rt2x00: rt2800lib: use step-by-step frequency offset adjustment on MMIO devices

According to the DPO_RT5572_LinuxSTA_2.6.0.1_20120629
driver, the RFCSR17 register can't be programmed in
one step on devices which are using the frequency
offset adjustment code.

Update the code to use step-by-step adjustment.

Reference:
  RT30xxWriteRFRegister function in common/rt_rf.c

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c b/drivers/net/wireless/rt2x00/rt2800lib.c
index bebc56f..623ad9d 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/rt2x00/rt2800lib.c
@@ -2496,7 +2496,7 @@ static void rt2800_config_channel_rf3053(struct rt2x00_dev *rt2x00dev,
 
 static void rt2800_adjust_freq_offset(struct rt2x00_dev *rt2x00dev)
 {
-       u8 freq_offset;
+       u8 freq_offset, prev_freq_offset;
        u8 rfcsr, prev_rfcsr;
 
        freq_offset = rt2x00_get_field8(rt2x00dev->freq_offset, RFCSR17_CODE);
@@ -2509,11 +2509,24 @@ static void rt2800_adjust_freq_offset(struct rt2x00_dev *rt2x00dev)
        if (rfcsr == prev_rfcsr)
                return;
 
-       if (rt2x00_is_usb(rt2x00dev))
+       if (rt2x00_is_usb(rt2x00dev)) {
                rt2800_mcu_request(rt2x00dev, MCU_FREQ_OFFSET, 0xff,
                                   freq_offset, prev_rfcsr);
-       else
+               return;
+       }
+
+       prev_freq_offset = rt2x00_get_field8(prev_rfcsr, RFCSR17_CODE);
+       while (prev_freq_offset != freq_offset) {
+               if (prev_freq_offset < freq_offset)
+                       prev_freq_offset++;
+               else
+                       prev_freq_offset--;
+
+               rt2x00_set_field8(&rfcsr, RFCSR17_CODE, prev_freq_offset);
                rt2800_rfcsr_write(rt2x00dev, 17, rfcsr);
+
+               usleep_range(1000, 1500);
+       }
 }
 
 static void rt2800_config_channel_rf3290(struct rt2x00_dev *rt2x00dev,