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([2a01:e0a:982:cbb0:302e:e0c2:d42c:cb23]) by smtp.gmail.com with ESMTPSA id g13-20020a056000118d00b003333d46a9e8sm7955435wrx.56.2023.12.11.00.29.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Dec 2023 00:29:11 -0800 (PST) Message-ID: <6f461d84-3c4c-4249-86a1-bc5149c97baf@linaro.org> Date: Mon, 11 Dec 2023 09:29:12 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: neil.armstrong@linaro.org Reply-To: neil.armstrong@linaro.org Subject: Re: [PATCH 1/3] drm/panel: st7701: Fix AVCL calculation Content-Language: en-US, fr To: Chris Morgan , devicetree@vger.kernel.org Cc: dri-devel@lists.freedesktop.org, linus.walleij@linaro.org, marex@denx.de, conor+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org, daniel@ffwll.ch, airlied@gmail.com, sam@ravnborg.org, quic_jesszhan@quicinc.com, jagan@amarulasolutions.com, Chris Morgan References: <20231208154847.130615-1-macroalpha82@gmail.com> <20231208154847.130615-2-macroalpha82@gmail.com> 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 Developer Services In-Reply-To: <20231208154847.130615-2-macroalpha82@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 08/12/2023 16:48, Chris Morgan wrote: > From: Chris Morgan > > The AVCL register, according to the datasheet, comes in increments > of -0.2v between -4.4v (represented by 0x0) to -5.0v (represented > by 0x3). The current calculation is done by adding the defined > AVCL value in mV to -4400 and then dividing by 200 to get the register > value. Unfortunately if I subtract -4400 from -4400 I get -8800, which > divided by 200 gives me -44. If I instead subtract -4400 from -4400 > I get 0, which divided by 200 gives me 0. Based on the datasheet this > is the expected register value. > > Fixes: 83b7a8e7e88e ("drm/panel/panel-sitronix-st7701: Parametrize voltage and timing") > > Signed-off-by: Chris Morgan > --- > drivers/gpu/drm/panel/panel-sitronix-st7701.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7701.c b/drivers/gpu/drm/panel/panel-sitronix-st7701.c > index 0459965e1b4f..036ac403ed21 100644 > --- a/drivers/gpu/drm/panel/panel-sitronix-st7701.c > +++ b/drivers/gpu/drm/panel/panel-sitronix-st7701.c > @@ -288,7 +288,7 @@ static void st7701_init_sequence(struct st7701 *st7701) > FIELD_PREP(DSI_CMD2_BK1_PWRCTRL2_AVDD_MASK, > DIV_ROUND_CLOSEST(desc->avdd_mv - 6200, 200)) | > FIELD_PREP(DSI_CMD2_BK1_PWRCTRL2_AVCL_MASK, > - DIV_ROUND_CLOSEST(-4400 + desc->avcl_mv, 200))); > + DIV_ROUND_CLOSEST(-4400 - desc->avcl_mv, 200))); > > /* T2D = 0.2us * T2D[3:0] */ > ST7701_DSI(st7701, DSI_CMD2_BK1_SPD1, Reviewed-by: Neil Armstrong