Re: [PATCH] HID:i2c-hid: add a simple quirk to fix device defects

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

On Nov 08 2016 or thereabouts, hn.chen@weidahitech.com wrote:
> From: HungNien Chen <hn.chen@weidahitech.com>
> 
> Weida's device can get a quirk value by the quirk function.
> Base on the quirk value, set_power function will send a command
> to wake up the device before send the PWR_ON command.
> 
> Signed-off-by: HungNien Chen <hn.chen@weidahitech.com>
> ---
>  drivers/hid/hid-ids.h         |  5 +++++
>  drivers/hid/i2c-hid/i2c-hid.c | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> index 6cfb5ca..787afdf 100644
> --- a/drivers/hid/hid-ids.h
> +++ b/drivers/hid/hid-ids.h
> @@ -1033,6 +1033,11 @@
>  #define USB_DEVICE_ID_WALTOP_MEDIA_TABLET_14_1_INCH	0x0500
>  #define USB_DEVICE_ID_WALTOP_SIRIUS_BATTERY_FREE_TABLET	0x0502
>  
> +#define	USB_VENDOR_ID_WEIDA		0x2575
> +#define	USB_DEVICE_ID_WEIDA_8756	0x8756
> +#define	USB_DEVICE_ID_WEIDA_8752	0xC300
> +#define	USB_DEVICE_ID_WEIDA_8755	0xC301
> +
>  #define USB_VENDOR_ID_WISEGROUP		0x0925
>  #define USB_DEVICE_ID_SMARTJOY_PLUS	0x0005
>  #define USB_DEVICE_ID_SUPER_JOY_BOX_3	0x8888
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index b3ec4f2..7a9b100 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -41,6 +41,11 @@
>  
>  #include <linux/i2c/i2c-hid.h>
>  
> +#include "../hid-ids.h"
> +
> +/* quirks to control the device */
> +#define I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV	(1 << 0)
> +
>  /* flags */
>  #define I2C_HID_STARTED		0
>  #define I2C_HID_RESET_PENDING	1
> @@ -143,6 +148,7 @@ struct i2c_hid {
>  	char			*argsbuf;	/* Command arguments buffer */
>  
>  	unsigned long		flags;		/* device flags */
> +	unsigned long		quirks;		/* Various quirks */
>  
>  	wait_queue_head_t	wait;		/* For waiting the interrupt */
>  	struct gpio_desc	*desc;
> @@ -154,6 +160,25 @@ struct i2c_hid {
>  	struct mutex		reset_lock;
>  };
>  
> +/*
> + * i2c_hid_lookup_quirk: return any quirks associated with a I2C HID device
> + * @idVendor: the 16-bit vendor ID
> + * @idProduct: the 16-bit product ID
> + *
> + * Returns: a u32 quirks value.
> + */
> +static u32 i2c_hid_lookup_quirk(const u16 idVendor, const u16 idProduct)
> +{
> +	u32 quirks = 0;
> +
> +	/* Weida devices check here */
> +	if (idVendor == USB_VENDOR_ID_WEIDA &&
> +	    idProduct >= USB_DEVICE_ID_WEIDA_8752)

Wouldn't it make more sense to have a static table of the affected
products, instead of this test?

> +		return I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV;
> +
> +	return quirks;
> +}
> +
>  static int __i2c_hid_command(struct i2c_client *client,
>  		const struct i2c_hid_cmd *command, u8 reportID,
>  		u8 reportType, u8 *args, int args_len,
> @@ -346,6 +371,11 @@ static int i2c_hid_set_power(struct i2c_client *client, int power_state)
>  
>  	i2c_hid_dbg(ihid, "%s\n", __func__);
>  
> +	/* Some devices require to send a command to wakeup first */
> +	if (power_state == I2C_HID_PWR_ON &&
> +	    ihid->quirks & I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV)
> +		i2c_hid_command(client, &hid_set_power_cmd, NULL, 0);

Isn't there a need to check the return value here?

> +
>  	ret = __i2c_hid_command(client, &hid_set_power_cmd, power_state,
>  		0, NULL, 0, NULL, 0);
>  	if (ret)
> @@ -661,6 +691,8 @@ static int i2c_hid_parse(struct hid_device *hid)
>  
>  	i2c_hid_dbg(ihid, "entering %s\n", __func__);
>  
> +	ihid->quirks = i2c_hid_lookup_quirk(hid->vendor, hid->product);

Please lookup for the quirks in i2c_hid_probe(), right after we set
version, vendor and product

> +
>  	rsize = le16_to_cpu(hdesc->wReportDescLength);
>  	if (!rsize || rsize > HID_MAX_DESCRIPTOR_SIZE) {
>  		dbg_hid("weird size of report descriptor (%u)\n", rsize);
> -- 
> 1.9.1
> 

Cheers,
Benjamin