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authorYijie Yang <yijie.yang@oss.qualcomm.com>2026-08-11 16:46:47 +0800
committerRob Herring (Arm) <robh@kernel.org>2026-08-15 15:46:52 -0500
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tree61c2297688373db165cc857b7c7adcb147a5c419 /Documentation/fb/arkfb.rst
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dt-bindings: interconnect: qcom-bwmon: Add Maili cpu-bwmon compatiblegrafted
Add the Qualcomm Maili SoC compatible string for the CPU bandwidth monitor (BWMONv4). This falls back to the sdm845-bwmon compatible, consistent with the existing pattern used by other recent SoCs such as sm8750 and kaanapali. Signed-off-by: Yijie Yang <yijie.yang@oss.qualcomm.com> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com> Reviewed-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com> Link: https://patch.msgid.link/20260811-bwmon-v2-1-80f7f150ab9e@oss.qualcomm.com Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
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+========================================
+arkfb - fbdev driver for ARK Logic chips
+========================================
+
+
+Supported Hardware
+==================
+
+ ARK 2000PV chip
+ ICS 5342 ramdac
+
+ - only BIOS initialized VGA devices supported
+ - probably not working on big endian
+
+
+Supported Features
+==================
+
+ * 4 bpp pseudocolor modes (with 18bit palette, two variants)
+ * 8 bpp pseudocolor mode (with 18bit palette)
+ * 16 bpp truecolor modes (RGB 555 and RGB 565)
+ * 24 bpp truecolor mode (RGB 888)
+ * 32 bpp truecolor mode (RGB 888)
+ * text mode (activated by bpp = 0)
+ * doublescan mode variant (not available in text mode)
+ * panning in both directions
+ * suspend/resume support
+
+Text mode is supported even in higher resolutions, but there is limitation to
+lower pixclocks (i got maximum about 70 MHz, it is dependent on specific
+hardware). This limitation is not enforced by driver. Text mode supports 8bit
+wide fonts only (hardware limitation) and 16bit tall fonts (driver
+limitation). Unfortunately character attributes (like color) in text mode are
+broken for unknown reason, so its usefulness is limited.
+
+There are two 4 bpp modes. First mode (selected if nonstd == 0) is mode with
+packed pixels, high nibble first. Second mode (selected if nonstd == 1) is mode
+with interleaved planes (1 byte interleave), MSB first. Both modes support
+8bit wide fonts only (driver limitation).
+
+Suspend/resume works on systems that initialize video card during resume and
+if device is active (for example used by fbcon).
+
+
+Missing Features
+================
+(alias TODO list)
+
+ * secondary (not initialized by BIOS) device support
+ * big endian support
+ * DPMS support
+ * MMIO support
+ * interlaced mode variant
+ * support for fontwidths != 8 in 4 bpp modes
+ * support for fontheight != 16 in text mode
+ * hardware cursor
+ * vsync synchronization
+ * feature connector support
+ * acceleration support (8514-like 2D)
+
+
+Known bugs
+==========
+
+ * character attributes (and cursor) in text mode are broken
+
+--
+Ondrej Zajicek <santiago@crfreenet.org>