https://bhuvanchandradv.github.io/tags/device-tree/ Recent content in Device-Tree on Bhuvan Chandra DV Hugo en Tue, 02 Feb 2016 11:55:43 +0800 https://bhuvanchandradv.github.io/blog/linux-lcd-timings/ Tue, 02 Feb 2016 11:55:43 +0800 https://bhuvanchandradv.github.io/blog/linux-lcd-timings/ <h3 id="mapping-lcdtft-display-timings-to-linux-kernel-data-structures">Mapping LCD/TFT display timings to Linux Kernel data structures</h3> <p>Most LCD/TFT display datasheets provide the following timing information:</p> <ul> <li><strong>Horizontal Back Porch (HBP)</strong>: Number of pixel clk pulses between HSYNC signal and the first valid pixel data.</li> <li><strong>Horizontal Front Porch (HFP)</strong>: Number of pixel clk pulses between the last valid pixel data in the line and the next hsync pulse.</li> <li><strong>Vertical Back Porch (VBP)</strong>: Number of lines (HSYNC pulses) from a VSYNC signal to the first valid line.</li> <li><strong>Vertical Front Porch (VFP)</strong>: Number of lines (HSYNC pulses) between the last valid line of the frame and the next VSYNC pulse.</li> <li><strong>VSYNC pulse width</strong>: Number of HSYNC pulses when a VSYNC signal is active.</li> <li><strong>HSYNC pulse width</strong>: Number of pixel clk pulses when a HSYNC signal is active.</li> <li><strong>Active frame width</strong>: Horizontal resolution.</li> <li><strong>Active frame height</strong>: Vertical resolution.</li> <li><strong>Screen width</strong>: <code>Active frame width + HBP + HFP</code></li> <li><strong>Screen height</strong>: <code>Active frame height + VBP + VFP</code></li> <li><strong>VSYNC polarity</strong>: Value of VSYNC to indicate the start of a new frame (active LOW or HIGH)</li> <li><strong>HSYNC polarity</strong>: Value of HSYNC to indicate the start of a new line (active LOW or HIGH)</li> </ul> <p>Some datasheets provide horizontal and vertical blanking period instead:</p>