linux-kernel - Re: [PATCH 2/2] Input: ili210x

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Date:   Tue, 5 Nov 2019 10:29:53 -0500
From:   Sven Van Asbroeck <thesven73@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Adam Ford <aford173@...il.com>, Marek Vasut <marex@...x.de>,
        linux-input@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] Input: ili210x - add ILI2117 support

On Mon, Nov 4, 2019 at 6:36 PM Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
>
> OK, I refreshed the branch with fixes and a couple of new patches. It is
> on top of 5.3 now. If this works for you guys I will be merging it for
> 5.5.
>

According to the ili2117a/2118a datasheet I have, there are still a
few loose ends.
Some of these might be too inconsequential to worry about.
Dmitry, tell me which ones you think are important, if any,
and I will spin a patch if you like. Or you can do it, just let me know.

>       { "ili210x", (long)&ili210x_chip },
>       { "ili2117", (long)&ili211x_chip },
>       { "ili251x", (long)&ili251x_chip },
>
>       { .compatible = "ilitek,ili210x", .data = &ili210x_chip },
>       { .compatible = "ilitek,ili2117", .data = &ili211x_chip },
>       { .compatible = "ilitek,ili251x", .data = &ili251x_chip },

My datasheet says ILI2117A/ILI2118A, so maybe the compatible string should
really be "ilitek,ili211x", just like the other variants ?

In addition, should we add ili2117/ili2118 in comments somewhere, so others
can find this driver with a simple grep?

>       error = devm_device_add_group(dev, &ili210x_attr_group);
>       if (error) {
>               dev_err(dev, "Unable to create sysfs attributes, err: %d\n",
>                       error);
>               return error;
>       }

The ili2117/ili2118 does not have a calibrate register, so this sysfs group
is unsupported and perhaps may even be harmful if touched (?).

Perhaps add a flag to struct ili2xxx_chip ?

>       input_set_abs_params(input, ABS_MT_POSITION_X, 0, 0xffff, 0, 0);
>       input_set_abs_params(input, ABS_MT_POSITION_Y, 0, 0xffff, 0, 0);

The max position on ili2117/8 is 0xfff. The OS I'm using (Android) likes to know
the correct min and max. So it can map touch coords to pixel coords.

Perhaps add this to struct ili2xxx_chip ?

>       /* Get firmware version */
>       error = chip->read_reg(client, REG_FIRMWARE_VERSION,
>                              &firmware, sizeof(firmware));

On ili2117/ili2118, the firmware version register is different (0x03), and
the layout is different too:

byte    name
0       vendor id
1       reserved
2       firmware version upper
3       firmware version lower
4       reserved
5       reserved
6       reserved
7       reserved

But, does it even make sense to retrieve the firmware version? All it's used
for is a dev_dbg log print, which under normal circumstances is a noop:

>       dev_dbg(dev,
>               "ILI210x initialized (IRQ: %d), firmware version %d.%d.%d",
>               client->irq, firmware.id, firmware.major, firmware.minor);