Messages in this thread Patch in this message | | | From | Shreshtha Kumar SAHU <> | Date | Fri, 20 Apr 2012 12:24:56 +0200 | Subject | RE: [PATCH 1/2] leds-lm3530: comment correction about the range of brightness |
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IMHO it should be hidden inside driver. For example if hardware supports >8 bits for brightness then too we scale/map 0-255 to supported range in hardware.
BR Shreshtha
-----Original Message----- From: Kim, Milo [mailto:Milo.Kim@ti.com] Sent: Friday, April 20, 2012 2:14 PM To: Shreshtha Kumar SAHU Cc: linus.walleij@linaro.org; Richard Purdie; linux-kernel@vger.kernel.org; Andrew Morton Subject: RE: [PATCH 1/2] leds-lm3530: comment correction about the range of brightness
In the previous patch, max brightness was limited to 127 because only 7 bits are used in the brightness register.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=bbe6453204c568723679212f6d0653b92b3d6244
With this patch, 128 ~ 255 is invalid range of brightness, so comment needs to be corrected. (Even if the brt_val is greater than 127, the brightness will be set as max_brightness - 127)
Thanks & BR Milo -
> -----Original Message----- > From: Shreshtha Kumar SAHU [mailto:shreshthakumar.sahu@stericsson.com] > Sent: Friday, April 20, 2012 4:29 PM > To: Kim, Milo > Cc: linus.walleij@linaro.org; Richard Purdie; linux- > kernel@vger.kernel.org; Andrew Morton > Subject: RE: [PATCH 1/2] leds-lm3530: comment correction about the > range of brightness > > I feel driver should take care of range provided by hardware by > scaling the value provided by user, instead of limiting the max > brightness to user. > > For .e.g. here it can be something like this - > err = i2c_smbus_write_byte_data(drvdata->client, > LM3530_BRT_CTRL_REG, brt_val / 2); > > I am not sure if application really use/check max brightness in before > calculating/setting new brightness values. > > -----Original Message----- > From: Kim, Milo [mailto:Milo.Kim@ti.com] > Sent: Thursday, April 19, 2012 12:11 PM > To: Andrew Morton > Cc: Shreshtha Kumar SAHU; linus.walleij@linaro.org; Richard Purdie; > linux-kernel@vger.kernel.org > Subject: [PATCH 1/2] leds-lm3530: comment correction about the range of > brightness > > max brightness is 127, so the range of brt_val should be from 0 to 127 > > Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com> > --- > include/linux/led-lm3530.h | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/include/linux/led-lm3530.h b/include/linux/led-lm3530.h > index eeae6e7..4b13347 100644 > --- a/include/linux/led-lm3530.h > +++ b/include/linux/led-lm3530.h > @@ -92,7 +92,7 @@ struct lm3530_pwm_data { > * @als2_resistor_sel: internal resistance from ALS2 input to ground > * @als_vmin: als input voltage calibrated for max brightness in mV > * @als_vmax: als input voltage calibrated for min brightness in mV > - * @brt_val: brightness value (0-255) > + * @brt_val: brightness value (0-127) > * @pwm_data: PWM control functions (only valid when the mode is PWM) > */ > struct lm3530_platform_data { > -- > 1.7.4.1 > > > Best Regards, > Milo (Woogyom) Kim >
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