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([2a01:e0a:982:cbb0:ed47:520d:3d5c:3acf]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-382398aa925sm6021314f8f.50.2024.11.18.00.43.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Nov 2024 00:43:56 -0800 (PST) Message-ID: <7ca35f75-3423-4ed3-bce0-6f3c7fa1f718@linaro.org> Date: Mon, 18 Nov 2024 09:43:56 +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@linaro.org Subject: Re: [PATCH 1/1] drm/bridge: tc358775: Remove burst mode support To: Daniel Semkowicz , Andrzej Hajda , Robert Foss Cc: David Airlie , Jernej Skrabec , Jonas Karlman , Laurent Pinchart , Maarten Lankhorst , Maxime Ripard , Michael Walle , Simona Vetter , Thomas Zimmermann , Tony Lindgren , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20241115160641.74074-1-dse@thaumatec.com> <20241115160641.74074-2-dse@thaumatec.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: <20241115160641.74074-2-dse@thaumatec.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 15/11/2024 17:06, Daniel Semkowicz wrote: > Current tc358775 bridge driver implementation assumes that DSI clock > is used as a source for LVDS pixel clock. Moreover, clock divider > PCLKDIV has a hard-coded value. This means that driver expects DSI > clock to always match a panel pixel clock. With such assumption, LVDS > pixel clock is configured to be (DSI pixel clock / 3) for single link. > This is true for DSI non-burst video modes. In burst mode, DSI host > is allowed to set transmission rate higher than pixel clock to allow > shorter data bursts. When the transmission rate is higher than expected > by the bridge, LVDS output timings are still configured for the lower > frequency, but the output is clocked with the higher one. In most cases, > bad LVDS timings cause incorrect panel operation. > > Remove support for burst mode, so the non-burst mode is used by DSI > host by default. Burst mode is supported by the bridge itself, > but requires proper implementation in the driver to operate correctly > in all scenarios. > > Fixes: a4ed72e85c46 ("drm/bridge: tc358775: Add burst and low-power modes") > Signed-off-by: Daniel Semkowicz > --- > > drivers/gpu/drm/bridge/tc358775.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/tc358775.c b/drivers/gpu/drm/bridge/tc358775.c > index 0b4efaca6d682..7496681c7b883 100644 > --- a/drivers/gpu/drm/bridge/tc358775.c > +++ b/drivers/gpu/drm/bridge/tc358775.c > @@ -632,8 +632,7 @@ static int tc_attach_host(struct tc_data *tc) > > dsi->lanes = tc->num_dsi_lanes; > dsi->format = MIPI_DSI_FMT_RGB888; > - dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | > - MIPI_DSI_MODE_LPM; > + dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_LPM; > > /* > * The hs_rate and lp_rate are data rate values. The HS mode is Reviewed-by: Neil Armstrong