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SD/eMMC: New Speed Modes and Their Support in Linux - Gregory Clement, Free Electrons

4,035 views · Published 24 October 2017 · 48:37 · Indexed 12 November 2026

Channel: The Linux Foundation · 2017 · Science & Technology

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SD/eMMC: New Speed Modes and Their Support in Linux - Gregory Clement, Free Electrons

Since the introduction of the original "default"(DS) and "high speed"(HS) modes, the SD card standard has evolved by introducing new speed modes, such as SDR12, SDR25, SDR50, SDR104, etc. The same happened to the eMMC standard, with the introduction of new high speed modes named DDR52, HS200, HS400, etc. The Linux kernel has obviously evolved to support these new speed modes, both in the MMC core and through the addition of new drivers.

This talk will start by introducing the SD and eMMC standards and how they work at the hardware level, with a specific focus on the new speed modes. With this hardware background in place, we will then detail how these standards are supported by Linux, see what is still missing, and what we can expect to see in the future.

About Gregory Clement
Gregory Clement is an embedded Linux engineer and trainer at Free Electrons since 2010. He has 17 years of on the field experience in porting and operating embedded Linux on many hardware architectures. He is currently involved in the integration of Marvell Armada SoCs (both ARM 32 and 64 bit versions) in the mainline Linux kernel, acting as co-maintainer for this mvebu ARM sub-architecture. As part of this port he recently worked on pushing in mainline an SD/eMMC controller supporting these ""new"" high speed modes.

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