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([91.90.172.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-aa20e00172dsm194948266b.120.2024.11.15.08.07.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Nov 2024 08:07:53 -0800 (PST) From: Daniel Semkowicz To: Andrzej Hajda , Neil Armstrong , Robert Foss Cc: Daniel Semkowicz , 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 Subject: [PATCH 1/1] drm/bridge: tc358775: Remove burst mode support Date: Fri, 15 Nov 2024 17:06:32 +0100 Message-ID: <20241115160641.74074-2-dse@thaumatec.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241115160641.74074-1-dse@thaumatec.com> References: <20241115160641.74074-1-dse@thaumatec.com> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 Reviewed-by: Neil Armstrong --- 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