On Fri, Feb 26, 2016 at 06:50:21PM +0000, Alan wrote:
> From: Lingfeng Yang <lfy@xxxxxxxxxx>
>
> If we send SYN_REPORT on every single multi-touch event, it breaks the
> multi-touch.
>
> The multi-touch becomes jerky and you have to click 2-3 times to do things
> while randomly activating notification bars when not clicking.
>
> If we suppress these SYN_REPORTS, multi-touch will work fine and the events
> will have a protocol that looks nice.
>
> We need to register Goldfish Events as a multi-touch device by issuing
> input_mt_init_slots, otherwise input_handle_abs_event in drivers/input/input.c
> will silently drop all ABS_MT_SLOT events, causing touches of more than one
> finger to fail.
>
> Signed-off-by: Lingfeng Yang <lfy@xxxxxxxxxx>
> Signed-off-by: Jin Qian <jinqian@xxxxxxxxxxx>
> Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
> ---
> drivers/input/keyboard/goldfish_events.c | 30 +++++++++++++++++++++++++++++-
> 1 file changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/keyboard/goldfish_events.c b/drivers/input/keyboard/goldfish_events.c
> index c7e308a..c0d77b7 100644
> --- a/drivers/input/keyboard/goldfish_events.c
> +++ b/drivers/input/keyboard/goldfish_events.c
> @@ -17,6 +17,7 @@
> #include <linux/interrupt.h>
> #include <linux/types.h>
> #include <linux/input.h>
> +#include <linux/input/mt.h>
> #include <linux/kernel.h>
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> @@ -24,6 +25,8 @@
> #include <linux/io.h>
> #include <linux/acpi.h>
>
> +#define GOLDFISH_MAX_FINGERS 5
> +
> enum {
> REG_READ = 0x00,
> REG_SET_PAGE = 0x00,
> @@ -52,7 +55,23 @@ static irqreturn_t events_interrupt(int irq, void *dev_id)
> value = __raw_readl(edev->addr + REG_READ);
>
> input_event(edev->input, type, code, value);
> - input_sync(edev->input);
> + /*
> + * Send an extra (EV_SYN, SYN_REPORT, 0x0) event
> + * if a key was pressed. Some keyboard device
> + * drivers may only send the EV_KEY event and
> + * not EV_SYN.
That would be error in that keyboard driver and should be fixed.
> + * Note that sending an extra SYN_REPORT is not
> + * necessary nor correct protocol with other
> + * devices such as touchscreens, which will send
> + * their own SYN_REPORT's when sufficient event
> + * information has been collected (e.g., for
> + * touchscreens, when pressure and X/Y coordinates
> + * have been received). Hence, we will only send
> + * this extra SYN_REPORT if type == EV_KEY.
> + */
> + if (type == EV_KEY)
> + input_sync(edev->input);
I'd rather we always rely on the host to send the SYN event.
> +
> return IRQ_HANDLED;
> }
>
> @@ -154,6 +173,15 @@ static int events_probe(struct platform_device *pdev)
>
> input_dev->name = edev->name;
> input_dev->id.bustype = BUS_HOST;
> + /*
> + * Set the Goldfish Device to be multi-touch.
> + * If we do not issue input_mt_init_slots,
> + * the kernel will filter out needed ABS_MT_SLOT
> + * events when we touch the screen in more than one place,
> + * preventing multi-touch with more than one finger from working.
> + * See drivers/input/input.c:input_handle_abs_event.
> + */
> + input_mt_init_slots(input_dev, GOLDFISH_MAX_FINGERS, 0);
Can we use data retrieved by events_import_abs_params() to set up
correct number of slots? Also we need error handling. And possibly
retrieve correct properties to set pass to input_mt_init_slots()...
>
> events_import_bits(edev, input_dev->evbit, EV_SYN, EV_MAX);
> events_import_bits(edev, input_dev->keybit, EV_KEY, KEY_MAX);
>
Thanks.
--
Dmitry
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