Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <47b70ca1-2601-0e71-80bd-6d3f3f845601@linaro.org>
Date:   Wed, 18 Jan 2023 10:45:30 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.6.0
From:   Neil Armstrong <neil.armstrong@linaro.org>
Reply-To: neil.armstrong@linaro.org
Subject: Re: [RFC PATCH v3 3/3] drm/panel: vtdr6130: Use 16-bit brightness
 function
Content-Language: en-US
To:     Richard Acayan <mailingradian@gmail.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Thierry Reding <thierry.reding@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Emil Velikov <emil.l.velikov@gmail.com>,
        Vinay Simha BN <simhavcs@gmail.com>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Cc:     Daniel Mentz <danielmentz@google.com>,
        Caleb Connolly <caleb@connolly.tech>
References: <20230116224909.23884-1-mailingradian@gmail.com>
 <20230116224909.23884-4-mailingradian@gmail.com>
Organization: Linaro Developer Services
In-Reply-To: <20230116224909.23884-4-mailingradian@gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 16/01/2023 23:49, Richard Acayan wrote:
> This panel communicates brightness in big endian. This is not a quirk of
> the panels themselves, but rather, a part of the MIPI standard. Use the
> new mipi_dsi_dcs_set_display_brightness_large() function that properly
> handles 16-bit brightness instead of bypassing the brightness functions
> entirely.
> 
> Signed-off-by: Richard Acayan <mailingradian@gmail.com>
> ---
>   drivers/gpu/drm/panel/panel-visionox-vtdr6130.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-visionox-vtdr6130.c b/drivers/gpu/drm/panel/panel-visionox-vtdr6130.c
> index f9a6abc1e121..1092075b31a5 100644
> --- a/drivers/gpu/drm/panel/panel-visionox-vtdr6130.c
> +++ b/drivers/gpu/drm/panel/panel-visionox-vtdr6130.c
> @@ -243,12 +243,9 @@ static int visionox_vtdr6130_bl_update_status(struct backlight_device *bl)
>   {
>   	struct mipi_dsi_device *dsi = bl_get_data(bl);
>   	u16 brightness = backlight_get_brightness(bl);
> -	/* Panel needs big-endian order of brightness value */
> -	u8 payload[2] = { brightness >> 8, brightness & 0xff };
>   	int ret;
>   
> -	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
> -				 payload, sizeof(payload));
> +	mipi_dsi_dcs_set_display_brightness_large(dsi, brightness);
>   	if (ret < 0)
>   		return ret;
>   

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-MTP

Thanks !