[PATCH v3 1/2] drm/dsi: Implement dcs set/get display brightness

[Vinay Simha]

just to be inline with the existing code (funcs:
mipi_dsi_dcs_get_power_mode, mipi_dsi_dcs_get_pixel_format) in
drivers/gpu/drm/drm_mipi_dsi.c followed the same for
mipi_dsi_dcs_get_display_brightness

We may need to change as you suggested for other two functions also.
please suggest.




On Tue, Jul 19, 2016 at 3:00 PM, Sean Paul <seanpaul at google.com> wrote:
> On Mon, Jul 18, 2016 at 4:28 AM, Vinay Simha BN <simhavcs at gmail.com> wrote:
>> Provide a small convenience wrapper that set/get the
>> display brightness value
>>
>> Cc: John Stultz <john.stultz at linaro.org>
>> Cc: Sumit Semwal <sumit.semwal at linaro.org>
>> Cc: Archit Taneja <archit.taneja at gmail.com>
>> Cc: Rob Clark <robdclark at gmail.com>
>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> Cc: Thierry Reding <thierry.reding at gmail.com>
>> Cc: Emil Velikov <emil.l.velikov at gmail.com>
>> Signed-off-by: Vinay Simha BN <simhavcs at gmail.com>
>>
>> ---
>> v1:
>>  *tested in nexus7 2nd gen.
>>
>> v2:
>>  * implemented jani review comments
>>    -functions name mapped accordingly
>>    -bl value increased from 0xff to 0xffff
>>    -backlight interface will be handled in panel driver,
>>     so it is moved from the mipi_dsi helper function
>>
>> v3:
>>  * emil review comments
>>    (err < 0) supposed to be (err <= 0)
>> ---
>>  drivers/gpu/drm/drm_mipi_dsi.c | 49 ++++++++++++++++++++++++++++++++++++++++++
>>  include/drm/drm_mipi_dsi.h     |  4 ++++
>>  2 files changed, 53 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
>> index af0d471..43aa743 100644
>> --- a/drivers/gpu/drm/drm_mipi_dsi.c
>> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
>> @@ -1041,6 +1041,55 @@ int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format)
>>  }
>>  EXPORT_SYMBOL(mipi_dsi_dcs_set_pixel_format);
>>
>> +/**
>> + * mipi_dsi_dcs_get_display_brightness() - gets the current brightness value
>> + * of the display
>> + * @dsi: DSI peripheral device
>> + * @brightness: brightness value
>> + *
>> + * Return: 0 on success or a negative error code on failure.
>> + */
>> +int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
>> +                                       u16 *brightness)
>> +{
>> +       ssize_t err;
>> +
>> +       err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
>> +                               brightness, sizeof(*brightness));
>> +       if (err <= 0) {
>> +               if (err == 0)
>> +                       err = -ENODATA;
>> +
>> +               return err;
>> +       }
>> +
>> +       return 0;
>
> IMO, this is still pretty awkward. I think the following is a bit more
> conventional:
>
> err = mipi_dsi_dcs_...
> if (err == 0)
>     return -ENODATA;
> else if (err < 0)
>     return err;
>
> return 0;
>
>> +}
>> +EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness);
>> +
>> +/**
>> + * mipi_dsi_dcs_set_display_brightness() - sets the brightness value of
>> + * the display
>> + * @dsi: DSI peripheral device
>> + * @brightness: brightness value
>> + *
>> + * Return: 0 on success or a negative error code on failure.
>> + */
>> +int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
>> +                                       u16 brightness)
>> +{
>> +       ssize_t err;
>> +       u8 bl_value[2] = { brightness & 0xff, brightness >> 8 };
>> +
>> +       err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
>> +                                bl_value, sizeof(bl_value));
>> +       if (err < 0)
>> +               return err;
>> +
>> +       return 0;
>> +}
>> +EXPORT_SYMBOL(mipi_dsi_dcs_set_display_brightness);
>> +
>>  static int mipi_dsi_drv_probe(struct device *dev)
>>  {
>>         struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);
>> diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
>> index 47ac925..404c373 100644
>> --- a/include/drm/drm_mipi_dsi.h
>> +++ b/include/drm/drm_mipi_dsi.h
>> @@ -270,6 +270,10 @@ int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
>>  int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
>>                              enum mipi_dsi_dcs_tear_mode mode);
>>  int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format);
>> +int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
>> +                                       u16 *brightness);
>> +int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
>> +                                       u16 brightness);
>>
>>  /**
>>   * struct mipi_dsi_driver - DSI driver
>> --
>> 2.1.2
>>



-- 
Regards,

Vinay Simha.B.N.