2,  2,  1  }, /* lvl 2 */
	{  3,  2,  1  }, /* lvl 3  (default) */
	{  4,  3,  1  }, /* lvl 4 */
	{  5,  4,  1  }, /* lvl 5 */
	{  6,  5,  1  }, /* lvl 6 */
	{  7,  6,  1  }, /* lvl 7 */
	{  7,  7,  1  }, /* lvl 8 */
	{  7,  8,  0  }  /* lvl 9 */
};
#define ATH9K_ANI_OFDM_NUM_LEVEL \
	ARRAY_SIZE(ofdm_level_table)
#define ATH9K_ANI_OFDM_MAX_LEVEL \
	(ATH9K_ANI_OFDM_NUM_LEVEL-1)
#define ATH9K_ANI_OFDM_DEF_LEVEL \
	3 /* default level - matches the INI settings */

/*
 * MRC (Maximal Ratio Combining) has always been used with multi-antenna ofdm.
 * With OFDM for single stream you just add up all antenna inputs, you're
 * only interested in what you get after FFT. Signal alignment is also not
 * required for OFDM because any phase difference adds up in the frequency
 * domain.
 *
 * MRC requires extra work for use with CCK. You need to align the antenna
 * signals from the different antenna before you can add the signals together.
 * You need alignment of signals as CCK is in time domain, so addition can cancel
 * your signal completely if phase is 180 degrees (think of adding sine waves).
 * You also need to remove noise before the addition and this is where ANI
 * MRC CCK comes into play. One of the antenna inputs may be stronger but
 * lower SNR, so just adding after alignment can be dangerous.
 *
 * Regardless of alignment in time, the antenna signals add constructively after
 * FFT and improve your reception. For more information:
 *
 * https://en.wikipedia.org/wiki/Maximal-ratio_combining
 */

struct ani_cck_level_entry {
	int fir_step_level;
	int mrc_cck_on;
};

static const struct ani_cck_level_entry cck_level_table[] = {
	/* FS  MRC-CCK  */
	{  0,  1  }, /* lvl 0 */
	{  1,  1  }, /* lvl 1 */
	{  2,  1  }, /* lvl 2  (default) */
	{  3,  1  }, /* lvl 3 */
	{  4,  0  }, /* lvl 4 */
	{  5,  0  }, /* lvl 5 */
	{  6,  0  }, /* lvl 6 */
	{  7,  0  }, /* lvl 7 (only for high rssi) */
	{  8,  0  }  /* lvl 8 (only for high rssi) */
};

#define ATH9K_ANI_CCK_NUM_LEVEL \
	ARRAY_SIZE(cck_level_table)
#define ATH9K_ANI_CCK_MAX_LEVEL \
	(ATH9K_ANI_CCK_NUM_LEVEL-1)
#define ATH9K_ANI_CCK_MAX_LEVEL_LOW_RSSI \
	(ATH9K_ANI_CCK_NUM_LEVEL-3)
#define ATH9K_ANI_CCK_DEF_LEVEL \
	2 /* default level - matches the INI settings */

static void ath9k_hw_update_mibstats(struct ath_hw *ah,
				     struct ath9k_mib_stats *stats)
{
	u32 addr[5] = {AR_RTS_OK, AR_RTS_FAIL, AR_ACK_FAIL,
		       AR_FCS_FAIL, AR_BEACON_CNT};

Annotation

Implementation Notes