diff mbox

[v1] HID: cp2112: support i2c write-read transfers in hid-cp2112

Message ID 1434621340-10422-1-git-send-email-ellen@cumulusnetworks.com
State Superseded
Headers show

Commit Message

Ellen Wang June 18, 2015, 9:55 a.m. UTC 
cp2112_i2c_xfer() only supports a single i2c_msg.  More than
one message at a time just returns EIO.  This breaks certain
important cases.  For example, the at24 eeprom driver generates
paired write and read messages (for eeprom address and data).

Since the device doesn't support i2c repeated starts in general,
but does support a single write-repeated-start-read pair
(since hardware rev 1), we recognize the latter case and
implement only that.

Signed-off-by: Ellen Wang <ellen@cumulusnetworks.com>
---
 drivers/hid/hid-cp2112.c |   74 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 55 insertions(+), 19 deletions(-)

Comments

Antonio Borneo June 20, 2015, 3:41 p.m. UTC | #1 
On Thu, Jun 18, 2015 at 5:55 PM, Ellen Wang <ellen@cumulusnetworks.com> wrote:
> cp2112_i2c_xfer() only supports a single i2c_msg.  More than
> one message at a time just returns EIO.  This breaks certain
> important cases.  For example, the at24 eeprom driver generates
> paired write and read messages (for eeprom address and data).
>
> Since the device doesn't support i2c repeated starts in general,
> but does support a single write-repeated-start-read pair
> (since hardware rev 1), we recognize the latter case and
> implement only that.

Hi Ellen,

I have ordered some device rev2, but shipment will take 2 weeks.
Do you mind if I delay testing this patch till I get them?

In mean time, one comment below.

> Signed-off-by: Ellen Wang <ellen@cumulusnetworks.com>
> ---
>  drivers/hid/hid-cp2112.c |   74 ++++++++++++++++++++++++++++++++++------------
>  1 file changed, 55 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
> index 5a72819..00d062a 100644
> --- a/drivers/hid/hid-cp2112.c
> +++ b/drivers/hid/hid-cp2112.c
> @@ -153,6 +153,7 @@ MODULE_DEVICE_TABLE(hid, cp2112_devices);
>  struct cp2112_device {
>         struct i2c_adapter adap;
>         struct hid_device *hdev;
> +       int hwversion;

No need for int; u8 is enough (value is copyed from buf[2] that is u8).
Put the new u8 field few lines below, together with the other u8, to
avoid extra padding.

No need to send immediately a new version. Let's see if there is any
other comment and if someone can test it before me.

Thanks,
Antonio

>         wait_queue_head_t wait;
>         u8 read_data[61];
>         u8 read_length;
> @@ -444,6 +445,24 @@ static int cp2112_i2c_write_req(void *buf, u8 slave_address, u8 *data,
>         return data_length + 3;
>  }
>
> +static int cp2112_i2c_write_read_req(void *buf, u8 slave_address,
> +                                    u8 *addr, int addr_length,
> +                                    int read_length)
> +{
> +       struct cp2112_write_read_req_report *report = buf;
> +
> +       if (read_length < 1 || read_length > 512 ||
> +           addr_length > sizeof(report->target_address))
> +               return -EINVAL;
> +
> +       report->report = CP2112_DATA_WRITE_READ_REQUEST;
> +       report->slave_address = slave_address << 1;
> +       report->length = cpu_to_be16(read_length);
> +       report->target_address_length = addr_length;
> +       memcpy(report->target_address, addr, addr_length);
> +       return addr_length + 5;
> +}
> +
>  static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>                            int num)
>  {
> @@ -451,26 +470,46 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>         struct hid_device *hdev = dev->hdev;
>         u8 buf[64];
>         ssize_t count;
> +       ssize_t read_length = 0;
> +       u8 *read_buf = NULL;
>         unsigned int retries;
>         int ret;
>
>         hid_dbg(hdev, "I2C %d messages\n", num);
>
> -       if (num != 1) {
> +       if (num == 1) {
> +               if (msgs->flags & I2C_M_RD) {
> +                       hid_dbg(hdev, "I2C read %#04x len %d\n",
> +                               msgs->addr, msgs->len);
> +                       read_length = msgs->len;
> +                       read_buf = msgs->buf;
> +                       count = cp2112_read_req(buf, msgs->addr, msgs->len);
> +               } else {
> +                       hid_dbg(hdev, "I2C write %#04x len %d\n",
> +                               msgs->addr, msgs->len);
> +                       count = cp2112_i2c_write_req(buf, msgs->addr,
> +                                                    msgs->buf, msgs->len);
> +               }
> +               if (count < 0)
> +                       return count;
> +       } else if (dev->hwversion > 1 &&  /* no repeated start in rev 1 */
> +                  num == 2 &&
> +                  msgs[0].addr == msgs[1].addr &&
> +                  !(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD)) {
> +               hid_dbg(hdev, "I2C write-read %#04x wlen %d rlen %d\n",
> +                       msgs[0].addr, msgs[0].len, msgs[1].len);
> +               read_length = msgs[1].len;
> +               read_buf = msgs[1].buf;
> +               count = cp2112_i2c_write_read_req(buf, msgs[0].addr,
> +                               msgs[0].buf, msgs[0].len, msgs[1].len);
> +               if (count < 0)
> +                       return count;
> +       } else {
>                 hid_err(hdev,
>                         "Multi-message I2C transactions not supported\n");
>                 return -EOPNOTSUPP;
>         }
>
> -       if (msgs->flags & I2C_M_RD)
> -               count = cp2112_read_req(buf, msgs->addr, msgs->len);
> -       else
> -               count = cp2112_i2c_write_req(buf, msgs->addr, msgs->buf,
> -                                            msgs->len);
> -
> -       if (count < 0)
> -               return count;
> -
>         ret = hid_hw_power(hdev, PM_HINT_FULLON);
>         if (ret < 0) {
>                 hid_err(hdev, "power management error: %d\n", ret);
> @@ -506,15 +545,12 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>                 goto power_normal;
>         }
>
> -       if (!(msgs->flags & I2C_M_RD))
> -               goto finish;
> -
> -       for (count = 0; count < msgs->len;) {
> -               ret = cp2112_read(dev, msgs->buf + count, msgs->len - count);
> +       for (count = 0; count < read_length;) {
> +               ret = cp2112_read(dev, read_buf + count, read_length - count);
>                 if (ret < 0)
>                         goto power_normal;
>                 count += ret;
> -               if (count > msgs->len) {
> +               if (count > read_length) {
>                         /*
>                          * The hardware returned too much data.
>                          * This is mostly harmless because cp2112_read()
> @@ -524,15 +560,14 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>                          * it shouldn't go unnoticed.
>                          */
>                         hid_err(hdev, "long read: %d > %zd\n",
> -                               ret, msgs->len - count + ret);
> +                               ret, read_length - count + ret);
>                         ret = -EIO;
>                         goto power_normal;
>                 }
>         }
>
> -finish:
>         /* return the number of transferred messages */
> -       ret = 1;
> +       ret = num;
>
>  power_normal:
>         hid_hw_power(hdev, PM_HINT_NORMAL);
> @@ -1040,6 +1075,7 @@ static int cp2112_probe(struct hid_device *hdev, const struct hid_device_id *id)
>         dev->adap.dev.parent    = &hdev->dev;
>         snprintf(dev->adap.name, sizeof(dev->adap.name),
>                  "CP2112 SMBus Bridge on hiddev%d", hdev->minor);
> +       dev->hwversion = buf[2];
>         init_waitqueue_head(&dev->wait);
>
>         hid_device_io_start(hdev);
> --
> 1.7.10.4
>
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Ellen Wang July 1, 2015, 8:09 a.m. UTC | #2 
In-line replies below:

On 06/20/2015 08:41 AM, Antonio Borneo wrote:
> On Thu, Jun 18, 2015 at 5:55 PM, Ellen Wang <ellen@cumulusnetworks.com> wrote:
>> cp2112_i2c_xfer() only supports a single i2c_msg.  More than
>> one message at a time just returns EIO.  This breaks certain
>> important cases.  For example, the at24 eeprom driver generates
>> paired write and read messages (for eeprom address and data).
>>
>> Since the device doesn't support i2c repeated starts in general,
>> but does support a single write-repeated-start-read pair
>> (since hardware rev 1), we recognize the latter case and
>> implement only that.
>
> Hi Ellen,
>
> I have ordered some device rev2, but shipment will take 2 weeks.
> Do you mind if I delay testing this patch till I get them?
>
> In mean time, one comment below.
>
>> Signed-off-by: Ellen Wang <ellen@cumulusnetworks.com>
>> ---
>>   drivers/hid/hid-cp2112.c |   74 ++++++++++++++++++++++++++++++++++------------
>>   1 file changed, 55 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
>> index 5a72819..00d062a 100644
>> --- a/drivers/hid/hid-cp2112.c
>> +++ b/drivers/hid/hid-cp2112.c
>> @@ -153,6 +153,7 @@ MODULE_DEVICE_TABLE(hid, cp2112_devices);
>>   struct cp2112_device {
>>          struct i2c_adapter adap;
>>          struct hid_device *hdev;
>> +       int hwversion;
>
> No need for int; u8 is enough (value is copyed from buf[2] that is u8).
> Put the new u8 field few lines below, together with the other u8, to
> avoid extra padding.

I know.  It's a matter of taste whether to use a natural type or a 
size-specific size.  I perfectly fine using u8 to save 4 bytes.

> No need to send immediately a new version. Let's see if there is any
> other comment and if someone can test it before me.
>
> Thanks,
> Antonio

Thanks!

>>          wait_queue_head_t wait;
>>          u8 read_data[61];
>>          u8 read_length;
>> @@ -444,6 +445,24 @@ static int cp2112_i2c_write_req(void *buf, u8 slave_address, u8 *data,
>>          return data_length + 3;
>>   }
>>
>> +static int cp2112_i2c_write_read_req(void *buf, u8 slave_address,
>> +                                    u8 *addr, int addr_length,
>> +                                    int read_length)
>> +{
>> +       struct cp2112_write_read_req_report *report = buf;
>> +
>> +       if (read_length < 1 || read_length > 512 ||
>> +           addr_length > sizeof(report->target_address))
>> +               return -EINVAL;
>> +
>> +       report->report = CP2112_DATA_WRITE_READ_REQUEST;
>> +       report->slave_address = slave_address << 1;
>> +       report->length = cpu_to_be16(read_length);
>> +       report->target_address_length = addr_length;
>> +       memcpy(report->target_address, addr, addr_length);
>> +       return addr_length + 5;
>> +}
>> +
>>   static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>>                             int num)
>>   {
>> @@ -451,26 +470,46 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>>          struct hid_device *hdev = dev->hdev;
>>          u8 buf[64];
>>          ssize_t count;
>> +       ssize_t read_length = 0;
>> +       u8 *read_buf = NULL;
>>          unsigned int retries;
>>          int ret;
>>
>>          hid_dbg(hdev, "I2C %d messages\n", num);
>>
>> -       if (num != 1) {
>> +       if (num == 1) {
>> +               if (msgs->flags & I2C_M_RD) {
>> +                       hid_dbg(hdev, "I2C read %#04x len %d\n",
>> +                               msgs->addr, msgs->len);
>> +                       read_length = msgs->len;
>> +                       read_buf = msgs->buf;
>> +                       count = cp2112_read_req(buf, msgs->addr, msgs->len);
>> +               } else {
>> +                       hid_dbg(hdev, "I2C write %#04x len %d\n",
>> +                               msgs->addr, msgs->len);
>> +                       count = cp2112_i2c_write_req(buf, msgs->addr,
>> +                                                    msgs->buf, msgs->len);
>> +               }
>> +               if (count < 0)
>> +                       return count;
>> +       } else if (dev->hwversion > 1 &&  /* no repeated start in rev 1 */
>> +                  num == 2 &&
>> +                  msgs[0].addr == msgs[1].addr &&
>> +                  !(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD)) {
>> +               hid_dbg(hdev, "I2C write-read %#04x wlen %d rlen %d\n",
>> +                       msgs[0].addr, msgs[0].len, msgs[1].len);
>> +               read_length = msgs[1].len;
>> +               read_buf = msgs[1].buf;
>> +               count = cp2112_i2c_write_read_req(buf, msgs[0].addr,
>> +                               msgs[0].buf, msgs[0].len, msgs[1].len);
>> +               if (count < 0)
>> +                       return count;
>> +       } else {
>>                  hid_err(hdev,
>>                          "Multi-message I2C transactions not supported\n");
>>                  return -EOPNOTSUPP;
>>          }
>>
>> -       if (msgs->flags & I2C_M_RD)
>> -               count = cp2112_read_req(buf, msgs->addr, msgs->len);
>> -       else
>> -               count = cp2112_i2c_write_req(buf, msgs->addr, msgs->buf,
>> -                                            msgs->len);
>> -
>> -       if (count < 0)
>> -               return count;
>> -
>>          ret = hid_hw_power(hdev, PM_HINT_FULLON);
>>          if (ret < 0) {
>>                  hid_err(hdev, "power management error: %d\n", ret);
>> @@ -506,15 +545,12 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>>                  goto power_normal;
>>          }
>>
>> -       if (!(msgs->flags & I2C_M_RD))
>> -               goto finish;
>> -
>> -       for (count = 0; count < msgs->len;) {
>> -               ret = cp2112_read(dev, msgs->buf + count, msgs->len - count);
>> +       for (count = 0; count < read_length;) {
>> +               ret = cp2112_read(dev, read_buf + count, read_length - count);
>>                  if (ret < 0)
>>                          goto power_normal;
>>                  count += ret;
>> -               if (count > msgs->len) {
>> +               if (count > read_length) {
>>                          /*
>>                           * The hardware returned too much data.
>>                           * This is mostly harmless because cp2112_read()
>> @@ -524,15 +560,14 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>>                           * it shouldn't go unnoticed.
>>                           */
>>                          hid_err(hdev, "long read: %d > %zd\n",
>> -                               ret, msgs->len - count + ret);
>> +                               ret, read_length - count + ret);
>>                          ret = -EIO;
>>                          goto power_normal;
>>                  }
>>          }
>>
>> -finish:
>>          /* return the number of transferred messages */
>> -       ret = 1;
>> +       ret = num;
>>
>>   power_normal:
>>          hid_hw_power(hdev, PM_HINT_NORMAL);
>> @@ -1040,6 +1075,7 @@ static int cp2112_probe(struct hid_device *hdev, const struct hid_device_id *id)
>>          dev->adap.dev.parent    = &hdev->dev;
>>          snprintf(dev->adap.name, sizeof(dev->adap.name),
>>                   "CP2112 SMBus Bridge on hiddev%d", hdev->minor);
>> +       dev->hwversion = buf[2];
>>          init_waitqueue_head(&dev->wait);
>>
>>          hid_device_io_start(hdev);
>> --
>> 1.7.10.4
>>
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Jiri Kosina July 8, 2015, 9:34 a.m. UTC | #3 
On Sat, 20 Jun 2015, Antonio Borneo wrote:

> > Signed-off-by: Ellen Wang <ellen@cumulusnetworks.com>
> > ---
> >  drivers/hid/hid-cp2112.c |   74 ++++++++++++++++++++++++++++++++++------------
> >  1 file changed, 55 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
> > index 5a72819..00d062a 100644
> > --- a/drivers/hid/hid-cp2112.c
> > +++ b/drivers/hid/hid-cp2112.c
> > @@ -153,6 +153,7 @@ MODULE_DEVICE_TABLE(hid, cp2112_devices);
> >  struct cp2112_device {
> >         struct i2c_adapter adap;
> >         struct hid_device *hdev;
> > +       int hwversion;
> 
> No need for int; u8 is enough (value is copyed from buf[2] that is u8).
> Put the new u8 field few lines below, together with the other u8, to
> avoid extra padding.
> 
> No need to send immediately a new version. Let's see if there is any
> other comment and if someone can test it before me.

Antonio, is there any result of your testing? I have put this patch on 
hold waiting for your word on it, but it has been ~3 weeks already.

Thanks,
Ellen Wang July 8, 2015, 10:33 a.m. UTC | #4 
On 07/08/2015 02:34 AM, Jiri Kosina wrote:
> On Sat, 20 Jun 2015, Antonio Borneo wrote:
>
>>> Signed-off-by: Ellen Wang <ellen@cumulusnetworks.com>
>>> ---
>>>   drivers/hid/hid-cp2112.c |   74 ++++++++++++++++++++++++++++++++++------------
>>>   1 file changed, 55 insertions(+), 19 deletions(-)
>>>
>>> diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
>>> index 5a72819..00d062a 100644
>>> --- a/drivers/hid/hid-cp2112.c
>>> +++ b/drivers/hid/hid-cp2112.c
>>> @@ -153,6 +153,7 @@ MODULE_DEVICE_TABLE(hid, cp2112_devices);
>>>   struct cp2112_device {
>>>          struct i2c_adapter adap;
>>>          struct hid_device *hdev;
>>> +       int hwversion;
>>
>> No need for int; u8 is enough (value is copyed from buf[2] that is u8).
>> Put the new u8 field few lines below, together with the other u8, to
>> avoid extra padding.
>>
>> No need to send immediately a new version. Let's see if there is any
>> other comment and if someone can test it before me.
>
> Antonio, is there any result of your testing? I have put this patch on
> hold waiting for your word on it, but it has been ~3 weeks already.
>
> Thanks,

This patch should be applied after my other patch:
https://patchwork.ozlabs.org/patch/492842/
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Jiri Kosina July 9, 2015, 12:22 p.m. UTC | #5 
On Wed, 8 Jul 2015, Ellen Wang wrote:

> > > No need for int; u8 is enough (value is copyed from buf[2] that is u8).
> > > Put the new u8 field few lines below, together with the other u8, to
> > > avoid extra padding.
> > > 
> > > No need to send immediately a new version. Let's see if there is any
> > > other comment and if someone can test it before me.
> > 
> > Antonio, is there any result of your testing? I have put this patch on
> > hold waiting for your word on it, but it has been ~3 weeks already.
> > 
> > Thanks,
> 
> This patch should be applied after my other patch:
> https://patchwork.ozlabs.org/patch/492842/

Well, it actually conflicts with it :) The conflict is easy to resolve, 
but as you might be sending v2 anyway, please rebase it on top of 
for-4.3/cp2112 when doing so.

Thanks,
Ellen Wang July 10, 2015, 7:03 a.m. UTC | #6 
On 07/09/2015 05:22 AM, Jiri Kosina wrote:
> On Wed, 8 Jul 2015, Ellen Wang wrote:
> ...
>> This patch should be applied after my other patch:
>> https://patchwork.ozlabs.org/patch/492842/
>
> Well, it actually conflicts with it :) The conflict is easy to resolve,
> but as you might be sending v2 anyway, please rebase it on top of
> for-4.3/cp2112 when doing so.
>
> Thanks,

v2 sent, based on for-4.3/cp2112.
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diff mbox

Patch

diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index 5a72819..00d062a 100644
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -153,6 +153,7 @@  MODULE_DEVICE_TABLE(hid, cp2112_devices);
 struct cp2112_device {
 	struct i2c_adapter adap;
 	struct hid_device *hdev;
+	int hwversion;
 	wait_queue_head_t wait;
 	u8 read_data[61];
 	u8 read_length;
@@ -444,6 +445,24 @@  static int cp2112_i2c_write_req(void *buf, u8 slave_address, u8 *data,
 	return data_length + 3;
 }
 
+static int cp2112_i2c_write_read_req(void *buf, u8 slave_address,
+				     u8 *addr, int addr_length,
+				     int read_length)
+{
+	struct cp2112_write_read_req_report *report = buf;
+
+	if (read_length < 1 || read_length > 512 ||
+	    addr_length > sizeof(report->target_address))
+		return -EINVAL;
+
+	report->report = CP2112_DATA_WRITE_READ_REQUEST;
+	report->slave_address = slave_address << 1;
+	report->length = cpu_to_be16(read_length);
+	report->target_address_length = addr_length;
+	memcpy(report->target_address, addr, addr_length);
+	return addr_length + 5;
+}
+
 static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			   int num)
 {
@@ -451,26 +470,46 @@  static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	struct hid_device *hdev = dev->hdev;
 	u8 buf[64];
 	ssize_t count;
+	ssize_t read_length = 0;
+	u8 *read_buf = NULL;
 	unsigned int retries;
 	int ret;
 
 	hid_dbg(hdev, "I2C %d messages\n", num);
 
-	if (num != 1) {
+	if (num == 1) {
+		if (msgs->flags & I2C_M_RD) {
+			hid_dbg(hdev, "I2C read %#04x len %d\n",
+				msgs->addr, msgs->len);
+			read_length = msgs->len;
+			read_buf = msgs->buf;
+			count = cp2112_read_req(buf, msgs->addr, msgs->len);
+		} else {
+			hid_dbg(hdev, "I2C write %#04x len %d\n",
+				msgs->addr, msgs->len);
+			count = cp2112_i2c_write_req(buf, msgs->addr,
+						     msgs->buf, msgs->len);
+		}
+		if (count < 0)
+			return count;
+	} else if (dev->hwversion > 1 &&  /* no repeated start in rev 1 */
+		   num == 2 &&
+		   msgs[0].addr == msgs[1].addr &&
+		   !(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD)) {
+		hid_dbg(hdev, "I2C write-read %#04x wlen %d rlen %d\n",
+			msgs[0].addr, msgs[0].len, msgs[1].len);
+		read_length = msgs[1].len;
+		read_buf = msgs[1].buf;
+		count = cp2112_i2c_write_read_req(buf, msgs[0].addr,
+				msgs[0].buf, msgs[0].len, msgs[1].len);
+		if (count < 0)
+			return count;
+	} else {
 		hid_err(hdev,
 			"Multi-message I2C transactions not supported\n");
 		return -EOPNOTSUPP;
 	}
 
-	if (msgs->flags & I2C_M_RD)
-		count = cp2112_read_req(buf, msgs->addr, msgs->len);
-	else
-		count = cp2112_i2c_write_req(buf, msgs->addr, msgs->buf,
-					     msgs->len);
-
-	if (count < 0)
-		return count;
-
 	ret = hid_hw_power(hdev, PM_HINT_FULLON);
 	if (ret < 0) {
 		hid_err(hdev, "power management error: %d\n", ret);
@@ -506,15 +545,12 @@  static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		goto power_normal;
 	}
 
-	if (!(msgs->flags & I2C_M_RD))
-		goto finish;
-
-	for (count = 0; count < msgs->len;) {
-		ret = cp2112_read(dev, msgs->buf + count, msgs->len - count);
+	for (count = 0; count < read_length;) {
+		ret = cp2112_read(dev, read_buf + count, read_length - count);
 		if (ret < 0)
 			goto power_normal;
 		count += ret;
-		if (count > msgs->len) {
+		if (count > read_length) {
 			/*
 			 * The hardware returned too much data.
 			 * This is mostly harmless because cp2112_read()
@@ -524,15 +560,14 @@  static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			 * it shouldn't go unnoticed.
 			 */
 			hid_err(hdev, "long read: %d > %zd\n",
-				ret, msgs->len - count + ret);
+				ret, read_length - count + ret);
 			ret = -EIO;
 			goto power_normal;
 		}
 	}
 
-finish:
 	/* return the number of transferred messages */
-	ret = 1;
+	ret = num;
 
 power_normal:
 	hid_hw_power(hdev, PM_HINT_NORMAL);
@@ -1040,6 +1075,7 @@  static int cp2112_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	dev->adap.dev.parent	= &hdev->dev;
 	snprintf(dev->adap.name, sizeof(dev->adap.name),
 		 "CP2112 SMBus Bridge on hiddev%d", hdev->minor);
+	dev->hwversion = buf[2];
 	init_waitqueue_head(&dev->wait);
 
 	hid_device_io_start(hdev);