Hello, The e⋅MMC 5.0 specification has been published by JEDEC on September 2013 [1], and contains a note in section B.8, which says: "A host system should work properly considering future eMMC version. For example, a host system is expected not to exit only due to the EXT_CSD_REV[192] value greater than 7 which will be used for next e•MMC revision." Right now, the kernel controls the value of both fields 192 and 194, and rejects any device where CSD_STRUCTURE > 2 or EXT_CSD_REV > 7. During the updates to the specification, JEDEC has maintained forward compatibility, setting reserved bits in the EXT_CSD register to describe new mandatory and optional features. If the specification changes in an incompatible way, it is expected that the value in CSD_STRUCTURE will change. As a result, I believe it would not be an issue to remove the control on EXT_CSD_REV. I propose this change because e⋅MMC manufacturers are rapidly changing available references, and products with a long production life can encounter the situation where the kernel image, frozen at the beginning of the production, cannot support newer chips only because of this rule. [1] http://www.jedec.org/standards-documents/docs/jesd84-b50 (Free registration required) Best regards, -- Romain Izard -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
