linux-kernel - Re: [PATCH RESEND v8 4/4] input: elants: support 0x66 reply opcode for reporting touches

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Message-ID: <X9MhlP8+e6WXukv8@google.com>
Date:   Thu, 10 Dec 2020 23:36:52 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Michał Mirosław <mirq-linux@...e.qmqm.pl>
Cc:     Dmitry Osipenko <digetx@...il.com>,
        Johnny Chuang <johnny.chuang.emc@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v8 4/4] input: elants: support 0x66 reply opcode
 for reporting touches

On Fri, Dec 11, 2020 at 07:53:57AM +0100, Michał Mirosław wrote:
> From: Dmitry Osipenko <digetx@...il.com>
> 
> eKTF3624 touchscreen firmware uses two variants of the reply opcodes for
> reporting touch events: one is 0x63 (used by older firmware) and other is
> 0x66 (used by newer firmware). The 0x66 variant is equal to 0x63 of
> eKTH3500, while 0x63 needs small adjustment of the touch pressure value.
> 
> Nexus 7 tablet device has eKTF3624 touchscreen and it uses 0x66 opcode for
> reporting touch events, let's support it now. Other devices, eg. ASUS TF300T,
> use 0x63.
> 
> Note: CMD_HEADER_REK is used for replying to calibration requests, it has
> the same 0x66 opcode number which eKTF3624 uses for reporting touches.
> The calibration replies are handled separately from the the rest of the
> commands in the driver by entering into ELAN_WAIT_RECALIBRATION state
> and thus this change shouldn't change the old behavior.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> Tested-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> ---
>  drivers/input/touchscreen/elants_i2c.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
> index c24d8cdc4251..1cbda6f20d07 100644
> --- a/drivers/input/touchscreen/elants_i2c.c
> +++ b/drivers/input/touchscreen/elants_i2c.c
> @@ -61,6 +61,15 @@
>  #define QUEUE_HEADER_NORMAL	0X63
>  #define QUEUE_HEADER_WAIT	0x64
>  
> +/*
> + * Depending on firmware version, eKTF3624 touchscreens may utilize one of
> + * these opcodes for the touch events: 0x63 and 0x66. The 0x63 is used by
> + * older firmware version and differs from 0x66 such that touch pressure
> + * value needs to be adjusted. The 0x66 opcode of newer firmware is equal
> + * to 0x63 of eKTH3500.
> + */
> +#define QUEUE_HEADER_NORMAL2	0x66
> +
>  /* Command header definition */
>  #define CMD_HEADER_WRITE	0x54
>  #define CMD_HEADER_READ		0x53
> @@ -1052,7 +1061,6 @@ static irqreturn_t elants_i2c_irq(int irq, void *_dev)
>  		switch (ts->buf[FW_HDR_TYPE]) {
>  		case CMD_HEADER_HELLO:
>  		case CMD_HEADER_RESP:
> -		case CMD_HEADER_REK:
>  			break;
>  
>  		case QUEUE_HEADER_WAIT:
> @@ -1072,6 +1080,7 @@ static irqreturn_t elants_i2c_irq(int irq, void *_dev)
>  			break;
>  
>  		case QUEUE_HEADER_NORMAL:
> +		case QUEUE_HEADER_NORMAL2:

I think here I would also prefer that we only accepted this for the
devices where we expect to see such packets:

		case CMD_HEADER_REK:
			/* comment from above why this is done ... */
			if (ts->chip_id != EKTF3624)
				break;
			fallthrough;
		case QUEUE_HEADER_NORMAL2:

...

Given this comments I wonder if it would not make sense to combine the 3
patches into one adding support for EKTF3624...


>  			report_count = ts->buf[FW_HDR_COUNT];
>  			if (report_count == 0 || report_count > 3) {
>  				dev_err(&client->dev,
> -- 
> 2.20.1
> 

Thanks.

-- 
Dmitry