Message-ID: <20260126100554.GC593812@killaraus>
Date: Mon, 26 Jan 2026 12:05:54 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Svyatoslav Ryhel <clamor95@...il.com>
Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-media@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] media: i2c: mt9m114: add support for Aptina MI1040

On Mon, Jan 26, 2026 at 11:50:05AM +0200, Svyatoslav Ryhel wrote:
> пн, 26 січ. 2026 р. о 11:35 Sakari Ailus <sakari.ailus@...ux.intel.com> пише:
> > On Mon, Jan 26, 2026 at 10:34:30AM +0200, Svyatoslav Ryhel wrote:
> > > Slightly different version of MT9M114 camera module is used in a several
> > > devices like ASUS Nexus 7 (2012) or ASUS Transformer Prime TF201 and is
> > > called Aptina MI1040. Only difference found so far is lacking ability to
> >
> > s/Only/The only/
> >
> > > poll STATUS and COMMAND registers during power on sequence, which causes
> > > driver to fail with time out error. Add polling flag to diverge models and
> > > address quirk found in MI1040.
> > >
> > > Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> > > ---
> > >  drivers/media/i2c/mt9m114.c | 35 ++++++++++++++++++++++++++++-------
> > >  1 file changed, 28 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/media/i2c/mt9m114.c b/drivers/media/i2c/mt9m114.c
> > > index 4ec033c0ee84..d96a57ebcad4 100644
> > > --- a/drivers/media/i2c/mt9m114.c
> > > +++ b/drivers/media/i2c/mt9m114.c
> > > @@ -368,6 +368,10 @@ enum {
> > >   * Data Structures
> > >   */
> > >
> > > +struct mt9m114_model_info {
> > > +     bool polling;
> > > +};
> > > +
> > >  enum mt9m114_format_flag {
> > >       MT9M114_FMT_FLAG_PARALLEL = BIT(0),
> > >       MT9M114_FMT_FLAG_CSI2 = BIT(1),
> > > @@ -421,6 +425,8 @@ struct mt9m114 {
> > >
> > >               struct v4l2_ctrl *tpg[4];
> > >       } ifp;
> > > +
> > > +     const struct mt9m114_model_info *info;
> > >  };
> > >
> > >  /* -----------------------------------------------------------------------------
> > > @@ -2186,9 +2192,11 @@ static int mt9m114_power_on(struct mt9m114 *sensor)
> > >        */
> > >       usleep_range(44500, 50000);
> > >
> > > -     ret = mt9m114_poll_command(sensor, MT9M114_COMMAND_REGISTER_SET_STATE);
> > > -     if (ret < 0)
> > > -             goto error_clock;
> > > +     if (sensor->info->polling) {
> > > +             ret = mt9m114_poll_command(sensor, MT9M114_COMMAND_REGISTER_SET_STATE);
> > > +             if (ret < 0)
> > > +                     goto error_clock;
> > > +     }
> >
> > What does the datasheet say, is there a need to do something else instead?
> > As the polling is there to ensure firmware has done its job, the need
> > appears to still be there.
> 
> MI1040 has no datasheet available and downstream code does not do this
> polling. I have tested on Nexus 7 which has this camera and it seems
> to be fully operational without this poling, but as soon it is enabled
> camera fails will timeout. I suspect that this camera version has some
> quirk regarding early access, but I cannot back it up by any
> documentation or additional data.
> 
> I have a device with proper version of mt9m114 too and it works with
> his driver without any major issues.

Does the device reply to reads of the MT9M114_COMMAND_REGISTER register
but never shows the MT9M114_COMMAND_REGISTER_SET_STATE bit being set, or
does it not reply to reads at all (timeouts on the I2C bus) ?

> > >
> > >       if (sensor->bus_cfg.bus_type == V4L2_MBUS_PARALLEL) {
> > >               /*
> > > @@ -2207,9 +2215,11 @@ static int mt9m114_power_on(struct mt9m114 *sensor)
> > >        * reaches the standby mode (either initiated manually above in
> > >        * parallel mode, or automatically after reset in MIPI mode).
> > >        */
> > > -     ret = mt9m114_poll_state(sensor, MT9M114_SYS_STATE_STANDBY);
> > > -     if (ret < 0)
> > > -             goto error_clock;
> > > +     if (sensor->info->polling) {
> > > +             ret = mt9m114_poll_state(sensor, MT9M114_SYS_STATE_STANDBY);
> >
> > Ditto.
> >
> > > +             if (ret < 0)
> > > +                     goto error_clock;
> > > +     }
> > >
> > >       return 0;
> > >
> > > @@ -2421,6 +2431,8 @@ static int mt9m114_probe(struct i2c_client *client)
> > >       if (ret < 0)
> > >               return ret;
> > >
> > > +     sensor->info = of_device_get_match_data(dev);
> >
> > You can use device_get_match_data() here.
> 
> noted
> 
> > > +
> > >       /* Acquire clocks, GPIOs and regulators. */
> > >       sensor->clk = devm_v4l2_sensor_clk_get(dev, NULL);
> > >       if (IS_ERR(sensor->clk)) {
> > > @@ -2539,8 +2551,17 @@ static void mt9m114_remove(struct i2c_client *client)
> > >       pm_runtime_set_suspended(dev);
> > >  }
> > >
> > > +static const struct mt9m114_model_info mt9m114_models_default = {
> > > +     .polling = true,
> > > +};
> > > +
> > > +static const struct mt9m114_model_info mt9m114_models_aptina = {
> > > +     .polling = false,
> > > +};
> > > +
> > >  static const struct of_device_id mt9m114_of_ids[] = {
> > > -     { .compatible = "onnn,mt9m114" },
> > > +     { .compatible = "onnn,mt9m114", .data = &mt9m114_models_default },
> > > +     { .compatible = "aptina,mi1040", .data = &mt9m114_models_aptina },
> > >       { /* sentinel */ },
> >
> > The sentinel entry shouldn't have a comma. Feel free to fix that while at
> > it.
> 
> noted
> 
> > >  };
> > >  MODULE_DEVICE_TABLE(of, mt9m114_of_ids);

-- 
Regards,

Laurent Pinchart

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