linux-kernel - Re: [PATCH 2/4] Input: goodix - Allow tweaking of configuration file dynamically

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Date:   Thu, 27 Oct 2016 19:41:23 +0200
From:   Bastien Nocera <hadess@...ess.net>
To:     Franklin S Cooper Jr <fcooper@...com>, dmitry.torokhov@...il.com,
        robh+dt@...nel.org, octavian.purdila@...el.com,
        irina.tirdea@...el.com, merker@...ian.org,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, nsekhar@...com, nm@...com
Subject: Re: [PATCH 2/4] Input: goodix - Allow tweaking of configuration
 file dynamically

On Thu, 2016-10-27 at 11:58 -0500, Franklin S Cooper Jr wrote:
> 
> On 10/27/2016 05:33 AM, Bastien Nocera wrote:
> > On Thu, 2016-10-20 at 14:59 -0500, Franklin S Cooper Jr wrote:
> > > Some goodix touchscreen controllers don't have the correct
> > > configuration
> > > firmware for the display panel it is attached to. Therefore,
> > > settings
> > > such
> > > as touchscreen x and y size may need to be passed in via DT and
> > > have
> > > the
> > > panel reprogrammed for the updated touchscreen resolution.
> > > 
> > > This patchset adds support for reading the current configuration
> > > firmware
> > > on the panel and allowing it to be modified and rewritten back to
> > > the
> > > device.
> > > 
> > > Currently this function is unused but later patches will make use
> > > of
> > > it.
> > > 
> > > Signed-off-by: Franklin S Cooper Jr <fcooper@...com>
> > > ---
> > >  drivers/input/touchscreen/goodix.c | 28
> > > ++++++++++++++++++++++++++++
> > >  1 file changed, 28 insertions(+)
> > > 
> > > diff --git a/drivers/input/touchscreen/goodix.c
> > > b/drivers/input/touchscreen/goodix.c
> > > index a43c8ca..01e12f8 100644
> > > --- a/drivers/input/touchscreen/goodix.c
> > > +++ b/drivers/input/touchscreen/goodix.c
> > > @@ -478,6 +478,34 @@ static int goodix_get_gpio_config(struct
> > > goodix_ts_data *ts)
> > >  	return 0;
> > >  }
> > >  
> > > +static void goodix_tweak_config(struct goodix_ts_data *ts)
> > > +{
> > > +	u8 config[GOODIX_CONFIG_MAX_LENGTH];
> > > +	int error;
> > > +	int raw_cfg_len;
> > > +	u8 check_sum = 0;
> > > +
> > > +	raw_cfg_len = ts->cfg_len - 2;
> > > +
> > > +	error = goodix_i2c_read(ts->client,
> > > GOODIX_REG_CONFIG_DATA,
> > > +				config, ts->cfg_len);
> > > +	if (error) {
> > > +		dev_warn(&ts->client->dev,
> > > +			 "Error reading config (%d), avoid
> > > tweaking
> > > config\n",
> > > +			 error);
> > > +		return;
> > > +	}
> > 
> > Please add a placeholder comment here, to go along with the commit
> > message explanation.
> 
> You just want a comment here stating that changes to the firmware
> should
> be made here?

Yes, at least for this intermediary patch. You can remove in in
subsequent patches when it's clearer that this is where things go.

> > > +	check_sum = goodix_calculate_checksum(ts->cfg_len,
> > > config);
> > > +
> > > +	config[raw_cfg_len] = check_sum;
> > > +	config[raw_cfg_len + 1] = 1;
> > > +
> > > +	error = goodix_send_cfg(ts, ts->cfg_len, config);
> > > +	if (error)
> > > +		dev_warn(&ts->client->dev,
> > > +			 "Error writing config (%d)\n", error);
> > > +}
> > >  /**
> > >   * goodix_read_config - Read the embedded configuration of the
> > > panel
> > >   *