Re: [PATCH v2] HID: i2c-hid: support sending HID output reports usingthe output register

From: Benjamin Tissoires
Date: Tue Jun 18 2013 - 04:27:21 EST


On 06/18/2013 01:15 AM, Andrew Duggan wrote:
> The current i2c hid driver does not support sending HID output reports using
> the output register for devices which support receiving reports through this
> method. This patch determines which method to use to send output reports based
> on the value of wMaxOutputLength in the device's HID descriptor.
>
> Signed-off-by: Andrew Duggan <aduggan@xxxxxxxxxxxxx>

Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>

Cheers,
Benjamin

> ---
> This is the second version of the patch which includes Benjamin's suggestions. The comment
> now follows the multi line guidelines and in the i2c_hid_set_report function, hidcmd is now
> a pointer.
> drivers/hid/i2c-hid/i2c-hid.c | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index 2b1799a..879b0ed 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -108,6 +108,7 @@ static const struct i2c_hid_cmd hid_reset_cmd = { I2C_HID_CMD(0x01),
> static const struct i2c_hid_cmd hid_get_report_cmd = { I2C_HID_CMD(0x02) };
> static const struct i2c_hid_cmd hid_set_report_cmd = { I2C_HID_CMD(0x03) };
> static const struct i2c_hid_cmd hid_set_power_cmd = { I2C_HID_CMD(0x08) };
> +static const struct i2c_hid_cmd hid_no_cmd = { .length = 0 };
>
> /*
> * These definitions are not used here, but are defined by the spec.
> @@ -259,8 +260,11 @@ static int i2c_hid_set_report(struct i2c_client *client, u8 reportType,
> {
> struct i2c_hid *ihid = i2c_get_clientdata(client);
> u8 *args = ihid->argsbuf;
> + const struct i2c_hid_cmd * hidcmd = &hid_set_report_cmd;
> int ret;
> u16 dataRegister = le16_to_cpu(ihid->hdesc.wDataRegister);
> + u16 outputRegister = le16_to_cpu(ihid->hdesc.wOutputRegister);
> + u16 maxOutputLength = le16_to_cpu(ihid->hdesc.wMaxOutputLength);
>
> /* hidraw already checked that data_len < HID_MAX_BUFFER_SIZE */
> u16 size = 2 /* size */ +
> @@ -278,8 +282,18 @@ static int i2c_hid_set_report(struct i2c_client *client, u8 reportType,
> reportID = 0x0F;
> }
>
> - args[index++] = dataRegister & 0xFF;
> - args[index++] = dataRegister >> 8;
> + /*
> + * use the data register for feature reports or if the device does not
> + * support the output register
> + */
> + if (reportType == 0x03 || maxOutputLength == 0) {
> + args[index++] = dataRegister & 0xFF;
> + args[index++] = dataRegister >> 8;
> + } else {
> + args[index++] = outputRegister & 0xFF;
> + args[index++] = outputRegister >> 8;
> + hidcmd = &hid_no_cmd;
> + }
>
> args[index++] = size & 0xFF;
> args[index++] = size >> 8;
> @@ -289,7 +303,7 @@ static int i2c_hid_set_report(struct i2c_client *client, u8 reportType,
>
> memcpy(&args[index], buf, data_len);
>
> - ret = __i2c_hid_command(client, &hid_set_report_cmd, reportID,
> + ret = __i2c_hid_command(client, hidcmd, reportID,
> reportType, args, args_len, NULL, 0);
> if (ret) {
> dev_err(&client->dev, "failed to set a report to device.\n");
>

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