linux-kernel - Re: [PATCH RESEND v2] virtio-input: add multi-touch support

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Date:   Tue, 8 Dec 2020 14:05:05 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Vasyl Vavrychuk <vasyl.vavrychuk@...nsynergy.com>
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        stable@...r.kernel.org, "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Henrik Rydberg <rydberg@...math.org>,
        Mathias Crombez <mathias.crombez@...recia.com>
Subject: Re: [PATCH RESEND v2] virtio-input: add multi-touch support

Hi Vasyl,

On Tue, Dec 08, 2020 at 11:01:50PM +0200, Vasyl Vavrychuk wrote:
> From: Mathias Crombez <mathias.crombez@...recia.com>
> 
> Without multi-touch slots allocated, ABS_MT_SLOT events will be lost by
> input_handle_abs_event.
> 
> Signed-off-by: Mathias Crombez <mathias.crombez@...recia.com>
> Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@...nsynergy.com>
> Tested-by: Vasyl Vavrychuk <vasyl.vavrychuk@...nsynergy.com>
> ---
> v2: fix patch corrupted by corporate email server
> 
>  drivers/virtio/Kconfig        | 11 +++++++++++
>  drivers/virtio/virtio_input.c |  8 ++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index 7b41130d3f35..2cfd5b01d96d 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -111,6 +111,17 @@ config VIRTIO_INPUT
>  
>  	 If unsure, say M.
>  
> +config VIRTIO_INPUT_MULTITOUCH_SLOTS
> +	depends on VIRTIO_INPUT
> +	int "Number of multitouch slots"
> +	range 0 64
> +	default 10
> +	help
> +	 Define the number of multitouch slots used. Default to 10.
> +	 This parameter is unused if there is no multitouch capability.

I believe the number of slots should be communicated to the guest by
the host, similarly to how the rest of input device capabilities is
transferred, instead of having static compile-time option.

> +
> +	 0 will disable the feature.
> +
>  config VIRTIO_MMIO
>  	tristate "Platform bus driver for memory mapped virtio devices"
>  	depends on HAS_IOMEM && HAS_DMA
> diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
> index f1f6208edcf5..13f3d90e6c30 100644
> --- a/drivers/virtio/virtio_input.c
> +++ b/drivers/virtio/virtio_input.c
> @@ -7,6 +7,7 @@
>  
>  #include <uapi/linux/virtio_ids.h>
>  #include <uapi/linux/virtio_input.h>
> +#include <linux/input/mt.h>
>  
>  struct virtio_input {
>  	struct virtio_device       *vdev;
> @@ -205,6 +206,7 @@ static int virtinput_probe(struct virtio_device *vdev)
>  	unsigned long flags;
>  	size_t size;
>  	int abs, err;
> +	bool is_mt = false;
>  
>  	if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
>  		return -ENODEV;
> @@ -287,9 +289,15 @@ static int virtinput_probe(struct virtio_device *vdev)
>  		for (abs = 0; abs < ABS_CNT; abs++) {
>  			if (!test_bit(abs, vi->idev->absbit))
>  				continue;
> +			if (input_is_mt_value(abs))
> +				is_mt = true;
>  			virtinput_cfg_abs(vi, abs);
>  		}
>  	}
> +	if (is_mt)
> +		input_mt_init_slots(vi->idev,
> +				    CONFIG_VIRTIO_INPUT_MULTITOUCH_SLOTS,
> +				    INPUT_MT_DIRECT);

Here errors need to be handled.

>  
>  	virtio_device_ready(vdev);
>  	vi->ready = true;
> -- 
> 2.23.0
> 

Thanks.

-- 
Dmitry