Many staticcheck fixes

It now passes when run as:
  staticcheck -checks all,-U1000,-ST1003,-SA5002,-SA1019 ./...

The disabled checks will be enabled later since they are less trivial to
enable, as this is already a non-trivial number of modifications.

cmd/bmxx80/main.go

@@ -56,7 +56,7 @@ func run(dev physic.SenseEnv, interval time.Duration) error {
 	if err != nil {
 		return err
 	}
-	chanSignal := make(chan os.Signal)
+	chanSignal := make(chan os.Signal, 1)
 	signal.Notify(chanSignal, os.Interrupt)
 	for {
 		select {

cmd/cap1xxx/main.go

@@ -41,7 +41,7 @@ func mainImpl() error {
 
 	opts := cap1xxx.DefaultOpts
 	if *i2cAddr != 0 {
-		if *i2cAddr < 0 || *i2cAddr > 65535 {
+		if *i2cAddr > 65535 {
 			return errors.New("invlaid -i2c value")
 		}
 		opts.I2CAddr = uint16(*i2cAddr)

cmd/ir/main.go

@@ -42,7 +42,7 @@ func mainImpl() error {
 	}
 	c := i.Channel()
 
-	ctrlC := make(chan os.Signal)
+	ctrlC := make(chan os.Signal, 1)
 	signal.Notify(ctrlC, os.Interrupt)
 
 	first := true

conn/display/display.go

@@ -41,6 +41,6 @@ type Drawer interface {
 	// update.
 	//
 	// srcPts aligns the image at this offset, enabling using a subset of the
-	// source image. use image.ZP/image.Point{} to take the image at its origin.
+	// source image. use image.Point{} to take the image at its origin.
 	Draw(dstRect image.Rectangle, src image.Image, srcPts image.Point) error
 }

conn/display/example_test.go

@@ -28,9 +28,9 @@ func ExampleDrawer() {
 
 	// Render the image. The normal use case is:
 	// - Use d.Bounds() as the dstRect, to cover the whole screen.
-	// - Use image.ZP/image.Point{} as 'srcPts' unless you want to offset inside
+	// - Use image.Point{} as 'srcPts' unless you want to offset inside
 	//   the image.
-	if err := d.Draw(d.Bounds(), img, image.ZP); err != nil {
+	if err := d.Draw(d.Bounds(), img, image.Point{}); err != nil {
 		log.Fatal(err)
 	}
 }

conn/gpio/gpiotest/gpiotest_test.go

@@ -137,7 +137,7 @@ func TestLogPinIO(t *testing.T) {
 }
 
 func TestAll(t *testing.T) {
-	if 2 != len(gpioreg.All()) {
+	if len(gpioreg.All()) != 2 {
 		t.Fatal("expected two pins registered for test")
 	}
 }

conn/physic/units.go

@@ -1923,12 +1923,10 @@ func dtoi(d decimal, scale int) (int64, bool) {
 	switch {
 	case d.exp+scale < 0:
 		u = (u + powerOf10[mag]/2) / powerOf10[mag]
-		break
 	case mag == 0:
 		if u > maxInt64 {
 			return 0, true
 		}
-		break
 	default:
 		check := u * powerOf10[mag]
 		if check/powerOf10[mag] != u || check > maxInt64 {
@@ -2020,7 +2018,6 @@ func atod(s string) (decimal, int, error) {
 				return decimal{}, 0, &parseError{errNotANumber}
 			}
 			end = i
-			break
 		}
 	}
 

conn/pin/pinreg/pinreg.go

@@ -43,7 +43,7 @@ func All() map[string][][]pin.Pin {
 func Position(p pin.Pin) (string, int) {
 	mu.Lock()
 	defer mu.Unlock()
-	pos, _ := byPin[realPin(p).Name()]
+	pos := byPin[realPin(p).Name()]
 	return pos.name, pos.number
 }
 

devices/lepton/internal/internal.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
+// Package internal contains code shared between cci and lepton.
 package internal
 
 import (

devices/lepton/lepton.go

@@ -146,11 +146,13 @@ func (d *Dev) NextFrame(f *Frame) error {
 		if err := d.readFrame(f); err != nil {
 			return err
 		}
-		if f.Metadata.FFCDesired {
-			// TODO(maruel): Automatically trigger FFC when applicable, only do if
-			// the camera has a shutter.
-			//go d.RunFFC()
-		}
+		/*
+			if f.Metadata.FFCDesired {
+				// TODO(maruel): Automatically trigger FFC when applicable, only do if
+				// the camera has a shutter.
+				go d.RunFFC()
+			}
+		*/
 		// Sadly the Lepton will unconditionally send 27fps, even if the effective
 		// rate is 9fps.
 		if !equalUint16(d.prevImg.Pix, f.Gray14.Pix) {

experimental/cmd/as7262/main.go

@@ -9,6 +9,8 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
 	"time"
 
 	"periph.io/x/periph/conn/i2c/i2creg"
@@ -46,6 +48,9 @@ func mainImpl() error {
 	defer sensor.Halt()
 
 	fmt.Println("ctrl+c to quit")
+	var halt = make(chan os.Signal, 1)
+	signal.Notify(halt, syscall.SIGTERM)
+	signal.Notify(halt, syscall.SIGINT)
 
 	senseTime := time.Millisecond * 300
 
@@ -57,6 +62,8 @@ func mainImpl() error {
 				return fmt.Errorf("sensor reading error: %v", err)
 			}
 			fmt.Println(spectrum)
+		case <-halt:
+			return nil
 		}
 	}
 }

experimental/cmd/hd44780/main.go

@@ -51,7 +51,7 @@ func mainFunc() error {
 		return fmt.Errorf("register select pin %s can not be found", *rsPin)
 	}
 	ePinReg := gpioreg.ByName(*ePin)
-	if ePin == nil {
+	if ePinReg == nil {
 		return fmt.Errorf("strobe pin %s can not be found", *ePin)
 	}
 

experimental/cmd/hx711/main.go

@@ -45,7 +45,7 @@ func mainFunc() error {
 		return fmt.Errorf("clock pin %s can not be found", *clkPin)
 	}
 	dataPinReg := gpioreg.ByName(*dataPin)
-	if dataPin == nil {
+	if dataPinReg == nil {
 		return fmt.Errorf("data pin %s can not be found", *dataPin)
 	}
 

experimental/cmd/ina219/main.go

@@ -48,7 +48,7 @@ func mainImpl() error {
 
 	// Read values from sensor every second.
 	everySecond := time.NewTicker(time.Second).C
-	var halt = make(chan os.Signal)
+	var halt = make(chan os.Signal, 1)
 	signal.Notify(halt, syscall.SIGTERM)
 	signal.Notify(halt, syscall.SIGINT)
 

experimental/cmd/inky/inky.go

@@ -92,5 +92,5 @@ func mainImpl() error {
 	}
 
 	log.Printf("Drawing image...")
-	return dev.Draw(img.Bounds(), img, image.ZP)
+	return dev.Draw(img.Bounds(), img, image.Point{})
 }

experimental/cmd/mcp9808/main.go

@@ -47,7 +47,7 @@ func mainImpl() error {
 
 	// Read values from sensor every second.
 	everySecond := time.Tick(time.Second)
-	var halt = make(chan os.Signal)
+	var halt = make(chan os.Signal, 1)
 	signal.Notify(halt, syscall.SIGTERM)
 	signal.Notify(halt, syscall.SIGINT)
 

experimental/conn/gpio/gpioutil/debounce.go

@@ -67,10 +67,7 @@ func (d *debounced) Read() gpio.Level {
 //
 // It is the smoothed out value from the underlying gpio.PinIO.
 func (d *debounced) WaitForEdge(timeout time.Duration) bool {
-	if !d.PinIO.WaitForEdge(timeout) {
-		return false
-	}
-	return true
+	return d.PinIO.WaitForEdge(timeout)
 }
 
 // Halt implements gpio.PinIO.

experimental/conn/gpio/gpioutil/polledge_test.go

@@ -46,7 +46,7 @@ func TestPollEdge_Halt(t *testing.T) {
 		// inside WaitForEdge().
 		<-f.wait
 		if err := p.Halt(); err != nil {
-			t.Fatal(err)
+			t.Error(err)
 		}
 	}()
 	// p.die triggers.

experimental/devices/as7262/as7262.go

@@ -240,12 +240,12 @@ func (d *Dev) Halt() error {
 	d.cancel()
 	// A receive can always proceed on a closed channel we can use that
 	// to signal that the running process has been canceled correctly.
-	_, _ = <-d.done
+	<-d.done
 	return nil
 }
 
 func (d *Dev) String() string {
-	return fmt.Sprintf("AMS AS7262 6 channel visible spectrum sensor")
+	return "AMS AS7262 6 channel visible spectrum sensor"
 }
 
 // Gain is the sensor gain for all bands

experimental/devices/ina219/ina219smoketest/ina219smoketest.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
+// Package ina219smoketest tests the ina219 device.
 package ina219smoketest
 
 import (

experimental/devices/inky/example_test.go

@@ -54,7 +54,7 @@ func Example() {
 		log.Fatal(err)
 	}
 
-	if err := dev.Draw(img.Bounds(), img, image.ZP); err != nil {
+	if err := dev.Draw(img.Bounds(), img, image.Point{}); err != nil {
 		log.Fatal(err)
 	}
 }

experimental/devices/inky/inky.go

@@ -57,7 +57,7 @@ func (c *Color) Set(s string) error {
 	case "white":
 		*c = White
 	default:
-		return fmt.Errorf("Unknown color %q: expected either black, red, yellow or white", s)
+		return fmt.Errorf("unknown color %q: expected either black, red, yellow or white", s)
 	}
 	return nil
 }
@@ -90,7 +90,7 @@ func (m *Model) Set(s string) error {
 	case "WHAT":
 		*m = WHAT
 	default:
-		return fmt.Errorf("Unknown model %q: expected either PHAT or WHAT", s)
+		return fmt.Errorf("unknown model %q: expected either PHAT or WHAT", s)
 	}
 	return nil
 }
@@ -278,7 +278,7 @@ func (d *Dev) Draw(dstRect image.Rectangle, src image.Image, srcPtrs image.Point
 
 // DrawAll redraws the whole display.
 func (d *Dev) DrawAll(src image.Image) error {
-	return d.Draw(d.Bounds(), src, image.ZP)
+	return d.Draw(d.Bounds(), src, image.Point{})
 }
 
 func (d *Dev) update(border byte, black []byte, red []byte) (err error) {

experimental/devices/mcp23xxx/registers.go

@@ -107,5 +107,5 @@ func (r *registerCache) getAndSetBit(bit uint8, value bool, cached bool) error {
 
 func (r *registerCache) getBit(bit uint8, cached bool) (bool, error) {
 	v, err := r.readValue(cached)
-	return 0 != (v & (1 << bit)), err
+	return (v & (1 << bit)) != 0, err
 }

experimental/devices/mcp9808/mcp9808smoketest/mcp9808smoketest.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
+// Package mcp9808smoketest implements a smoke test for the mcp9808.
 package mcp9808smoketest
 
 import (

experimental/devices/mpu9250/accelerometer/accelerometer.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
+// Package accelerometer contains constants for the MPU9250.
 package accelerometer
 
 // Valid accelerator values.

experimental/devices/mpu9250/reg/reg.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
+// Package reg defines constants for the MPU9250.
 package reg
 
 // Unsorted mix of register addresses, commands and constants.

experimental/devices/pca9685/pca9685_test.go

@@ -125,7 +125,7 @@ func TestPCA9685(t *testing.T) {
 
 func TestPCA9685_invalidCh(t *testing.T) {
 	scenario := &i2ctest.Playback{
-		Ops: append(initializationSequence()),
+		Ops: initializationSequence(),
 	}
 
 	dev, err := NewI2C(scenario, I2CAddr)

experimental/devices/unicornhd/unicornhd.go

@@ -60,7 +60,7 @@ func (device *Dev) String() string {
 // Halt sets all the pixels to black. Error is always nil.
 func (device *Dev) Halt() error {
 	black := color.RGBA{0, 0, 0, 0}
-	return device.Draw(device.Bounds(), &image.Uniform{black}, image.ZP)
+	return device.Draw(device.Bounds(), &image.Uniform{black}, image.Point{})
 }
 
 // ColorModel implements devices.Display. There's no surprise, it is

experimental/devices/unicornhd/unicornhd_test.go

@@ -164,7 +164,7 @@ func TestDrawWritesBlackImageToSpi(t *testing.T) {
 	buf := bytes.Buffer{}
 	dev, _ := New(spitest.NewRecordRaw(&buf))
 	black := color.RGBA{0, 0, 0, 0}
-	if err := dev.Draw(dev.Bounds(), &image.Uniform{black}, image.ZP); err != nil {
+	if err := dev.Draw(dev.Bounds(), &image.Uniform{black}, image.Point{}); err != nil {
 		t.Fatal(err)
 	}
 
@@ -219,7 +219,7 @@ func TestDrawWritesWhiteImageToSpi(t *testing.T) {
 	buf := bytes.Buffer{}
 	dev, _ := New(spitest.NewRecordRaw(&buf))
 	white := color.RGBA{255, 255, 255, 255}
-	if err := dev.Draw(dev.Bounds(), &image.Uniform{white}, image.ZP); err != nil {
+	if err := dev.Draw(dev.Bounds(), &image.Uniform{white}, image.Point{}); err != nil {
 		t.Fatal(err)
 	}
 
@@ -291,7 +291,7 @@ func TestDrawWritesSequenceImageToSpi(t *testing.T) {
 			img.Set(x, y, clr)
 		}
 	}
-	if err := dev.Draw(dev.Bounds(), img, image.ZP); err != nil {
+	if err := dev.Draw(dev.Bounds(), img, image.Point{}); err != nil {
 		t.Fatal(err)
 	}
 
@@ -354,7 +354,7 @@ func TestDrawSupportsPartialUpdates(t *testing.T) {
 	buf := bytes.Buffer{}
 	dev, _ := New(spitest.NewRecordRaw(&buf))
 	white := color.RGBA{0xFF, 0xFF, 0xFF, 0xFF}
-	if err := dev.Draw(image.Rect(0, 0, 3, 3), &image.Uniform{white}, image.ZP); err != nil {
+	if err := dev.Draw(image.Rect(0, 0, 3, 3), &image.Uniform{white}, image.Point{}); err != nil {
 		t.Fatal(err)
 	}
 

experimental/host/mt7688/driver.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
+// Package mt7688 interfaces with the MediaTek MT7688 MIPS CPU used on low cost board.
 package mt7688
 
 import (

host/allwinner/gpio.go

@@ -994,7 +994,7 @@ func (d *driverGPIO) After() []string {
 // for the exact processor model detected.
 func (d *driverGPIO) Init() (bool, error) {
 	if !Present() {
-		return false, errors.New("Allwinner CPU not detected")
+		return false, errors.New("no Allwinner CPU detected")
 	}
 
 	// Mark the right pins as available even if the memory map fails so they can

host/allwinner/gpio_pl.go

@@ -478,7 +478,7 @@ func (d *driverGPIOPL) After() []string {
 func (d *driverGPIOPL) Init() (bool, error) {
 	// BUG(maruel): H3 supports group PL too.
 	if !IsA64() {
-		return false, errors.New("A64 CPU not detected")
+		return false, errors.New("no A64 CPU detected")
 	}
 
 	// Mark the right pins as available even if the memory map fails so they can