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([2a01:e0a:106d:1080:da6:dde3:e477:94d2]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4851ad02ffcsm11481675e9.20.2026.03.04.08.27.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Mar 2026 08:27:42 -0800 (PST) Message-ID: Date: Wed, 4 Mar 2026 17:27:41 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Neil Armstrong Reply-To: Neil Armstrong Subject: Re: [PATCH 4/4] drm/panel: himax-hx83102: Add support for DSI DCS backlight control To: Val Packett , Jessica Zhang , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: dri-devel@lists.freedesktop.org, phone-devel@vger.kernel.org, ~postmarketos/upstreaming@lists.sr.ht, linux-kernel@vger.kernel.org References: <20260217070121.190108-1-val@packett.cool> <20260217070121.190108-5-val@packett.cool> Content-Language: en-US, fr Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro In-Reply-To: <20260217070121.190108-5-val@packett.cool> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/17/26 08:00, Val Packett wrote: > The HTF065H045 panel based on the HX83102 controller does use DCS > commands for controlling backlight brightness. Make the driver fall back > to DCS when no external backlight has been defined in the device tree, > like many other drivers do. > > Signed-off-by: Val Packett > --- > drivers/gpu/drm/panel/panel-himax-hx83102.c | 65 +++++++++++++++++++++ > 1 file changed, 65 insertions(+) > > diff --git a/drivers/gpu/drm/panel/panel-himax-hx83102.c b/drivers/gpu/drm/panel/panel-himax-hx83102.c > index 34e0e956db48..8b2a68ee851e 100644 > --- a/drivers/gpu/drm/panel/panel-himax-hx83102.c > +++ b/drivers/gpu/drm/panel/panel-himax-hx83102.c > @@ -7,6 +7,7 @@ > * Based on drivers/gpu/drm/panel/panel-himax-hx8394.c > */ > > +#include > #include > #include > #include > @@ -76,6 +77,8 @@ struct hx83102_panel_desc { > unsigned int height_mm; > } size; > > + bool has_backlight; > + > int (*init)(struct hx83102 *ctx); > }; > > @@ -913,6 +916,7 @@ static const struct hx83102_panel_desc holitech_htf065h045_desc = { > .width_mm = 68, > .height_mm = 151, > }, > + .has_backlight = true, > .init = holitech_htf065h045_init, > }; > > @@ -1049,6 +1053,59 @@ static const struct drm_panel_funcs hx83102_drm_funcs = { > .get_orientation = hx83102_get_orientation, > }; > > +static int hx83102_bl_update_status(struct backlight_device *bl) > +{ > + struct mipi_dsi_device *dsi = bl_get_data(bl); > + u16 brightness = backlight_get_brightness(bl); > + int ret; > + > + dsi->mode_flags &= ~MIPI_DSI_MODE_LPM; > + > + ret = mipi_dsi_dcs_set_display_brightness_large(dsi, brightness); > + if (ret < 0) > + return ret; > + > + dsi->mode_flags |= MIPI_DSI_MODE_LPM; > + > + return 0; > +} > + > +static int hx83102_bl_get_brightness(struct backlight_device *bl) > +{ > + struct mipi_dsi_device *dsi = bl_get_data(bl); > + u16 brightness; > + int ret; > + > + dsi->mode_flags &= ~MIPI_DSI_MODE_LPM; > + > + ret = mipi_dsi_dcs_get_display_brightness_large(dsi, &brightness); > + if (ret < 0) > + return ret; > + > + dsi->mode_flags |= MIPI_DSI_MODE_LPM; > + > + return brightness; > +} > + > +static const struct backlight_ops hx83102_bl_ops = { > + .update_status = hx83102_bl_update_status, > + .get_brightness = hx83102_bl_get_brightness, > +}; > + > +static struct backlight_device * > +hx83102_create_dcs_backlight(struct mipi_dsi_device *dsi) > +{ > + struct device *dev = &dsi->dev; > + const struct backlight_properties props = { > + .type = BACKLIGHT_RAW, > + .brightness = 4095, > + .max_brightness = 4095, I guess those values could be in the hx83102_panel_desc. Anyway: Reviewed-by: Neil Armstrong Thanks, Neil > + }; > + > + return devm_backlight_device_register(dev, dev_name(dev), dev, dsi, > + &hx83102_bl_ops, &props); > +} > + > static int hx83102_panel_add(struct hx83102 *ctx) > { > struct device *dev = &ctx->dsi->dev; > @@ -1080,6 +1137,14 @@ static int hx83102_panel_add(struct hx83102 *ctx) > if (err) > return err; > > + /* Use DSI-based backlight as fallback if available */ > + if (ctx->desc->has_backlight && !ctx->base.backlight) { > + ctx->base.backlight = hx83102_create_dcs_backlight(ctx->dsi); > + if (IS_ERR(ctx->base.backlight)) > + return dev_err_probe(dev, PTR_ERR(ctx->base.backlight), > + "Failed to create backlight\n"); > + } > + > ctx->base.funcs = &hx83102_drm_funcs; > ctx->base.dev = &ctx->dsi->dev; >