Hi Chris,

Thank you for the patch.

On Fri, Sep 02, 2022 at 10:39:06AM -0500, Chris Morgan wrote:
> From: Chris Morgan <macromor...@hotmail.com>
> 
> Add the option to set the byteswap order in the devicetree. For the
> official HDMI DIP for the NTC CHIP the byteswap order needs to be
> RGB, however the driver sets it as BGR. With this patch the driver
> will remain at BGR unless manually specified via devicetree.
> 
> Signed-off-by: Chris Morgan <macromor...@hotmail.com>
> Reviewed-by: Robert Foss <robert.f...@linaro.org>
> ---
>  drivers/gpu/drm/bridge/chrontel-ch7033.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/chrontel-ch7033.c 
> b/drivers/gpu/drm/bridge/chrontel-ch7033.c
> index ba060277c3fd..c5719908ce2d 100644
> --- a/drivers/gpu/drm/bridge/chrontel-ch7033.c
> +++ b/drivers/gpu/drm/bridge/chrontel-ch7033.c
> @@ -68,6 +68,7 @@ enum {
>       BYTE_SWAP_GBR   = 3,
>       BYTE_SWAP_BRG   = 4,
>       BYTE_SWAP_BGR   = 5,
> +     BYTE_SWAP_MAX   = 6,
>  };
>  
>  /* Page 0, Register 0x19 */
> @@ -355,6 +356,8 @@ static void ch7033_bridge_mode_set(struct drm_bridge 
> *bridge,
>       int hsynclen = mode->hsync_end - mode->hsync_start;
>       int vbporch = mode->vsync_start - mode->vdisplay;
>       int vsynclen = mode->vsync_end - mode->vsync_start;
> +     u8 byte_swap;
> +     int ret;
>  
>       /*
>        * Page 4
> @@ -398,8 +401,16 @@ static void ch7033_bridge_mode_set(struct drm_bridge 
> *bridge,
>       regmap_write(priv->regmap, 0x15, vbporch);
>       regmap_write(priv->regmap, 0x16, vsynclen);
>  
> -     /* Input color swap. */
> -     regmap_update_bits(priv->regmap, 0x18, SWAP, BYTE_SWAP_BGR);
> +     /* Input color swap. Byte order is optional and will default to
> +      * BYTE_SWAP_BGR to preserve backwards compatibility with existing
> +      * driver.
> +      */
> +     ret = of_property_read_u8(priv->bridge.of_node, "chrontel,byteswap",
> +                               &byte_swap);

That's quite inefficient, please parse the device tree at probe time,
and cache the value.

> +     if (!ret && byte_swap < BYTE_SWAP_MAX)
> +             regmap_update_bits(priv->regmap, 0x18, SWAP, byte_swap);
> +     else
> +             regmap_update_bits(priv->regmap, 0x18, SWAP, BYTE_SWAP_BGR);
>  
>       /* Input clock and sync polarity. */
>       regmap_update_bits(priv->regmap, 0x19, 0x1, mode->clock >> 16);

-- 
Regards,

Laurent Pinchart

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