Hi Daren, Guido, >From: Etheridge, Darren >>On 06/26/2014 10:40 AM, Guido Martínez wrote: >> I had some issues with this patch. Booting linux-next on a BeagleBone >> Black with this exact LCD left me with an unusable white screen. Please >> see below for some details. >> >>> On Tue, Jun 24, 2014 at 05:54:26PM +0530, Pekon Gupta wrote: >>> This patch adds support for LCD4 cape as advertised on >>> http://elinux.org/CircuitCo:BeagleBone_LCD4 >>> >>> This cape has: >>> * 480x272 TFT-LCD panel >>> - LCD panel datasheet and timing information are sourced from [1] >>> - LCD backlight is connected to 'EHRPWM1A' on cape board, but its used for >>> enabling backlight power-supply. So 'gpio-backlight' driver is used instead >>> of 'pwm-backlight' driver (Kconfig: BACKLIGHT_GPIO=y). >>> >>> * 4-wire resistive Touchscreen >>> >>> *Known constrains* >>> As LCD panel pins (lcd_data, hsync, vsync, pclk) are shared with on-board >>> NXP HDMI framer, so either HDMI or LCD-cape can be used at time. Thus while >>> using this cape 'hdmi' DT node needs to be disabled in am335x-boneblack.dts >>> >>> [1] www.newhavendisplay.com/specs/NHD-4.3-480272MF-ATXI-T-1.pdf >>> www.newhavendisplay.com/app_notes/OTA5180A.pdf >>> >>> Signed-off-by: Pekon Gupta <pekon@xxxxxx> >>> --- > ><snip> > >>> + >>> + panel { >>> + status = "disabled"; >>> + compatible = "ti,tilcdc,panel"; >>> + pinctrl-names = "default"; >>> + pinctrl-0 = <&bbcape_lcd_pins>; >>> + panel-info { >>> + ac-bias = <255>; >>> + ac-bias-intrpt = <0>; >>> + dma-burst-sz = <16>; >>> + bpp = <16>; >>> + fdd = <0x80>; >>> + sync-edge = <0>; >>> + sync-ctrl = <0>; >> I had to set this to <1>. Does that make sense? >> Yes, I'll check this one again at my end. >>> + raster-order = <0>; >>> + fifo-th = <0>; >>> + }; >>> + display-timings { >>> + native-mode = <&timing0>; >>> + /* www.newhavendisplay.com/app_notes/OTA5180A.pdf */ >>> + timing0: 480x272 { >>> + clock-frequency = <30000000>; >>> + hactive = <480>; >>> + vactive = <272>; >>> + hfront-porch = <8>; >>> + hback-porch = <47>; >>> + hsync-len = <41>; >>> + vback-porch = <2>; >>> + vfront-porch = <3>; >>> + vsync-len = <10>; >>> + hsync-active = <0>; >>> + vsync-active = <0>; >>> + de-active = <1>; >>> + pixelclk-active = <0>; >> Are you sure these timings are ok? When enabling the sync control I get >> an usable display, but it looks a bit funny. For example an all black >> display looks very clear and has a dotted pattern. >> >> I tried to take a picture of it but it doesn't show. >> I could run and test 'fbtest' and 'fbconsole' on this cape, using following configs CONFIG_DRM=y CONFIG_DRM_TILCDC=y [...] CONFIG_FB=y CONFIG_FIRMWARE_EDID=y CONFIG_FRAMEBUFFER_CONSOLE=y >These timings look wrong to me, for instance this sets a clock frequency >of 30MHz where as the linked app-note says 9MHz. I think the LCD4 cape >uses the same LCD panel as is used on the AM335x EVMSK. Therefore the >display timings from my DT patch for the EVMSK should work: >https://patchwork.kernel.org/patch/4144801/ > Yes, probably I got the pixel-clock timing wrong, I'll fix this. It should be 9.2MHz as per www.newhavendisplay.com/specs/NHD-4.3-480272MF-ATXI-T-1.pdf Table: Electrical Characteristics But as 'hsync' timings are relative to pixel-clock somehow it worked for me. I got other vsync and hsync timings from following reference: www.newhavendisplay.com/app_notes/OTA5180A.pdf Table: 8.4.1 480XRGBX272 Vertical Timing Table: 8.4.2 480XRGBX272 Horizontal Timing And I/O signal polarity for vsync-active and hsync-active from Table: 5. SIGNAL DESCRIPTIONS with regards, pekon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
