Re: [PATCH v7 2/3] drm/bridge: ti-sn65dsi83: Add ti,lvds-vod-swing optional properties

Dmitry Baryshkov
2024-12-16T09:59:39Z

On Mon, Dec 16, 2024 at 09:54:09AM +0100, Andrej Picej wrote:
> Add a optional properties to change LVDS output voltage. This should not
> be static as this depends mainly on the connected display voltage
> requirement. We have three properties:
> - "ti,lvds-termination-ohms", which sets near end termination,
> - "ti,lvds-vod-swing-data-microvolt" and
> - "ti,lvds-vod-swing-clock-microvolt" which both set LVDS differential
> output voltage for data and clock lanes. They are defined as an array
> with min and max values. The appropriate bitfield will be set if
> selected constraints can be met.
>
> If "ti,lvds-termination-ohms" is not defined the default of 200 Ohm near
> end termination will be used. Selecting only one:
> "ti,lvds-vod-swing-data-microvolt" or
> "ti,lvds-vod-swing-clock-microvolt" can be done, but the output voltage
> constraint for only data/clock lanes will be met. Setting both is
> recommended.
>
> Signed-off-by: Andrej Picej <andrej.picej@norik.com>
> ---
> Changes in v7:
> - decrement refcount of the endpoint in all error cases,
> - add spaces to improve the readability of the long if statement conditions in
> sn65dsi83_select_lvds_vod_swing.
> Changes in v6:
> - rework termination resistor logic, default is now set by resistor value, not
> reg value,
> - move setting lvds_vod_swing_conf to default value of 0x1 inside if statement
> which checks if both properties are not set
> Changes in v5:
> - specify default values in sn65dsi83_parse_lvds_endpoint,
> - move sn65dsi83_parse_lvds_endpoint for channel B up, outside if,
> Changes in v4:
> - fix typo in commit message bitfiled -> bitfield
> - use arrays (lvds_vod_swing_conf and lvds_term_conf) in private data, instead
> of separate variables for channel A/B
> - add more checks on return value of "of_property_read_u32_array"
> Changes in v3:
> - use microvolts for default array values 1000 mV -> 1000000 uV.
> Changes in v2:
> - use datasheet tables to get the proper configuration
> - since major change was done change the authorship to myself
> ---
> drivers/gpu/drm/bridge/ti-sn65dsi83.c | 145 +++++++++++++++++++++++++-
> 1 file changed, 142 insertions(+), 3 deletions(-)
>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

--
With best wishes
Dmitry