Re: [PATCH v2] Input: driver for the Goodix touchpanel

[Bastien Nocera <hadess@hadess.net>]

On Tue, 2014-10-28 at 12:14 -0700, Dmitry Torokhov wrote:
> On Tue, Oct 28, 2014 at 07:59:05PM +0100, Bastien Nocera wrote:
> > On Tue, 2014-10-28 at 11:05 -0700, Dmitry Torokhov wrote:
> > > On Tue, Oct 28, 2014 at 06:55:21PM +0100, Bastien Nocera wrote:
> > > > On Tue, 2014-10-07 at 13:58 -0700, Dmitry Torokhov wrote:
> > > > > On Wed, Sep 24, 2014 at 04:43:58PM +0200, Bastien Nocera wrote:
> > > > > > +static irqreturn_t goodix_ts_irq_handler(int irq, void *dev_id)
> > > > > > +{
> > > > > > +	struct goodix_ts_data *ts = dev_id;
> > > > > > +	u8  end_cmd[1] = {0};
> > > > > > +
> > > > > > +	goodix_process_events(ts);
> > > > > > +
> > > > > > +	if (goodix_i2c_write(ts->client,
> > > > > > +				GOODIX_READ_COOR_ADDR, end_cmd, 1) < 0)
> > > > > > +		dev_err(&ts->client->dev, "I2C write end_cmd error");
> > > > > 
> > > > > I am not happy that we need to allocate/deallocate memory for each
> > > > > interrupt. We only write one command to the driver, we could simply use
> > > > > i2c_master_send() with a constant buffer.
> > > > 
> > > > Sure. But I've split up the patch you sent us, and committed the
> > > > different bits separately in:
> > > > https://github.com/hadess/gt9xx/commits/master
> > > > 
> > > > And this one commit about removing goodix_i2c_write():
> > > > https://github.com/hadess/gt9xx/commit/146b4cc2eed5c67bcf1cb91e845bf9f97da4be1e
> > > > 
> > > > Breaks the driver.
> > > 
> > > Ah, I see. In end_cmd I encoded the address as little endian, whereas it
> > > needs to be beg endian. Just swap "GOODIX_READ_COOR_ADDR & 0xff" and
> > > "GOODIX_READ_COOR_ADDR >> 8" around and I thin kit will work.
> > 
> > Indeed, fixed in:
> > https://github.com/hadess/gt9xx/commit/18e507c5c455a3d3d745380c4d0d561ea470a091
> > 
> > As for the various FIXMEs, could you (that includes Benjamin that
> > probably knows the driver more than he would like to) check whether
> > that's sensible?
> > https://github.com/hadess/gt9xx/commit/35b94f327edc04d95a7208a667553566faa871e3
> > 
> > If it is, I'll respin the patch and send it for merging.
> 
> No, the "header" is not 10 bytes as far as I can see. IIUIC the device
> sends packet with 1st byte containing number of contacts + (n_contacts *
> GOODIX_CONTACT_SIZE) worth of data. The driver tries to optimize for
> single-touch scenario and reads the counter and the very first contact
> data and if the counter indicates more than one contact it will issue
> second i2c transaction to read in the rest.
> 
> Your change did not alter the actual code, it just converted constant 10
> into a define.

Not quite, but that's besides the point.

> Please try changing FIXMEs exactly as they were and see if the driver
> still works properly.

I did, and it still works properly. I also don't understand how it could
have worked properly before...

Should I still add those linefeeds to all the print statements in the
driver?

Cheers