linux-kernel - Re: [PATCH] Fix for Acer Bluetooth Optical Rechargeable Mouse

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Message-Id: <20090723132810.6a7aa3dc.akpm@linux-foundation.org>
Date:	Thu, 23 Jul 2009 13:28:10 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Lamarque Vieira Souza <lamarque@...il.com>
Cc:	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Fix for Acer  Bluetooth Optical Rechargeable Mouse

On Fri, 17 Jul 2009 03:01:43 -0300
Lamarque Vieira Souza <lamarque@...il.com> wrote:

> 	This patch works around one problem with my Acer Bluetooth Optical 
> Rechargeable Mouse where the cursor gets stuck at screen's upper-left corner. 
> Even my notebook's touchpad is not able to move cursor when the bluetooth 
> mouse is connected to my Acer Ferrari 4005 notebook. Using input session 
> instead of hid session solves this problem although the cursor still moves a 
> little sluggishly with the bluetooth mouse, cursor moves correctly using the 
> touchpad. My bluetooth mouse used to work well (no sluggish) until kernel 
> 2.6.21, since then the problems are getting worse with each kernel release (it 
> got sluggish in 2.6.22 and this this upper-left corner problem appeared in 
> 2.6.28 or 2.6.27).

The patch also adds a new general quirk infrastructure to the hidp
core.  That's worth noting in the changelog!  I added this:

   The patch adds a general quirk handling framework to the HIDP
   core and then uses this framework to implement a quirk for this
   device.


> linux-2.6.30.1-lvs/net/bluetooth/hidp/core.c
> --- linux-2.6.30.1-orig/net/bluetooth/hidp/core.c	2009-07-16 
> 23:53:04.697925121 -0300
> +++ linux-2.6.30.1-lvs/net/bluetooth/hidp/core.c	2009-07-17 02:35:03.969927384 
> -0300
> @@ -73,6 +73,43 @@ static unsigned char hidp_keycode[256] =
>  
>  static unsigned char hidp_mkeyspat[] = { 0x01, 0x01, 0x01, 0x01, 0x01, 0x01 
> };
>  
> +/* HIDP device quirks */
> +enum {
> +	HIDP_QUIRK_USE_INPUT_SESSION
> +};
> +
> +struct quirk_id {
> +	__u16 vendor;
> +	__u16 product;
> +	unsigned long quirks;
> +};
> +
> +static const struct quirk_id hidp_quirks[] = {
> +	{
> +		/* Lamarque: Acer Bluetooth Optical Rechargeable Mouse
> +		 * does not work properly with hid session since 2.6.27. */
> +		.vendor = 0x0458,
> +		.product = 0x0058,
> +		.quirks = 1 << HIDP_QUIRK_USE_INPUT_SESSION
> +	},
> +
> +	{ /* end: all zeroes */ }
> +};
> +
> +static int quirk_test_bit(__u16 vendor, __u16 product, int quirk)
> +{
> +	const struct quirk_id *q = &hidp_quirks[0];
> +
> +	while (q->vendor != vendor && q->product != product &&
> +	       q->vendor && q->product)
> +		q++;
> +
> +	if (q->vendor == vendor && q->product == product)
> +		return test_bit(quirk, &q->quirks);
> +
> +	return 0;
> +}

Looks OK, but...

It's a bit neater (IMO) and probably more efficient to replace the
null-terminated search with a fixed-size one, using ARRAY_SIZE().

How does this look?

static const struct quirk_id hidp_quirks[] = {
	{
		/* Lamarque: Acer Bluetooth Optical Rechargeable Mouse
		 * does not work properly with hid session since 2.6.27. */
		.vendor = 0x0458,
		.product = 0x0058,
		.quirks = 1 << HIDP_QUIRK_USE_INPUT_SESSION
	},
};

static int quirk_test_bit(__u16 vendor, __u16 product, int quirk)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(hidp_quirks); i++) {
		const struct quirk_id *q = hidp_quirks + i;
	
		if (q->vendor == vendor && q->product == product)
			return test_bit(quirk, &q->quirks);
	}

	return 0;
}



Incremental patch:

--- a/net/bluetooth/hidp/core.c~bluetooth-fix-for-acer-bluetooth-optical-rechargeable-mouse-fix
+++ a/net/bluetooth/hidp/core.c
@@ -92,20 +92,18 @@ static const struct quirk_id hidp_quirks
 		.product = 0x0058,
 		.quirks = 1 << HIDP_QUIRK_USE_INPUT_SESSION
 	},
-
-	{ /* end: all zeroes */ }
 };
 
 static int quirk_test_bit(__u16 vendor, __u16 product, int quirk)
 {
-	const struct quirk_id *q = &hidp_quirks[0];
+	int i;
 
-	while (q->vendor != vendor && q->product != product &&
-	       q->vendor && q->product)
-		q++;
+	for (i = 0; i < ARRAY_SIZE(hidp_quirks); i++) {
+		const struct quirk_id *q = hidp_quirks + i;
 
-	if (q->vendor == vendor && q->product == product)
-		return test_bit(quirk, &q->quirks);
+		if (q->vendor == vendor && q->product == product)
+			return test_bit(quirk, &q->quirks);
+	}
 
 	return 0;
 }
_

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