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Wolfson Microelectronics WM9705 and WM9712 Touchscreen Controllers
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Wolfson Microelectronics WM9705 and WM9712 Touchscreen Controllers
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===================================================================
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===================================================================
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The WM9705 and WM9712 are high performance AC97 audio codecs with built
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The WM9705 and WM9712 are high performance AC97 audio codecs with built
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in touchscreen controllers that are mainly found in portable devices.
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in touchscreen controllers that are mainly found in portable devices.
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i.e. Dell Axim and Toshiba e740.
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i.e. Dell Axim and Toshiba e740.
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This driver uses the AC97 link controller for all communication with the
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This driver uses the AC97 link controller for all communication with the
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codec and can be either built into the kernel or built as a module.
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codec and can be either built into the kernel or built as a module.
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Build Instructions
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Build Instructions
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==================
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==================
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The driver will be built into the kernel if "sound card support" = y and
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The driver will be built into the kernel if "sound card support" = y and
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"wolfson AC97 touchscreen support" = y in the kernel sound configuration.
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"wolfson AC97 touchscreen support" = y in the kernel sound configuration.
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To build as a module, "wolfson AC97 touchscreen support" = m
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To build as a module, "wolfson AC97 touchscreen support" = m
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in the kernel sound configuration.
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in the kernel sound configuration.
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Driver Features
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Driver Features
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===============
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===============
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* supports WM9705, WM9712
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* supports WM9705, WM9712
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* polling mode
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* polling mode
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* coordinate polling
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* coordinate polling
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* adjustable rpu/dpp settings
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* adjustable rpu/dpp settings
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* adjustable pressure current
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* adjustable pressure current
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* adjustable sample settle delay
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* adjustable sample settle delay
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* 4 and 5 wire touchscreens (5 wire is WM9712 only)
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* 4 and 5 wire touchscreens (5 wire is WM9712 only)
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* pen down detection
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* pen down detection
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* power management
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* power management
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* AUX ADC sampling
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* AUX ADC sampling
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Driver Usage
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Driver Usage
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============
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============
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In order to use this driver, a char device called wm97xx with a major
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In order to use this driver, a char device called wm97xx with a major
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number of 10 and minor number 16 will have to be created under
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number of 10 and minor number 16 will have to be created under
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/dev/touchscreen.
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/dev/touchscreen.
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e.g.
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e.g.
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mknod /dev/touchscreen/wm97xx c 10 16
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mknod /dev/touchscreen/wm97xx c 10 16
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Driver Parameters
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Driver Parameters
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=================
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=================
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The driver can accept several parameters for fine tuning the touchscreen.
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The driver can accept several parameters for fine tuning the touchscreen.
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However, the syntax is different between module options and passing the
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However, the syntax is different between module options and passing the
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options in the kernel command line.
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options in the kernel command line.
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e.g.
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e.g.
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rpu=1 (module)
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rpu=1 (module)
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rpu:1 (kernel command line)
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rpu:1 (kernel command line)
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1. Codec sample mode. (mode)
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1. Codec sample mode. (mode)
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The WM9712 can sample touchscreen data in 3 different operating
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The WM9712 can sample touchscreen data in 3 different operating
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modes. i.e. polling, coordinate and continous.
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modes. i.e. polling, coordinate and continous.
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Polling:- The driver polls the codec and issues 3 seperate commands
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Polling:- The driver polls the codec and issues 3 seperate commands
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over the AC97 link to read X,Y and pressure.
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over the AC97 link to read X,Y and pressure.
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Coordinate: - The driver polls the codec and only issues 1 command over
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Coordinate: - The driver polls the codec and only issues 1 command over
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the AC97 link to read X,Y and pressure. This mode has
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the AC97 link to read X,Y and pressure. This mode has
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strict timing requirements and may drop samples if
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strict timing requirements and may drop samples if
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interrupted. However, it is less demanding on the AC97
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interrupted. However, it is less demanding on the AC97
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link. Note: this mode requires a larger delay than polling
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link. Note: this mode requires a larger delay than polling
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mode.
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mode.
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Continuous:- The codec automatically samples X,Y and pressure and then
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Continuous:- The codec automatically samples X,Y and pressure and then
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sends the data over the AC97 link in slots. This is then
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sends the data over the AC97 link in slots. This is then
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same method used by the codec when recording audio.
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same method used by the codec when recording audio.
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Set mode = 0 for polling, 1 for coordinate and 2 for continuous.
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Set mode = 0 for polling, 1 for coordinate and 2 for continuous.
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Default mode = 0
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Default mode = 0
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2. WM9712 Internal pull up for pen detect. (rpu)
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2. WM9712 Internal pull up for pen detect. (rpu)
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Pull up is in the range 1.02k (least sensitive) to 64k (most sensitive)
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Pull up is in the range 1.02k (least sensitive) to 64k (most sensitive)
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i.e. pull up resistance = 64k Ohms / rpu.
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i.e. pull up resistance = 64k Ohms / rpu.
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Adjust this value if you are having problems with pen detect not
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Adjust this value if you are having problems with pen detect not
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detecting any down events.
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detecting any down events.
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Set rpu = value
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Set rpu = value
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Default rpu = 1
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Default rpu = 1
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3. WM9705 Pen detect comparator threshold. (pdd)
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3. WM9705 Pen detect comparator threshold. (pdd)
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0 to Vmid in 15 steps, 0 = use zero power comparator with Vmid threshold
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0 to Vmid in 15 steps, 0 = use zero power comparator with Vmid threshold
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i.e. 1 = Vmid/15 threshold
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i.e. 1 = Vmid/15 threshold
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15 = Vmid/1 threshold
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15 = Vmid/1 threshold
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Adjust this value if you are having problems with pen detect not
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Adjust this value if you are having problems with pen detect not
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detecting any down events.
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detecting any down events.
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Set pdd = value
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Set pdd = value
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Default pdd = 0
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Default pdd = 0
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4. Set current used for pressure measurement. (pil)
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4. Set current used for pressure measurement. (pil)
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Set pil = 2 to use 400uA
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Set pil = 2 to use 400uA
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pil = 1 to use 200uA and
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pil = 1 to use 200uA and
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pil = 0 to disable pressure measurement.
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pil = 0 to disable pressure measurement.
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This is used to increase the range of values returned by the adc
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This is used to increase the range of values returned by the adc
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when measureing touchpanel pressure.
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when measureing touchpanel pressure.
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Default pil = 0
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Default pil = 0
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5. WM9712 Set 5 wire touchscreen mode. (five_wire)
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5. WM9712 Set 5 wire touchscreen mode. (five_wire)
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Set five_wire = 1 to enable 5 wire mode on the WM9712.
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Set five_wire = 1 to enable 5 wire mode on the WM9712.
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Default five_wire = 0
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Default five_wire = 0
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NOTE: Five wire mode does not allow for readback of pressure.
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NOTE: Five wire mode does not allow for readback of pressure.
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6. ADC sample delay. (delay)
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6. ADC sample delay. (delay)
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For accurate touchpanel measurements, some settling time may be
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For accurate touchpanel measurements, some settling time may be
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required between the switch matrix applying a voltage across the
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required between the switch matrix applying a voltage across the
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touchpanel plate and the ADC sampling the signal.
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touchpanel plate and the ADC sampling the signal.
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This delay can be set by setting delay = n, where n is the array
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This delay can be set by setting delay = n, where n is the array
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position of the delay in the array delay_table below.
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position of the delay in the array delay_table below.
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Long delays > 1ms are supported for completeness, but are not
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Long delays > 1ms are supported for completeness, but are not
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recommended.
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recommended.
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Default delay = 4
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Default delay = 4
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wm_delay uS AC97 link frames
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wm_delay uS AC97 link frames
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====================================
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====================================
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0 21 1
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0 21 1
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1 42 2
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1 42 2
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2 84 4
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2 84 4
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3 167 8
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3 167 8
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4 333 16
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4 333 16
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5 667 32
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5 667 32
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6 1000 48
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6 1000 48
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7 1333 64
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7 1333 64
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8 2000 96
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8 2000 96
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9 2667 128
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9 2667 128
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10 3333 160
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10 3333 160
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11 4000 192
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11 4000 192
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12 4667 224
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12 4667 224
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13 5333 256
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13 5333 256
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14 6000 288
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14 6000 288
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15 0 0 (No delay, switch matrix always on)
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15 0 0 (No delay, switch matrix always on)
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Contact
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Contact
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=======
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=======
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Further information about the WM9705 and WM9712 can be found on the
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Further information about the WM9705 and WM9712 can be found on the
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Wolfson Website. http://www.wolfsonmicro.com
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Wolfson Website. http://www.wolfsonmicro.com
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Please report bugs to liam.girdwood@wolfsonmicro.com or
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Please report bugs to liam.girdwood@wolfsonmicro.com or
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linux@wolfsonmicro.com
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linux@wolfsonmicro.com
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