[media] em28xx: fix+improve+unify i2c error handling, debug messages and code comments

- do not pass USB specific error codes to userspace/i2c-subsystem
- unify the returned error codes and make them compliant with
  the i2c subsystem spec
- check number of actually transferred bytes (via USB) everywehere
- fix/improve debug messages
- improve code comments

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
index 6916e87..80f87bb 100644 (file)
--- a/drivers/media/usb/em28xx/em28xx-core.c
+++ b/drivers/media/usb/em28xx/em28xx-core.c
@@ -101,7 +101,7 @@ int em28xx_read_reg_req_len(struct em28xx *dev, u8 req, u16 reg,
                if (reg_debug)
                        printk(" failed!\n");
                mutex_unlock(&dev->ctrl_urb_lock);
-               return ret;
+               return usb_translate_errors(ret);
        }
 
        if (len)
@@ -182,6 +182,9 @@ int em28xx_write_regs_req(struct em28xx *dev, u8 req, u16 reg, char *buf,
                              0x0000, reg, dev->urb_buf, len, HZ);
        mutex_unlock(&dev->ctrl_urb_lock);
 
+       if (ret < 0)
+               return usb_translate_errors(ret);
+
        if (dev->wait_after_write)
                msleep(dev->wait_after_write);
 

diff --git a/drivers/media/usb/em28xx/em28xx-i2c.c b/drivers/media/usb/em28xx/em28xx-i2c.c
index 4a24ed0..f784b51 100644 (file)
--- a/drivers/media/usb/em28xx/em28xx-i2c.c
+++ b/drivers/media/usb/em28xx/em28xx-i2c.c
@@ -76,18 +76,26 @@ static int em2800_i2c_send_bytes(struct em28xx *dev, u8 addr, u8 *buf, u16 len)
        /* trigger write */
        ret = dev->em28xx_write_regs(dev, 4 - len, &b2[4 - len], 2 + len);
        if (ret != 2 + len) {
-               em28xx_warn("writing to i2c device failed (error=%i)\n", ret);
-               return -EIO;
+               em28xx_warn("failed to trigger write to i2c address 0x%x "
+                           "(error=%i)\n", addr, ret);
+               return (ret < 0) ? ret : -EIO;
        }
        /* wait for completion */
        for (write_timeout = EM2800_I2C_XFER_TIMEOUT; write_timeout > 0;
             write_timeout -= 5) {
                ret = dev->em28xx_read_reg(dev, 0x05);
-               if (ret == 0x80 + len - 1)
+               if (ret == 0x80 + len - 1) {
                        return len;
+               } else if (ret == 0x94 + len - 1) {
+                       return -ENODEV;
+               } else if (ret < 0) {
+                       em28xx_warn("failed to get i2c transfer status from "
+                                   "bridge register (error=%i)\n", ret);
+                       return ret;
+               }
                msleep(5);
        }
-       em28xx_warn("i2c write timed out\n");
+       em28xx_warn("write to i2c device at 0x%x timed out\n", addr);
        return -EIO;
 }
 
@@ -168,24 +176,48 @@ static int em2800_i2c_check_for_device(struct em28xx *dev, u8 addr)
 static int em28xx_i2c_send_bytes(struct em28xx *dev, u16 addr, u8 *buf,
                                 u16 len, int stop)
 {
-       int wrcount = 0;
        int write_timeout, ret;
 
        if (len < 1 || len > 64)
                return -EOPNOTSUPP;
+       /* NOTE: limited by the USB ctrl message constraints
+        * Zero length reads always succeed, even if no device is connected */
 
-       wrcount = dev->em28xx_write_regs_req(dev, stop ? 2 : 3, addr, buf, len);
+       /* Write to i2c device */
+       ret = dev->em28xx_write_regs_req(dev, stop ? 2 : 3, addr, buf, len);
+       if (ret != len) {
+               if (ret < 0) {
+                       em28xx_warn("writing to i2c device at 0x%x failed "
+                                   "(error=%i)\n", addr, ret);
+                       return ret;
+               } else {
+                       em28xx_warn("%i bytes write to i2c device at 0x%x "
+                                   "requested, but %i bytes written\n",
+                                   len, addr, ret);
+                       return -EIO;
+               }
+       }
 
-       /* Seems to be required after a write */
+       /* Check success of the i2c operation */
        for (write_timeout = EM2800_I2C_XFER_TIMEOUT; write_timeout > 0;
             write_timeout -= 5) {
                ret = dev->em28xx_read_reg(dev, 0x05);
-               if (!ret)
-                       break;
+               if (ret == 0) { /* success */
+                       return len;
+               } else if (ret == 0x10) {
+                       return -ENODEV;
+               } else if (ret < 0) {
+                       em28xx_warn("failed to read i2c transfer status from "
+                                   "bridge (error=%i)\n", ret);
+                       return ret;
+               }
                msleep(5);
+               /* NOTE: do we really have to wait for success ?
+                  Never seen anything else than 0x00 or 0x10
+                  (even with high payload) ...                 */
        }
-
-       return wrcount;
+       em28xx_warn("write to i2c device at 0x%x timed out\n", addr);
+       return -EIO;
 }
 
 /*
@@ -198,15 +230,40 @@ static int em28xx_i2c_recv_bytes(struct em28xx *dev, u16 addr, u8 *buf, u16 len)
 
        if (len < 1 || len > 64)
                return -EOPNOTSUPP;
+       /* NOTE: limited by the USB ctrl message constraints
+        * Zero length reads always succeed, even if no device is connected */
 
+       /* Read data from i2c device */
        ret = dev->em28xx_read_reg_req_len(dev, 2, addr, buf, len);
+       if (ret != len) {
+               if (ret < 0) {
+                       em28xx_warn("reading from i2c device at 0x%x failed "
+                                   "(error=%i)\n", addr, ret);
+                       return ret;
+               } else {
+                       em28xx_warn("%i bytes requested from i2c device at "
+                                   "0x%x, but %i bytes received\n",
+                                   len, addr, ret);
+                       return -EIO;
+               }
+       }
+
+       /* Check success of the i2c operation */
+       ret = dev->em28xx_read_reg(dev, 0x05);
        if (ret < 0) {
-               em28xx_warn("reading i2c device failed (error=%i)\n", ret);
+               em28xx_warn("failed to read i2c transfer status from "
+                           "bridge (error=%i)\n", ret);
                return ret;
        }
-       if (dev->em28xx_read_reg(dev, 0x5) != 0)
-               return -ENODEV;
-       return ret;
+       if (ret > 0) {
+               if (ret == 0x10) {
+                       return -ENODEV;
+               } else {
+                       em28xx_warn("unknown i2c error (status=%i)\n", ret);
+                       return -EIO;
+               }
+       }
+       return len;
 }
 
 /*
@@ -216,15 +273,12 @@ static int em28xx_i2c_recv_bytes(struct em28xx *dev, u16 addr, u8 *buf, u16 len)
 static int em28xx_i2c_check_for_device(struct em28xx *dev, u16 addr)
 {
        int ret;
+       u8 buf;
 
-       ret = dev->em28xx_read_reg_req(dev, 2, addr);
-       if (ret < 0) {
-               em28xx_warn("reading from i2c device failed (error=%i)\n", ret);
-               return ret;
-       }
-       if (dev->em28xx_read_reg(dev, 0x5) != 0)
-               return -ENODEV;
-       return 0;
+       ret = em28xx_i2c_recv_bytes(dev, addr, &buf, 1);
+       if (ret == 1)
+               return 0;
+       return (ret < 0) ? ret : -EIO;
 }
 
 /*
@@ -249,11 +303,11 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
                                rc = em2800_i2c_check_for_device(dev, addr);
                        else
                                rc = em28xx_i2c_check_for_device(dev, addr);
-                       if (rc < 0) {
-                               dprintk2(2, " no device\n");
+                       if (rc == -ENODEV) {
+                               if (i2c_debug >= 2)
+                                       printk(" no device\n");
                                return rc;
                        }
-
                } else if (msgs[i].flags & I2C_M_RD) {
                        /* read bytes */
                        if (dev->board.is_em2800)
@@ -284,16 +338,16 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
                                                           msgs[i].len,
                                                           i == num - 1);
                }
-               if (rc < 0)
-                       goto err;
+               if (rc < 0) {
+                       if (i2c_debug >= 2)
+                               printk(" ERROR: %i\n", rc);
+                       return rc;
+               }
                if (i2c_debug >= 2)
                        printk("\n");
        }
 
        return num;
-err:
-       dprintk2(2, " ERROR: %i\n", rc);
-       return rc;
 }
 
 /* based on linux/sunrpc/svcauth.h and linux/hash.h