[lkml]   [2018]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v6 0/2] Input: Add Cypress Gen5 Touchscreen driver
Hello Dmitry,

On Wed, 4 Jul 2018 16:21:58 +0000
Dmitry Torokhov <> wrote:

> Hi Mylène,
> On Tue, Jul 03, 2018 at 11:43:07AM +0200, Mylène Josserand wrote:
> > Hello,
> >
> > Here is a V6 series to add the driver of the touchscreen Cypress,
> > TrueTouch Generation 5.
> > Based on v4.18-rc3.
> >
> > This patch series has already been posted in several iterations:
> > - v1: Sent on 2017/05/29
> > - v2: Sent on 2017/08/18
> > - v3: Sent on 2017/09/27
> > - v4: Sent on 2017/12/01
> > - v5: Sent on 2017/12/20
> >
> > I did not have any comments the last 4 versions.
> > And no reviews on my v5 during 6 months. Could I have any updates
> > or feedback on my series to know why it is not merged (to be able to
> > correct what is wrong)?
> Sorry, I must have missed the v5, sorry about that.
> I probably asked this question before, but just to make sure - I see
> references to HID in the patch - the device is really not HID
> compatible? Is there any hope it could be made work with i2c-hid +
> hid-multitouch?
> Thanks.

I have checked and, for what I have seen, all the HID descriptor stuff
is HID compliant. We could definitely use i2c-hid and hid-multitouch
(there is the "hid-cypress" driver that exists also).

The only problem is that this touchscreen has two modes: a bootloader
mode and an application mode (which is the one where we can send
HID commands). After a power-on-reset, it is always in "bootloader"
mode so we need to send some commands (called "bootloader commands") to
switch to application mode. These commands are not HID-compliant as the
datasheet indicates:

"Bootloader commands are not HID-over-I2C compliant."

I think that if the touchscreen would start directly in "application"
mode, we could directly use i2c-hid and hid-cypress drivers.
Unfortunately, this is not the case.

In bootloader mode, the ProductID is 0xc101 and in application mode, it
is 0xc001 (already available in hid-ids.h:

What would be the better approach here?
Should I add a new product ID to detect the bootloader mode in
hid-cypress driver and send non-HID commands to switch to
"application" mode in this driver?
Anyway, I guess that I will drop this cyttsp5 driver and update the
existing one, right?

Let me know what you think about it.

Thank you in advance,

Best regards,

Mylène Josserand, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering

 \ /
  Last update: 2018-07-24 15:01    [W:0.130 / U:6.352 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site