Hi Sakari,
On Tuesday 17 May 2011 07:38:38 Sakari Ailus wrote:
> Laurent Pinchart wrote:
> > On Monday 16 May 2011 15:00:39 Sakari Ailus wrote:
> >> This patch adds the driver for the adp1653 LED flash controller. This
> >> controller supports a high power led in flash and torch modes and an
> >> indicator light, sometimes also called privacy light.
> >>
> >> The adp1653 is used on the Nokia N900.
> >>
> >> Signed-off-by: Sakari Ailus <sakari.ai...@maxwell.research.nokia.com>
> >> Signed-off-by: Tuukka Toivonen <tuukka...@gmail.com>
> >> Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> >> Signed-off-by: David Cohen <daco...@gmail.com>
> >
> > [snip]
> >
> >> diff --git a/drivers/media/video/adp1653.c
> >> b/drivers/media/video/adp1653.c new file mode 100644
> >> index 0000000..92ea38b
> >> --- /dev/null
> >> +++ b/drivers/media/video/adp1653.c
> >
> > [snip]
> >
> >> +/* Write values into ADP1653 registers. */
> >> +static int adp1653_update_hw(struct adp1653_flash *flash)
> >> +{
> >> + struct i2c_client *client = v4l2_get_subdevdata(&flash->subdev);
> >> + u8 out_sel;
> >> + u8 config = 0;
> >> + int rval;
> >> +
> >> + out_sel = flash->indicator_intensity->val
> >> + << ADP1653_REG_OUT_SEL_ILED_SHIFT;
> >> +
> >> + switch (flash->led_mode->val) {
> >> + case V4L2_FLASH_LED_MODE_NONE:
> >> + break;
> >> + case V4L2_FLASH_LED_MODE_FLASH:
> >> + /* Flash mode, light on with strobe, duration from timer */
> >> + config = ADP1653_REG_CONFIG_TMR_CFG;
> >> + config |= TIMEOUT_US_TO_CODE(flash->flash_timeout->val)
> >> + << ADP1653_REG_CONFIG_TMR_SET_SHIFT;
> >> + break;
> >> + case V4L2_FLASH_LED_MODE_TORCH:
> >> + /* Torch mode, light immediately on, duration indefinite */
> >> + out_sel |= flash->torch_intensity->val
> >> + << ADP1653_REG_OUT_SEL_HPLED_SHIFT;
> >> + break;
> >> + }
> >> +
> >> + rval = i2c_smbus_write_byte_data(client, ADP1653_REG_OUT_SEL,
> >> out_sel);
> >
> > out_sel can be used uninitialized here.
>
> I don't think so. It's assigned a value in the beginning of the function.
My bad, I missed that. Sorry.
> >> + if (rval < 0)
> >> + return rval;
> >> +
> >> + rval = i2c_smbus_write_byte_data(client, ADP1653_REG_CONFIG, config);
> >> + if (rval < 0)
> >> + return rval;
> >> +
> >> + return 0;
> >> +}
> >
> > [snip]
> >
> >> +static int adp1653_get_ctrl(struct v4l2_ctrl *ctrl)
> >> +{
> >> + struct adp1653_flash *flash =
> >> + container_of(ctrl->handler, struct adp1653_flash, ctrls);
> >> + struct i2c_client *client = v4l2_get_subdevdata(&flash->subdev);
> >> + int fault;
> >> + int rval;
> >> +
> >> + fault = i2c_smbus_read_byte_data(client, ADP1653_REG_FAULT);
> >> + if (IS_ERR_VALUE(fault))
> >> + return fault;
> >> +
> >> + /* Clear faults. */
> >> + rval = i2c_smbus_write_byte_data(client, ADP1653_REG_OUT_SEL, 0);
> >> + if (IS_ERR_VALUE(rval))
> >> + return rval;
> >
> > If several applications read controls, only one of them will be notified
> > of faults. Shouldn't clearing the fault be handled explicitly by writing
> > to a control ? I know this changes the API :-)
>
> This is true.
>
> Although I can't imagine right now why two separate processes should be
> so interested in the faults but it is still entirely possible that
> someone does that since it's permitted by the interface.
>
> Having to write zero to faults to clear them isn't good either since it
> might mean missing faults that are triggered between reading and writing
> this control.
>
> Perhaps this would make sense as a file handle specific control?
Good question. Control events will help I guess, maybe that's the solution.
> The control documentation says that the faults are cleared when the
> register is read, but the adp1653 also clears the faults whenever
> writing zero to out_sel which happens also in other circumstances, for
> example when changing mode from flash to torch when the torch intensity
> is zero, or when indicator intensity is zero in other modes.
>
> >> + /* Restore configuration. */
> >> + rval = adp1653_update_hw(flash);
> >> + if (IS_ERR_VALUE(rval))
> >> + return rval;
> >
> > Will that produce expected results ? For instance, if a fault was
> > detected during flash strobe, won't it try to re-strobe the flash ?
> > Shouldn't the user
>
> No. Flash is strobed using adp1653_strobe().
>
> > be required to explicitly re-strobe the flash or turn the torch (or
> > indicator) on after a fault ? Once again this should be clarified in the
> > API :-)
>
> The mode won't be changed from the flash but to strobe again, the user
> has to push V4L2_CID_FLASH_STROBE again.
>
> The adp1653 doesn't have any torch (as such) or indicator faults; some
> other chips do have indicator faults at least. Using the torch mode
> might trigger faults, too, since it's the same LED; just the power isn't
> that high.
When an over-current fault is detected, shouldn't the mode be set back to none
? If we just clear the fault and reprogram the registers, the torch will be
turned back on, and the fault will likely happen again.
--
Regards,
Laurent Pinchart
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