Re: [PATCH 3/3] goldfish: multitouch: no extra EV_SYN
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: 2016-02-26 19:57:50
On Fri, Feb 26, 2016 at 06:50:21PM +0000, Alan wrote:
quoted hunk ↗ jump to hunk
From: Lingfeng Yang <redacted> 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 <redacted> Signed-off-by: Jin Qian <redacted> Signed-off-by: Alan Cox <redacted> --- 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.
quoted hunk ↗ jump to hunk
+ 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