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([2a01:e0a:3d9:2080:3ae8:20b:c783:9328]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-458705376d2sm187799235e9.3.2025.07.29.02.17.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Jul 2025 02:17:11 -0700 (PDT) Message-ID: <8cbbf5f8-84b4-43af-89b9-0ee4bc0a2591@linaro.org> Date: Tue, 29 Jul 2025 11:17:10 +0200 Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: neil.armstrong@linaro.org Reply-To: Neil Armstrong Subject: Re: [PATCH v2 1/3] drm/panel: novatek-nt35560: Fix invalid return value To: Brigham Campbell , maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, linus.walleij@linaro.org, jessica.zhang@oss.qualcomm.com, sam@ravnborg.org Cc: dianders@chromium.org, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20250729054435.1209156-1-me@brighamcampbell.com> <20250729054435.1209156-2-me@brighamcampbell.com> 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: <20250729054435.1209156-2-me@brighamcampbell.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29/07/2025 07:44, Brigham Campbell wrote: > Fix bug in nt35560_set_brightness() which causes the function to > erroneously report an error. mipi_dsi_dcs_write() returns either a > negative value when an error occurred or a positive number of bytes > written when no error occurred. The buggy code reports an error under > either condition. > > Fixes: 7835ed6a9e86 ("drm/panel-sony-acx424akp: Modernize backlight handling") > Signed-off-by: Brigham Campbell > --- > drivers/gpu/drm/panel/panel-novatek-nt35560.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35560.c b/drivers/gpu/drm/panel/panel-novatek-nt35560.c > index 98f0782c8411..17898a29efe8 100644 > --- a/drivers/gpu/drm/panel/panel-novatek-nt35560.c > +++ b/drivers/gpu/drm/panel/panel-novatek-nt35560.c > @@ -161,7 +161,7 @@ static int nt35560_set_brightness(struct backlight_device *bl) > par = 0x00; > ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY, > &par, 1); > - if (ret) { > + if (ret < 0) { > dev_err(nt->dev, "failed to disable display backlight (%d)\n", ret); > return ret; > } Reviewed-by: Neil Armstrong